Re: [time-nuts] GPS Spoofing
Have you done any DF work with low chip rate spread spectrum signals down in the noise.It's not easy and you need to fft for the data A high power pulse train lots easier to DF Sent from my iPhone On Jul 27, 2013, at 3:44 PM, Bob Camp li...@rtty.us wrote: Hi A Loran jammer would / could work with a *much* smaller antenna if a local area was the target. Power is easy at 100 KHz. Loran is no easier / harder to DF than GPS. Bob On Jul 27, 2013, at 3:37 PM, Scott McGrath scmcgr...@gmail.com wrote: LORAN was/is not perfect geographic features could and did limit reception However an effective jammer would need effective power in the hundred watt range and a efficient antenna system plus a connection to power grid or small Genset. Not amenable to easy concealment and fairly easy to DF using standard techniques especially since location of real station well known and fixed An effective GPS jammer which can take out a few square miles is the size of a trade paperback and runs on batteries and costs under 50 bucks to build Imagine a scenario where a few hundred of these are deployed with hostile intent. Military and Civillian systems are now useless due to nature of signal they are hard to DF Sent from my iPhone On Jul 27, 2013, at 2:09 PM, Bob Camp li...@rtty.us wrote: Hi Loran can / could easily be jammed over a limited area, just like GPS. Nothing crazy large or expensive would be required. The same sort of malfunctioning this or that took out Loran from time to time over harbor sized areas. Loran had so many issues with dropping out, that they simply were not worth talking about …. Bob On Jul 27, 2013, at 1:35 PM, Scott McGrath scmcgr...@gmail.com wrote: Key Problem with GPS is its easy to spoof on one level and have a complete denial of service on the other. Out in California a while back a malfunctioning TV distribution amplifier jammed a major harbor and surrounding almost 25 sq miles affected all because of a 49.95 TV amp had a problem. The military receivers had the same problem LORAN is virtually jam proof unless you have a very powerful transmitter Sent from my iPhone On Jul 27, 2013, at 11:17 AM, Michael Perrett mkperr...@gmail.com wrote: I have seen a lot of differing opinions on GPS Spoofing and using back up systems on this thread. Most pretty good, but a couple off the mark a bit. Here are a couple of comments on GPS Spoofing. - There are anti-spoofing GPS receivers available - to authorized users. Typically DOD. Most, if not all, military receivers utilize the encrypted P-Code, while civilians must use the more vulnerable clear text C/A code. The P-Code signals are very difficult to spoof unless you have a-pirori knowledge. The newer satellites (GPS III) will have an even more robust AS methodology. - Note: beware of P-Code, or Military, receivers available on eBay. They are useless without the encryption keys distributed by the US Government. - In the (near?) future there will be four civilian GPS Signals: The government is in the process of fielding three new signals designed for civilian use: L2C, L5, and L1C. The legacy civil signal, called L1 C/A or C/A at L1, will continue broadcasting in the future, for a total of four civil GPS signals. Users must upgrade their equipment to benefit from the new signals. ref http://www.gps.gov/systems/gps/modernization/civilsignals/ - Receivers utilizing the new civilian GPS frequencies can solve the GPS equations from more than one frequency and see if any one signal is being spoofed. The new civilian frequencies will be more spoof resistant. Comments on using inertial measurement units (IMUs) to back up GPS. - Current IMUs with even a good drift rate of say, 1 degree per hour, available for around a few thousand dollars, will be off 60 nautical miles after an hour of uncorrected operation. That can be reduced by other sensor inputs (GPS, LORAN, pit-log or what ever you have), but the navigation solution will eventually degrade to the accuracy of the external sensor. If my memory serves me for a really deep pocket navigator (having tens to hundreds of thousands of dollars, and a large amount of available mounting space) IMUs with drift rates of up to a thousand times less can be purchased (that's ,001 miles per hour, or around a couple of meters per hour), think submarines, etc. Using a dual sensor navigation system (or timing system! ), such as GPS/eLORAN, would obviously make the system so much more robust. Michael / K7HIL On Sat, Jul 27, 2013 at 6:43 AM, Scott McGrath scmcgr...@gmail.com wrote: Key here is how does the captain know that GPS is no longer providing an accurate fix? You need 2 or more independent systems to cross check each other. Sent from my iPhone On Jul 27, 2013, at 12:21 AM, Jim Lux jim...@earthlink.net wrote: On 7/26/13 8:45 PM, J. Forster
Re: [time-nuts] GPS Spoofing
LF is much easier to accurately DF than VHF and above due to multipath effects. Stewart Sent from my iPad On 27 Jul 2013, at 21:44, Bob Camp li...@rtty.us wrote: Hi A Loran jammer would / could work with a *much* smaller antenna if a local area was the target. Power is easy at 100 KHz. Loran is no easier / harder to DF than GPS. Bob On Jul 27, 2013, at 3:37 PM, Scott McGrath scmcgr...@gmail.com wrote: LORAN was/is not perfect geographic features could and did limit reception However an effective jammer would need effective power in the hundred watt range and a efficient antenna system plus a connection to power grid or small Genset. Not amenable to easy concealment and fairly easy to DF using standard techniques especially since location of real station well known and fixed An effective GPS jammer which can take out a few square miles is the size of a trade paperback and runs on batteries and costs under 50 bucks to build Imagine a scenario where a few hundred of these are deployed with hostile intent. Military and Civillian systems are now useless due to nature of signal they are hard to DF Sent from my iPhone On Jul 27, 2013, at 2:09 PM, Bob Camp li...@rtty.us wrote: Hi Loran can / could easily be jammed over a limited area, just like GPS. Nothing crazy large or expensive would be required. The same sort of malfunctioning this or that took out Loran from time to time over harbor sized areas. Loran had so many issues with dropping out, that they simply were not worth talking about …. Bob On Jul 27, 2013, at 1:35 PM, Scott McGrath scmcgr...@gmail.com wrote: Key Problem with GPS is its easy to spoof on one level and have a complete denial of service on the other. Out in California a while back a malfunctioning TV distribution amplifier jammed a major harbor and surrounding almost 25 sq miles affected all because of a 49.95 TV amp had a problem. The military receivers had the same problem LORAN is virtually jam proof unless you have a very powerful transmitter Sent from my iPhone On Jul 27, 2013, at 11:17 AM, Michael Perrett mkperr...@gmail.com wrote: I have seen a lot of differing opinions on GPS Spoofing and using back up systems on this thread. Most pretty good, but a couple off the mark a bit. Here are a couple of comments on GPS Spoofing. - There are anti-spoofing GPS receivers available - to authorized users. Typically DOD. Most, if not all, military receivers utilize the encrypted P-Code, while civilians must use the more vulnerable clear text C/A code. The P-Code signals are very difficult to spoof unless you have a-pirori knowledge. The newer satellites (GPS III) will have an even more robust AS methodology. - Note: beware of P-Code, or Military, receivers available on eBay. They are useless without the encryption keys distributed by the US Government. - In the (near?) future there will be four civilian GPS Signals: The government is in the process of fielding three new signals designed for civilian use: L2C, L5, and L1C. The legacy civil signal, called L1 C/A or C/A at L1, will continue broadcasting in the future, for a total of four civil GPS signals. Users must upgrade their equipment to benefit from the new signals. ref http://www.gps.gov/systems/gps/modernization/civilsignals/ - Receivers utilizing the new civilian GPS frequencies can solve the GPS equations from more than one frequency and see if any one signal is being spoofed. The new civilian frequencies will be more spoof resistant. Comments on using inertial measurement units (IMUs) to back up GPS. - Current IMUs with even a good drift rate of say, 1 degree per hour, available for around a few thousand dollars, will be off 60 nautical miles after an hour of uncorrected operation. That can be reduced by other sensor inputs (GPS, LORAN, pit-log or what ever you have), but the navigation solution will eventually degrade to the accuracy of the external sensor. If my memory serves me for a really deep pocket navigator (having tens to hundreds of thousands of dollars, and a large amount of available mounting space) IMUs with drift rates of up to a thousand times less can be purchased (that's ,001 miles per hour, or around a couple of meters per hour), think submarines, etc. Using a dual sensor navigation system (or timing system! ), such as GPS/eLORAN, would obviously make the system so much more robust. Michael / K7HIL On Sat, Jul 27, 2013 at 6:43 AM, Scott McGrath scmcgr...@gmail.com wrote: Key here is how does the captain know that GPS is no longer providing an accurate fix? You need 2 or more independent systems to cross check each other. Sent from my iPhone On Jul 27, 2013, at 12:21 AM, Jim Lux jim...@earthlink.net wrote: On 7/26/13 8:45 PM, J. Forster wrote: I gather from the article, the GPS position was spoofed and the autopilot, in bringing it
Re: [time-nuts] GPS locked 60Hz?
My mate worked in telecom in the 70's where the backup diesel generators used exactly the same method. Due to a fluke a spike or something blew all 3 globes (Australia is 3 phase). My mate assumed the generator was synced up and closed the breaker. When he picked himself up from the other side of the room the breaker had exploded and the driveshaft of the diesel (to use his words) was twisted up like a dishcloth. He took a long time to live this down. On 28 July 2013 09:46, Chris Albertson albertson.ch...@gmail.com wrote: The old time (stone age) method of setting the phase of a power generator was easy: Get an ordinary light bulb and connect it between the grid and your generator, Adjust the phase of your generator until the bulb goes dim. When the bulb is 100% dead out then flip the switch and connect the load. They had it a lot easier before there were computers and good instruments. On Sat, Jul 27, 2013 at 2:52 PM, Bob Camp li...@rtty.us wrote: Hi The guys who put up the original papers were from Quebec Hydro. Their issue was trying to set things up independent of the grid and dispatch power to where ever it was needed. Once they demonstrated it was possible a lot of other people became interested. Oddly enough at dinner I brought up the possibility of using Loran-C to them. Their commit was have you ever tried to get 100 KHz past the field of a hydro station --- no way!!!. Actually the last part of it was in French, but that's as close as I an get …. Bob On Jul 27, 2013, at 4:10 PM, Bob Stewart b...@evoria.net wrote: But wouldn't it be easier to set phase if they had a known, good frequency? Oh. Frequency isn't the issue, is it? If you have to supply to the west coast for a few hours and then plug into the east coast to purchase power, you might have to do a large phase shift between the two. And after some arbitrary timeframe doing still more bouncing around you could be off in frequency as measured locally in the long term. This idea just hit me because the Tymeter uses a synchronous clock drive. And giving it some thought, I guess it's not that big a deal if you start with a cheap UPS and a good clock. Bob From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, July 27, 2013 2:42 PM Subject: Re: [time-nuts] GPS locked 60Hz? Hi If you go back into the Frequency Control Symposium papers from the 1980's there are several of them from the power line people on using GPS to track 60 Hz. They have kept at it ever since. Their main interest is in tracking phase across a large network, rather than locking up generators (for accurate time). Knowing phase lets them better balance power flow(s) and thus save money. Bob On Jul 27, 2013, at 3:11 PM, Tim Shoppa tsho...@gmail.com wrote: http://leapsecond.com/pages/atomic-nixie/ shows a KVARZ CH1-75 Active Hydrogen Maser (5 MHz) through a HP 3325B synthesizer (60 Hz) through a HP 6827A bipolar power supply (100 VAC) to generate a 60 Hz mains. At http://leapsecond.com/pages/mains/ he also shows the 60Hz grid meandering forward and back plus or minus 5 or 10 seconds over a month in 2004. On Sat, Jul 27, 2013 at 1:54 PM, Bob Stewart b...@evoria.net wrote: My Tymeter just clacked over to 50 minutes after, and I had a sudden vision of GPS locking its input to 60 Hz, like in the good old days when the power companies cared about frequency. =) Has anyone actually gone that far in their time-madness? Bob - AE6RV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To
Re: [time-nuts] Rockwell/Conexant Jupiter(?) 10kHz Output Off Frequency
Hi David Aside from in the Jupiter itself the Zodiac chipset was widely used in GPS navigational receivers and, just for example there's one that's possibly similar to yours, albeit marked ZOD1, shown here http://www.gpsnuts.com/mygps/gps/hardware%20reviews/randmcnally/rand_mcnally _gps.htm I assume you're aware that although the 1PPS and 10KHz were themselves locked together in most, and possibly all, versions of the Jupiter, in the earlier versions, at least up until firmware 1.03, these weren't in sync with UTC. Later versions, 1.50 for example, were in sync but other settling down issues have resulted in version 1.80 being generally accepted as the earlist fully stable release. However, in this instance I suspect what you've got is far enough removed from a Jupiter that the firmware is different and that 1.83 firmware version number is probably just an unfortunate coincidence. What you're seeing exactly describes the situation in the earlier Jupiters so it would seem likely that 1 PPS and 10KHz just aren't synchronised to UTC in these either. Regards Nigel GM8PZR In a message dated 28/07/2013 00:23:42 GMT Daylight Time, da...@smithfamily.net.au writes: The Jupiter (TU-30) board in my homebrew GPSDO has died. A friend gave me some unmarked Jupiter-like boards with Conexant chips that he had been told were Jupiter compatible. The boards are mounted on an aluminium plate that has a puck-type antenna on it. One of the chips has a sticker with ZOD8 V1.83 printed on it. The boards have the same connections as a Jupiter, and I've been able to connect one to my GPSDO in place of the dead Jupiter. It eventually starts outputting sensible messages with location etc. and the homemade display on the GPSDO shows that everything is supposedly normal. However, the PLL will not lock. Even though there's 10 kHz from the board (which I can only measure to 1 Hz accuracy), the PLL keeps hunting for lock. The 10kHz is in sync with the 1pps also from the board. However, when I compare the 10kHz to 10 MHz from another GPSDO, it doesn't appear synced to GPS - it must only be fractions of a Hz off, though. At the moment, I'm thinking there are 3 possibilities: - I need to send a command to the board to configure the 10kHz/1pps somehow. The Jupiter doco doesn't show any command like that and seems to assume the 10kHz and 1pps are always there. - There are components for the 10kHz/1pps syncing missing. I've already had to add a jumper wire where bits for supplying active antenna power were missing (from factory). - The firmware doesn't support 1pps / 10kHz. Perhaps the boards were meant for navigation only. Does anyone recognise these boards and have experience with extracting 10kHz from them? Regards, David Smith ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] More pictures of the mystery Collins Ru
Well, the outside label does claim it was made by GENRAD... ;-) 73, geo - n4ua On Sat, Jul 27, 2013 at 9:24 PM, Pete Lancashire p...@petelancashire.comwrote: https://plus.google.com/u/0/photos/111617808980322733757/albums/5890266601277045697 The board with the edge connector was inside the same bag the connector was in, the bag was taped to the unit. I pulled the ends off first, but was immediately stopped with foam, it is glued in place. Then when I finally got the lid with all the screws off, all there is, is one board covered in potting compound. The compound breaks away pretty easily. One can see where a couple parts were replaced and there soft RTV was used. There are two precision resistors in that area. The biggest surprise is the General Radio logo on the board ! goo.gl/1XGG2F ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
Hi One could say VHF is much easier to DF than LF due to the small antennas needed. Short wavelength makes the antenna for a phase based receiver easier to build. Bob On Jul 28, 2013, at 5:03 AM, stew...@g3ysx.org.uk stew...@g3ysx.org.uk wrote: LF is much easier to accurately DF than VHF and above due to multipath effects. Stewart Sent from my iPad On 27 Jul 2013, at 21:44, Bob Camp li...@rtty.us wrote: Hi A Loran jammer would / could work with a *much* smaller antenna if a local area was the target. Power is easy at 100 KHz. Loran is no easier / harder to DF than GPS. Bob On Jul 27, 2013, at 3:37 PM, Scott McGrath scmcgr...@gmail.com wrote: LORAN was/is not perfect geographic features could and did limit reception However an effective jammer would need effective power in the hundred watt range and a efficient antenna system plus a connection to power grid or small Genset. Not amenable to easy concealment and fairly easy to DF using standard techniques especially since location of real station well known and fixed An effective GPS jammer which can take out a few square miles is the size of a trade paperback and runs on batteries and costs under 50 bucks to build Imagine a scenario where a few hundred of these are deployed with hostile intent. Military and Civillian systems are now useless due to nature of signal they are hard to DF Sent from my iPhone On Jul 27, 2013, at 2:09 PM, Bob Camp li...@rtty.us wrote: Hi Loran can / could easily be jammed over a limited area, just like GPS. Nothing crazy large or expensive would be required. The same sort of malfunctioning this or that took out Loran from time to time over harbor sized areas. Loran had so many issues with dropping out, that they simply were not worth talking about …. Bob On Jul 27, 2013, at 1:35 PM, Scott McGrath scmcgr...@gmail.com wrote: Key Problem with GPS is its easy to spoof on one level and have a complete denial of service on the other. Out in California a while back a malfunctioning TV distribution amplifier jammed a major harbor and surrounding almost 25 sq miles affected all because of a 49.95 TV amp had a problem. The military receivers had the same problem LORAN is virtually jam proof unless you have a very powerful transmitter Sent from my iPhone On Jul 27, 2013, at 11:17 AM, Michael Perrett mkperr...@gmail.com wrote: I have seen a lot of differing opinions on GPS Spoofing and using back up systems on this thread. Most pretty good, but a couple off the mark a bit. Here are a couple of comments on GPS Spoofing. - There are anti-spoofing GPS receivers available - to authorized users. Typically DOD. Most, if not all, military receivers utilize the encrypted P-Code, while civilians must use the more vulnerable clear text C/A code. The P-Code signals are very difficult to spoof unless you have a-pirori knowledge. The newer satellites (GPS III) will have an even more robust AS methodology. - Note: beware of P-Code, or Military, receivers available on eBay. They are useless without the encryption keys distributed by the US Government. - In the (near?) future there will be four civilian GPS Signals: The government is in the process of fielding three new signals designed for civilian use: L2C, L5, and L1C. The legacy civil signal, called L1 C/A or C/A at L1, will continue broadcasting in the future, for a total of four civil GPS signals. Users must upgrade their equipment to benefit from the new signals. ref http://www.gps.gov/systems/gps/modernization/civilsignals/ - Receivers utilizing the new civilian GPS frequencies can solve the GPS equations from more than one frequency and see if any one signal is being spoofed. The new civilian frequencies will be more spoof resistant. Comments on using inertial measurement units (IMUs) to back up GPS. - Current IMUs with even a good drift rate of say, 1 degree per hour, available for around a few thousand dollars, will be off 60 nautical miles after an hour of uncorrected operation. That can be reduced by other sensor inputs (GPS, LORAN, pit-log or what ever you have), but the navigation solution will eventually degrade to the accuracy of the external sensor. If my memory serves me for a really deep pocket navigator (having tens to hundreds of thousands of dollars, and a large amount of available mounting space) IMUs with drift rates of up to a thousand times less can be purchased (that's ,001 miles per hour, or around a couple of meters per hour), think submarines, etc. Using a dual sensor navigation system (or timing system! ), such as GPS/eLORAN, would obviously make the system so much more robust. Michael / K7HIL On Sat, Jul 27, 2013 at 6:43 AM, Scott McGrath scmcgr...@gmail.com wrote: Key here is how does the captain know that GPS is no longer providing an accurate fix? You need 2 or more independent
Re: [time-nuts] GPS Spoofing
Hi With a small jammer, you have a fast change in power vs distance. That's true regardless of frequency. The way Loran works, the jammer would do better if it looked like the low power slave for the area, not the highest power station. In both the case of Loran and GPS, you would need to get close by survey rather than DF. For a small area of impact, that's pretty much the same in both cases. Bob On Jul 27, 2013, at 10:00 PM, Scott McGrath scmcgr...@gmail.com wrote: Have you done any DF work with low chip rate spread spectrum signals down in the noise.It's not easy and you need to fft for the data A high power pulse train lots easier to DF Sent from my iPhone On Jul 27, 2013, at 3:44 PM, Bob Camp li...@rtty.us wrote: Hi A Loran jammer would / could work with a *much* smaller antenna if a local area was the target. Power is easy at 100 KHz. Loran is no easier / harder to DF than GPS. Bob On Jul 27, 2013, at 3:37 PM, Scott McGrath scmcgr...@gmail.com wrote: LORAN was/is not perfect geographic features could and did limit reception However an effective jammer would need effective power in the hundred watt range and a efficient antenna system plus a connection to power grid or small Genset. Not amenable to easy concealment and fairly easy to DF using standard techniques especially since location of real station well known and fixed An effective GPS jammer which can take out a few square miles is the size of a trade paperback and runs on batteries and costs under 50 bucks to build Imagine a scenario where a few hundred of these are deployed with hostile intent. Military and Civillian systems are now useless due to nature of signal they are hard to DF Sent from my iPhone On Jul 27, 2013, at 2:09 PM, Bob Camp li...@rtty.us wrote: Hi Loran can / could easily be jammed over a limited area, just like GPS. Nothing crazy large or expensive would be required. The same sort of malfunctioning this or that took out Loran from time to time over harbor sized areas. Loran had so many issues with dropping out, that they simply were not worth talking about …. Bob On Jul 27, 2013, at 1:35 PM, Scott McGrath scmcgr...@gmail.com wrote: Key Problem with GPS is its easy to spoof on one level and have a complete denial of service on the other. Out in California a while back a malfunctioning TV distribution amplifier jammed a major harbor and surrounding almost 25 sq miles affected all because of a 49.95 TV amp had a problem. The military receivers had the same problem LORAN is virtually jam proof unless you have a very powerful transmitter Sent from my iPhone On Jul 27, 2013, at 11:17 AM, Michael Perrett mkperr...@gmail.com wrote: I have seen a lot of differing opinions on GPS Spoofing and using back up systems on this thread. Most pretty good, but a couple off the mark a bit. Here are a couple of comments on GPS Spoofing. - There are anti-spoofing GPS receivers available - to authorized users. Typically DOD. Most, if not all, military receivers utilize the encrypted P-Code, while civilians must use the more vulnerable clear text C/A code. The P-Code signals are very difficult to spoof unless you have a-pirori knowledge. The newer satellites (GPS III) will have an even more robust AS methodology. - Note: beware of P-Code, or Military, receivers available on eBay. They are useless without the encryption keys distributed by the US Government. - In the (near?) future there will be four civilian GPS Signals: The government is in the process of fielding three new signals designed for civilian use: L2C, L5, and L1C. The legacy civil signal, called L1 C/A or C/A at L1, will continue broadcasting in the future, for a total of four civil GPS signals. Users must upgrade their equipment to benefit from the new signals. ref http://www.gps.gov/systems/gps/modernization/civilsignals/ - Receivers utilizing the new civilian GPS frequencies can solve the GPS equations from more than one frequency and see if any one signal is being spoofed. The new civilian frequencies will be more spoof resistant. Comments on using inertial measurement units (IMUs) to back up GPS. - Current IMUs with even a good drift rate of say, 1 degree per hour, available for around a few thousand dollars, will be off 60 nautical miles after an hour of uncorrected operation. That can be reduced by other sensor inputs (GPS, LORAN, pit-log or what ever you have), but the navigation solution will eventually degrade to the accuracy of the external sensor. If my memory serves me for a really deep pocket navigator (having tens to hundreds of thousands of dollars, and a large amount of available mounting space) IMUs with drift rates of up to a thousand times less can be purchased (that's ,001 miles per hour, or around a couple of meters per hour), think submarines, etc. Using a dual sensor navigation
Re: [time-nuts] More pictures of the mystery Collins Ru
maybe I should read things more often .. yikes I need a vacation On Sun, Jul 28, 2013 at 7:01 AM, George Dubovsky n4ua...@gmail.com wrote: Well, the outside label does claim it was made by GENRAD... ;-) 73, geo - n4ua On Sat, Jul 27, 2013 at 9:24 PM, Pete Lancashire p...@petelancashire.com wrote: https://plus.google.com/u/0/photos/111617808980322733757/albums/5890266601277045697 The board with the edge connector was inside the same bag the connector was in, the bag was taped to the unit. I pulled the ends off first, but was immediately stopped with foam, it is glued in place. Then when I finally got the lid with all the screws off, all there is, is one board covered in potting compound. The compound breaks away pretty easily. One can see where a couple parts were replaced and there soft RTV was used. There are two precision resistors in that area. The biggest surprise is the General Radio logo on the board ! goo.gl/1XGG2F ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] More pictures of the mystery Collins Ru
Googling a little bit, I find several references to a Collins rubidium package AFS-81 for airborne survivable VLF communications in the 60's (predating this unit by maybe two decades). Still trying to wrap my head around why that would need rubidium unless it was an airborne WWVB replacement or something. Googling also turned up the modern Rockwell-Collins 617A-1 VLF amp which seems to be a dinky solid state unit that is rated at a third of a megawatt. Still having a hard time wrapping my mind around that! Maybe I'm off by 2 or 3 orders of magnitude or the picture is just the control head, the real amplifier is the size of a building. A third of a megawatt must be the size of the fixed transmitters used for VLF submarine communications. Tim N3QE On Sun, Jul 28, 2013 at 9:40 AM, Pete Lancashire p...@petelancashire.comwrote: maybe I should read things more often .. yikes I need a vacation On Sun, Jul 28, 2013 at 7:01 AM, George Dubovsky n4ua...@gmail.com wrote: Well, the outside label does claim it was made by GENRAD... ;-) 73, geo - n4ua On Sat, Jul 27, 2013 at 9:24 PM, Pete Lancashire p...@petelancashire.com wrote: https://plus.google.com/u/0/photos/111617808980322733757/albums/5890266601277045697 The board with the edge connector was inside the same bag the connector was in, the bag was taped to the unit. I pulled the ends off first, but was immediately stopped with foam, it is glued in place. Then when I finally got the lid with all the screws off, all there is, is one board covered in potting compound. The compound breaks away pretty easily. One can see where a couple parts were replaced and there soft RTV was used. There are two precision resistors in that area. The biggest surprise is the General Radio logo on the board ! goo.gl/1XGG2F ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
I think the GPS backups are called, - GLONASS https://en.wikipedia.org/wiki/GLONASS - Galileohttps://en.wikipedia.org/wiki/Galileo_%28satellite_navigation%29 - IRNSShttps://en.wikipedia.org/wiki/Indian_Regional_Navigational_Satellite_System - Compass https://en.wikipedia.org/wiki/Compass_navigation_system They should all be up and running, especially the first two in 5 to 7 years. But ALL radio navigation systems can be spoofed. The ones you can't spoof are On Sun, Jul 28, 2013 at 2:03 AM, stew...@g3ysx.org.uk stew...@g3ysx.org.ukwrote: LF is much easier to accurately DF than VHF and above due to multipath effects. Stewart Sent from my iPad On 27 Jul 2013, at 21:44, Bob Camp li...@rtty.us wrote: Hi A Loran jammer would / could work with a *much* smaller antenna if a local area was the target. Power is easy at 100 KHz. Loran is no easier / harder to DF than GPS. Bob On Jul 27, 2013, at 3:37 PM, Scott McGrath scmcgr...@gmail.com wrote: LORAN was/is not perfect geographic features could and did limit reception However an effective jammer would need effective power in the hundred watt range and a efficient antenna system plus a connection to power grid or small Genset. Not amenable to easy concealment and fairly easy to DF using standard techniques especially since location of real station well known and fixed An effective GPS jammer which can take out a few square miles is the size of a trade paperback and runs on batteries and costs under 50 bucks to build Imagine a scenario where a few hundred of these are deployed with hostile intent. Military and Civillian systems are now useless due to nature of signal they are hard to DF Sent from my iPhone On Jul 27, 2013, at 2:09 PM, Bob Camp li...@rtty.us wrote: Hi Loran can / could easily be jammed over a limited area, just like GPS. Nothing crazy large or expensive would be required. The same sort of malfunctioning this or that took out Loran from time to time over harbor sized areas. Loran had so many issues with dropping out, that they simply were not worth talking about …. Bob On Jul 27, 2013, at 1:35 PM, Scott McGrath scmcgr...@gmail.com wrote: Key Problem with GPS is its easy to spoof on one level and have a complete denial of service on the other. Out in California a while back a malfunctioning TV distribution amplifier jammed a major harbor and surrounding almost 25 sq miles affected all because of a 49.95 TV amp had a problem. The military receivers had the same problem LORAN is virtually jam proof unless you have a very powerful transmitter Sent from my iPhone On Jul 27, 2013, at 11:17 AM, Michael Perrett mkperr...@gmail.com wrote: I have seen a lot of differing opinions on GPS Spoofing and using back up systems on this thread. Most pretty good, but a couple off the mark a bit. Here are a couple of comments on GPS Spoofing. - There are anti-spoofing GPS receivers available - to authorized users. Typically DOD. Most, if not all, military receivers utilize the encrypted P-Code, while civilians must use the more vulnerable clear text C/A code. The P-Code signals are very difficult to spoof unless you have a-pirori knowledge. The newer satellites (GPS III) will have an even more robust AS methodology. - Note: beware of P-Code, or Military, receivers available on eBay. They are useless without the encryption keys distributed by the US Government. - In the (near?) future there will be four civilian GPS Signals: The government is in the process of fielding three new signals designed for civilian use: L2C, L5, and L1C. The legacy civil signal, called L1 C/A or C/A at L1, will continue broadcasting in the future, for a total of four civil GPS signals. Users must upgrade their equipment to benefit from the new signals. ref http://www.gps.gov/systems/gps/modernization/civilsignals/ - Receivers utilizing the new civilian GPS frequencies can solve the GPS equations from more than one frequency and see if any one signal is being spoofed. The new civilian frequencies will be more spoof resistant. Comments on using inertial measurement units (IMUs) to back up GPS. - Current IMUs with even a good drift rate of say, 1 degree per hour, available for around a few thousand dollars, will be off 60 nautical miles after an hour of uncorrected operation. That can be reduced by other sensor inputs (GPS, LORAN, pit-log or what ever you have), but the navigation solution will eventually degrade to the accuracy of the external sensor. If my memory serves me for a really deep pocket navigator (having tens to hundreds of thousands of dollars, and a large amount of available mounting space) IMUs with drift rates of up to a thousand times less can be purchased (that's ,001 miles per hour, or around a couple of meters per hour), think submarines, etc.
Re: [time-nuts] More pictures of the mystery Collins Ru
Hi Tim, Three possible reasons for needing a Rb standard, 1/ Coherent detection with a local clock 2/ Hyperbolic navigation (local reference improves the fix and holdover) 3/ Secure communications. Robert G8RPI From: Tim Shoppa tsho...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, 28 July 2013, 15:25 Subject: Re: [time-nuts] More pictures of the mystery Collins Ru Googling a little bit, I find several references to a Collins rubidium package AFS-81 for airborne survivable VLF communications in the 60's (predating this unit by maybe two decades). Still trying to wrap my head around why that would need rubidium unless it was an airborne WWVB replacement or something. Googling also turned up the modern Rockwell-Collins 617A-1 VLF amp which seems to be a dinky solid state unit that is rated at a third of a megawatt. Still having a hard time wrapping my mind around that! Maybe I'm off by 2 or 3 orders of magnitude or the picture is just the control head, the real amplifier is the size of a building. A third of a megawatt must be the size of the fixed transmitters used for VLF submarine communications. Tim N3QE On Sun, Jul 28, 2013 at 9:40 AM, Pete Lancashire p...@petelancashire.comwrote: maybe I should read things more often .. yikes I need a vacation On Sun, Jul 28, 2013 at 7:01 AM, George Dubovsky n4ua...@gmail.com wrote: Well, the outside label does claim it was made by GENRAD... ;-) 73, geo - n4ua On Sat, Jul 27, 2013 at 9:24 PM, Pete Lancashire p...@petelancashire.com wrote: https://plus.google.com/u/0/photos/111617808980322733757/albums/5890266601277045697 The board with the edge connector was inside the same bag the connector was in, the bag was taped to the unit. I pulled the ends off first, but was immediately stopped with foam, it is glued in place. Then when I finally got the lid with all the screws off, all there is, is one board covered in potting compound. The compound breaks away pretty easily. One can see where a couple parts were replaced and there soft RTV was used. There are two precision resistors in that area. The biggest surprise is the General Radio logo on the board ! goo.gl/1XGG2F ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
In message cabbxvhsqjbbtpc0wcx3k3e3i2xrk797doyhxnmb8bfluk5b...@mail.gmail.com , Chris Albertson writes: I think the GPS backups are called, None of those are usable as backups for GPS, as they use the same low-power Microwave signals as GPS. But ALL radio navigation systems can be spoofed. The ones you can't spoof are Loran-C. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
Yes it is and it can be done with simple loop stick antennas. Prior to wide use of loran ships would use LF beacons and DF receivers either manual automatic Periodically you will see shortwave receivers with a rotating antenna and a bearing ring you would find a bearing to a couple of beacon or broadcast station and calculate position based on triangulation Basically a radio version of a pelorus Sent from my iPhone On Jul 28, 2013, at 5:03 AM, stew...@g3ysx.org.uk stew...@g3ysx.org.uk wrote: LF is much easier to accurately DF than VHF and above due to multipath effects. Stewart Sent from my iPad On 27 Jul 2013, at 21:44, Bob Camp li...@rtty.us wrote: Hi A Loran jammer would / could work with a *much* smaller antenna if a local area was the target. Power is easy at 100 KHz. Loran is no easier / harder to DF than GPS. Bob On Jul 27, 2013, at 3:37 PM, Scott McGrath scmcgr...@gmail.com wrote: LORAN was/is not perfect geographic features could and did limit reception However an effective jammer would need effective power in the hundred watt range and a efficient antenna system plus a connection to power grid or small Genset. Not amenable to easy concealment and fairly easy to DF using standard techniques especially since location of real station well known and fixed An effective GPS jammer which can take out a few square miles is the size of a trade paperback and runs on batteries and costs under 50 bucks to build Imagine a scenario where a few hundred of these are deployed with hostile intent. Military and Civillian systems are now useless due to nature of signal they are hard to DF Sent from my iPhone On Jul 27, 2013, at 2:09 PM, Bob Camp li...@rtty.us wrote: Hi Loran can / could easily be jammed over a limited area, just like GPS. Nothing crazy large or expensive would be required. The same sort of malfunctioning this or that took out Loran from time to time over harbor sized areas. Loran had so many issues with dropping out, that they simply were not worth talking about …. Bob On Jul 27, 2013, at 1:35 PM, Scott McGrath scmcgr...@gmail.com wrote: Key Problem with GPS is its easy to spoof on one level and have a complete denial of service on the other. Out in California a while back a malfunctioning TV distribution amplifier jammed a major harbor and surrounding almost 25 sq miles affected all because of a 49.95 TV amp had a problem. The military receivers had the same problem LORAN is virtually jam proof unless you have a very powerful transmitter Sent from my iPhone On Jul 27, 2013, at 11:17 AM, Michael Perrett mkperr...@gmail.com wrote: I have seen a lot of differing opinions on GPS Spoofing and using back up systems on this thread. Most pretty good, but a couple off the mark a bit. Here are a couple of comments on GPS Spoofing. - There are anti-spoofing GPS receivers available - to authorized users. Typically DOD. Most, if not all, military receivers utilize the encrypted P-Code, while civilians must use the more vulnerable clear text C/A code. The P-Code signals are very difficult to spoof unless you have a-pirori knowledge. The newer satellites (GPS III) will have an even more robust AS methodology. - Note: beware of P-Code, or Military, receivers available on eBay. They are useless without the encryption keys distributed by the US Government. - In the (near?) future there will be four civilian GPS Signals: The government is in the process of fielding three new signals designed for civilian use: L2C, L5, and L1C. The legacy civil signal, called L1 C/A or C/A at L1, will continue broadcasting in the future, for a total of four civil GPS signals. Users must upgrade their equipment to benefit from the new signals. ref http://www.gps.gov/systems/gps/modernization/civilsignals/ - Receivers utilizing the new civilian GPS frequencies can solve the GPS equations from more than one frequency and see if any one signal is being spoofed. The new civilian frequencies will be more spoof resistant. Comments on using inertial measurement units (IMUs) to back up GPS. - Current IMUs with even a good drift rate of say, 1 degree per hour, available for around a few thousand dollars, will be off 60 nautical miles after an hour of uncorrected operation. That can be reduced by other sensor inputs (GPS, LORAN, pit-log or what ever you have), but the navigation solution will eventually degrade to the accuracy of the external sensor. If my memory serves me for a really deep pocket navigator (having tens to hundreds of thousands of dollars, and a large amount of available mounting space) IMUs with drift rates of up to a thousand times less can be purchased (that's ,001 miles per hour, or around a couple of meters per hour), think submarines, etc. Using a dual sensor navigation system (or timing system! ), such as GPS/eLORAN, would obviously
Re: [time-nuts] GPS Spoofing
Hi Except a rotating rod antenna gives you only a bearing, not a direction. At VHF and above you can use multiple antennas and directly get a bearing. Much faster and easier to automate. Bob On Jul 28, 2013, at 11:53 AM, Scott McGrath scmcgr...@gmail.com wrote: Yes it is and it can be done with simple loop stick antennas. Prior to wide use of loran ships would use LF beacons and DF receivers either manual automatic Periodically you will see shortwave receivers with a rotating antenna and a bearing ring you would find a bearing to a couple of beacon or broadcast station and calculate position based on triangulation Basically a radio version of a pelorus Sent from my iPhone On Jul 28, 2013, at 5:03 AM, stew...@g3ysx.org.uk stew...@g3ysx.org.uk wrote: LF is much easier to accurately DF than VHF and above due to multipath effects. Stewart Sent from my iPad On 27 Jul 2013, at 21:44, Bob Camp li...@rtty.us wrote: Hi A Loran jammer would / could work with a *much* smaller antenna if a local area was the target. Power is easy at 100 KHz. Loran is no easier / harder to DF than GPS. Bob On Jul 27, 2013, at 3:37 PM, Scott McGrath scmcgr...@gmail.com wrote: LORAN was/is not perfect geographic features could and did limit reception However an effective jammer would need effective power in the hundred watt range and a efficient antenna system plus a connection to power grid or small Genset. Not amenable to easy concealment and fairly easy to DF using standard techniques especially since location of real station well known and fixed An effective GPS jammer which can take out a few square miles is the size of a trade paperback and runs on batteries and costs under 50 bucks to build Imagine a scenario where a few hundred of these are deployed with hostile intent. Military and Civillian systems are now useless due to nature of signal they are hard to DF Sent from my iPhone On Jul 27, 2013, at 2:09 PM, Bob Camp li...@rtty.us wrote: Hi Loran can / could easily be jammed over a limited area, just like GPS. Nothing crazy large or expensive would be required. The same sort of malfunctioning this or that took out Loran from time to time over harbor sized areas. Loran had so many issues with dropping out, that they simply were not worth talking about …. Bob On Jul 27, 2013, at 1:35 PM, Scott McGrath scmcgr...@gmail.com wrote: Key Problem with GPS is its easy to spoof on one level and have a complete denial of service on the other. Out in California a while back a malfunctioning TV distribution amplifier jammed a major harbor and surrounding almost 25 sq miles affected all because of a 49.95 TV amp had a problem. The military receivers had the same problem LORAN is virtually jam proof unless you have a very powerful transmitter Sent from my iPhone On Jul 27, 2013, at 11:17 AM, Michael Perrett mkperr...@gmail.com wrote: I have seen a lot of differing opinions on GPS Spoofing and using back up systems on this thread. Most pretty good, but a couple off the mark a bit. Here are a couple of comments on GPS Spoofing. - There are anti-spoofing GPS receivers available - to authorized users. Typically DOD. Most, if not all, military receivers utilize the encrypted P-Code, while civilians must use the more vulnerable clear text C/A code. The P-Code signals are very difficult to spoof unless you have a-pirori knowledge. The newer satellites (GPS III) will have an even more robust AS methodology. - Note: beware of P-Code, or Military, receivers available on eBay. They are useless without the encryption keys distributed by the US Government. - In the (near?) future there will be four civilian GPS Signals: The government is in the process of fielding three new signals designed for civilian use: L2C, L5, and L1C. The legacy civil signal, called L1 C/A or C/A at L1, will continue broadcasting in the future, for a total of four civil GPS signals. Users must upgrade their equipment to benefit from the new signals. ref http://www.gps.gov/systems/gps/modernization/civilsignals/ - Receivers utilizing the new civilian GPS frequencies can solve the GPS equations from more than one frequency and see if any one signal is being spoofed. The new civilian frequencies will be more spoof resistant. Comments on using inertial measurement units (IMUs) to back up GPS. - Current IMUs with even a good drift rate of say, 1 degree per hour, available for around a few thousand dollars, will be off 60 nautical miles after an hour of uncorrected operation. That can be reduced by other sensor inputs (GPS, LORAN, pit-log or what ever you have), but the navigation solution will eventually degrade to the accuracy of the external sensor. If my memory serves me for a really deep pocket navigator (having tens to hundreds of thousands of dollars, and a large
Re: [time-nuts] GPS Spoofing
Hi …. and if a pulse comes up *looking* like the slave …. Loran-C wanders around enough all by it's self, with no need for help from others. Bumping it a bit this way or that is not an impossibility. A little bit of added phase this way or that is all it would take. You would have to get the rep rate and timing right, but that's just the sort of thing a Time Nut knows how to do on the cheap. Bob On Jul 28, 2013, at 11:55 AM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message cabbxvhsqjbbtpc0wcx3k3e3i2xrk797doyhxnmb8bfluk5b...@mail.gmail.com , Chris Albertson writes: I think the GPS backups are called, None of those are usable as backups for GPS, as they use the same low-power Microwave signals as GPS. But ALL radio navigation systems can be spoofed. The ones you can't spoof are Loran-C. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
In message 26bb6f2a-69ac-4587-8057-ba18a03e8...@rtty.us, Bob Camp writes: Bumping it a bit this way or that is not an impossibility. A little bit of added phase this way or that is all it would take. You would have to get the rep rate and timing right, but that's just the sort of thing a Time Nut knows how to do on the cheap. Only its not actually possible in practice. The problem with GNSS is that the kit to jam/spoof is sub-suitcase-sized. To jam/spoof LORAN-C or any other VLF system, you need several trucks: One for the generator, one for the antenna -- at least. That's the reason why LORSTA's have 600' antenna towers to begin with. LORAN-C may not be as precise, but it is very stable, which means that your dual-source nav-kit will tell you that GPS and LORAN-C diverges in ways that looks odd... The reason why we still have LORAN-C in europe, is that UK and France don't trust DoD to not play with GPS. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
Key is GPS is EASY to deny for wide areas for both Civillian and military users Loran much less so and eLoran even less due to information carried by signal. And the larger the area attacked the jammer becomes easier to find due to signal strength There is no doubt that both systems can be spoofed by a sophisticated attacker. It's just that GPS can be nullified by jammers which are available at most truck and spy shops for under 200 bucks. Legality notwithstanding Sent from my iPhone On Jul 28, 2013, at 12:28 PM, Bob Camp li...@rtty.us wrote: Hi …. and if a pulse comes up *looking* like the slave …. Loran-C wanders around enough all by it's self, with no need for help from others. Bumping it a bit this way or that is not an impossibility. A little bit of added phase this way or that is all it would take. You would have to get the rep rate and timing right, but that's just the sort of thing a Time Nut knows how to do on the cheap. Bob On Jul 28, 2013, at 11:55 AM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message cabbxvhsqjbbtpc0wcx3k3e3i2xrk797doyhxnmb8bfluk5b...@mail.gmail.com , Chris Albertson writes: I think the GPS backups are called, None of those are usable as backups for GPS, as they use the same low-power Microwave signals as GPS. But ALL radio navigation systems can be spoofed. The ones you can't spoof are Loran-C. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
Hi I'm not talking about taking out Loran-C over the entire North Atlantic. The target is a harbor sized area. For that, you certainly do not need a 600' antenna or megawatts of power. You only need to generate a near field signal, not set up something that will propagate beyond line of sight. There are a couple of ways that the antenna could be done. Long term, Loran-C is reasonably stable *if* the propagation is over water. If it's over land (as with most of the US chains) it's not as stable. A bit of drift from time to time was indeed very much expected. Great for getting back to last month's fishing spot, not quite so great for getting back to one from many years ago. Bob On Jul 28, 2013, at 1:00 PM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message 26bb6f2a-69ac-4587-8057-ba18a03e8...@rtty.us, Bob Camp writes: Bumping it a bit this way or that is not an impossibility. A little bit of added phase this way or that is all it would take. You would have to get the rep rate and timing right, but that's just the sort of thing a Time Nut knows how to do on the cheap. Only its not actually possible in practice. The problem with GNSS is that the kit to jam/spoof is sub-suitcase-sized. To jam/spoof LORAN-C or any other VLF system, you need several trucks: One for the generator, one for the antenna -- at least. That's the reason why LORSTA's have 600' antenna towers to begin with. LORAN-C may not be as precise, but it is very stable, which means that your dual-source nav-kit will tell you that GPS and LORAN-C diverges in ways that looks odd... The reason why we still have LORAN-C in europe, is that UK and France don't trust DoD to not play with GPS. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
Hi If we are now down to a truck sized / house sized area, I'd claim that Loran-C is dead simple to jam. That's what the truck stop gizmos are aimed at. Bob On Jul 28, 2013, at 1:09 PM, Scott McGrath scmcgr...@gmail.com wrote: Key is GPS is EASY to deny for wide areas for both Civillian and military users Loran much less so and eLoran even less due to information carried by signal. And the larger the area attacked the jammer becomes easier to find due to signal strength There is no doubt that both systems can be spoofed by a sophisticated attacker. It's just that GPS can be nullified by jammers which are available at most truck and spy shops for under 200 bucks. Legality notwithstanding Sent from my iPhone On Jul 28, 2013, at 12:28 PM, Bob Camp li...@rtty.us wrote: Hi …. and if a pulse comes up *looking* like the slave …. Loran-C wanders around enough all by it's self, with no need for help from others. Bumping it a bit this way or that is not an impossibility. A little bit of added phase this way or that is all it would take. You would have to get the rep rate and timing right, but that's just the sort of thing a Time Nut knows how to do on the cheap. Bob On Jul 28, 2013, at 11:55 AM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message cabbxvhsqjbbtpc0wcx3k3e3i2xrk797doyhxnmb8bfluk5b...@mail.gmail.com , Chris Albertson writes: I think the GPS backups are called, None of those are usable as backups for GPS, as they use the same low-power Microwave signals as GPS. But ALL radio navigation systems can be spoofed. The ones you can't spoof are Loran-C. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
In message 581a0abf-19d8-45bb-88c3-cb351711b...@rtty.us, Bob Camp writes: If we are now down to a truck sized / house sized area, I'd claim that Loran-C is dead simple to jam. That's what the truck stop gizmos are aimed at. We are not. You don't get to place your Loran-C jamming car right next to the supertanker or cruise-ghetto, nor will any major airline allow your semi/van to emit EMI from the parking-lot for long. The problem with GNSS is that you need so little power and antenna to deny such a large area. VLF just doesn't suffer from that. And now that US killed their LORAN, maybe we should apply some modern signal-theory and design a new and even more robust VLF signal... -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
In message dab33aef-98ef-4503-89a7-657f0d25a...@rtty.us, Bob Camp writes: I'm not talking about taking out Loran-C over the entire North Atlantic. The target is a harbor sized area. For that, you certainly do not need a 600' antenna or megawatts of power. No, you need about 600W (continuous) and a loop-antenna about 5m in diameter. Do the math, It's not as easy as you think. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] More pictures of the mystery Collins Ru
Hi: I think (3). See: http://en.wikipedia.org/wiki/TACAMO http://en.wikipedia.org/wiki/Ground_Wave_Emergency_Network - some converted to DGPS Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html Robert Atkinson wrote: Hi Tim, Three possible reasons for needing a Rb standard, 1/ Coherent detection with a local clock 2/ Hyperbolic navigation (local reference improves the fix and holdover) 3/ Secure communications. Robert G8RPI From: Tim Shoppa tsho...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, 28 July 2013, 15:25 Subject: Re: [time-nuts] More pictures of the mystery Collins Ru Googling a little bit, I find several references to a Collins rubidium package AFS-81 for airborne survivable VLF communications in the 60's (predating this unit by maybe two decades). Still trying to wrap my head around why that would need rubidium unless it was an airborne WWVB replacement or something. Googling also turned up the modern Rockwell-Collins 617A-1 VLF amp which seems to be a dinky solid state unit that is rated at a third of a megawatt. Still having a hard time wrapping my mind around that! Maybe I'm off by 2 or 3 orders of magnitude or the picture is just the control head, the real amplifier is the size of a building. A third of a megawatt must be the size of the fixed transmitters used for VLF submarine communications. Tim N3QE On Sun, Jul 28, 2013 at 9:40 AM, Pete Lancashire p...@petelancashire.comwrote: maybe I should read things more often .. yikes I need a vacation On Sun, Jul 28, 2013 at 7:01 AM, George Dubovsky n4ua...@gmail.com wrote: Well, the outside label does claim it was made by GENRAD... ;-) 73, geo - n4ua On Sat, Jul 27, 2013 at 9:24 PM, Pete Lancashire p...@petelancashire.com wrote: https://plus.google.com/u/0/photos/111617808980322733757/albums/5890266601277045697 The board with the edge connector was inside the same bag the connector was in, the bag was taped to the unit. I pulled the ends off first, but was immediately stopped with foam, it is glued in place. Then when I finally got the lid with all the screws off, all there is, is one board covered in potting compound. The compound breaks away pretty easily. One can see where a couple parts were replaced and there soft RTV was used. There are two precision resistors in that area. The biggest surprise is the General Radio logo on the board ! goo.gl/1XGG2F ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
Hi Since it's a pulse system, and you get to position your pulse for maximum effect, I don't see any reason to generate CW power. Simply mimic the lowest power slave in the chain. There's very little redundancy with Loran, so spoofing one station will mess it up. No need to mask the entire chain. At most you would need to hit two low power slaves. Math wise: Wavelength is 10,000 ft / 3,000M. Throw things off by ~10% of that and you have problems in a harbor. You would need to play a bit to see weather a pulse every so often does the trick or not. Is that 20 db below the slave or not ? You'd have to play with it. It's in that range. A spoof that says they are on the other side of the world isn't going to work. One that says you are on the north side of the channel (when you are on the south side) is what would work. Power within a pulse set at a 5:1 duty cycle. For a 50,000 us GRI you have another 50:1. For longer GRI's you might add another 2:1. Net is a peak to average ratio of 250-1000 to 1. Put another way, a 500W pulse is ~ 1 average. Power at 100 KHz = what's in a fairly cheap switching power supply. Plug it into the wall. A couple hundred watts (or even KW) pulse is cheap. Say you have 120W out of the wall (or a car battery). If the math above is correct and you can run 80% efficiency, that's a pretty powerful pulse. It's probably cheaper to generate something at 50:1 rather than the whole 200:1. A 5KW is a *lot* of RF, even into a simple antenna. Antenna - there's a couple ways to do that. All of them are tradeoffs (size / cost / power). The cheap way is to use a wire that's already there…. Since you don't need to propagate (near field), the antenna efficiency could be higher than you would think for some antennas. Is it easier than that with some smarts involved in the pulse - probably yes. Do the smarts raise the hardware cost significantly? - you'd have to build a few and find out. What really drives this or that Loran receiver nuts? I'm quite sure you could work that out with one to play with. Am I gong into the Loran-C jammer business? No, so don't contact me off list to buy one. The point is not *have* I built one, but could one be built easily. Bob On Jul 28, 2013, at 1:29 PM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message dab33aef-98ef-4503-89a7-657f0d25a...@rtty.us, Bob Camp writes: I'm not talking about taking out Loran-C over the entire North Atlantic. The target is a harbor sized area. For that, you certainly do not need a 600' antenna or megawatts of power. No, you need about 600W (continuous) and a loop-antenna about 5m in diameter. Do the math, It's not as easy as you think. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
The point about the duty cycle being low is correct. And, there are commercial linear power amps, like the used ones made by ENI and others, that can easily put out 1 kW plus narrow pulses. Furthermore, the pulse generator is trivial to make with a Rb, 3 or more Tektronix DD501s, a simple OR gate and a gated oscillator at about 100 kHz. I've cobbled up that setup several times as a LORAN-A simulator. The main difficulty is getting a reasonable match to an efficient antenna at 100 kHz. -John = Hi Since it's a pulse system, and you get to position your pulse for maximum effect, I don't see any reason to generate CW power. Simply mimic the lowest power slave in the chain. There's very little redundancy with Loran, so spoofing one station will mess it up. No need to mask the entire chain. At most you would need to hit two low power slaves. Math wise: Wavelength is 10,000 ft / 3,000M. Throw things off by ~10% of that and you have problems in a harbor. You would need to play a bit to see weather a pulse every so often does the trick or not. Is that 20 db below the slave or not ? You'd have to play with it. It's in that range. A spoof that says they are on the other side of the world isn't going to work. One that says you are on the north side of the channel (when you are on the south side) is what would work. Power within a pulse set at a 5:1 duty cycle. For a 50,000 us GRI you have another 50:1. For longer GRI's you might add another 2:1. Net is a peak to average ratio of 250-1000 to 1. Put another way, a 500W pulse is ~ 1 average. Power at 100 KHz = what's in a fairly cheap switching power supply. Plug it into the wall. A couple hundred watts (or even KW) pulse is cheap. Say you have 120W out of the wall (or a car battery). If the math above is correct and you can run 80% efficiency, that's a pretty powerful pulse. It's probably cheaper to generate something at 50:1 rather than the whole 200:1. A 5KW is a *lot* of RF, even into a simple antenna. Antenna - there's a couple ways to do that. All of them are tradeoffs (size / cost / power). The cheap way is to use a wire that's already there . Since you don't need to propagate (near field), the antenna efficiency could be higher than you would think for some antennas. Is it easier than that with some smarts involved in the pulse - probably yes. Do the smarts raise the hardware cost significantly? - you'd have to build a few and find out. What really drives this or that Loran receiver nuts? I'm quite sure you could work that out with one to play with. Am I gong into the Loran-C jammer business? No, so don't contact me off list to buy one. The point is not *have* I built one, but could one be built easily. Bob On Jul 28, 2013, at 1:29 PM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message dab33aef-98ef-4503-89a7-657f0d25a...@rtty.us, Bob Camp writes: I'm not talking about taking out Loran-C over the entire North Atlantic. The target is a harbor sized area. For that, you certainly do not need a 600' antenna or megawatts of power. No, you need about 600W (continuous) and a loop-antenna about 5m in diameter. Do the math, It's not as easy as you think. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
I've just been catching up on this thread. The subject says GPS Spoofing, but most of the replies seem to revolve around jamming. Not the same thing. Just a thought... Rob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of J. Forster Sent: 28 July 2013 20:06 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] GPS Spoofing The point about the duty cycle being low is correct. And, there are commercial linear power amps, like the used ones made by ENI and others, that can easily put out 1 kW plus narrow pulses. Furthermore, the pulse generator is trivial to make with a Rb, 3 or more Tektronix DD501s, a simple OR gate and a gated oscillator at about 100 kHz. I've cobbled up that setup several times as a LORAN-A simulator. The main difficulty is getting a reasonable match to an efficient antenna at 100 kHz. -John = Hi Since it's a pulse system, and you get to position your pulse for maximum effect, I don't see any reason to generate CW power. Simply mimic the lowest power slave in the chain. There's very little redundancy with Loran, so spoofing one station will mess it up. No need to mask the entire chain. At most you would need to hit two low power slaves. Math wise: Wavelength is 10,000 ft / 3,000M. Throw things off by ~10% of that and you have problems in a harbor. You would need to play a bit to see weather a pulse every so often does the trick or not. Is that 20 db below the slave or not ? You'd have to play with it. It's in that range. A spoof that says they are on the other side of the world isn't going to work. One that says you are on the north side of the channel (when you are on the south side) is what would work. Power within a pulse set at a 5:1 duty cycle. For a 50,000 us GRI you have another 50:1. For longer GRI's you might add another 2:1. Net is a peak to average ratio of 250-1000 to 1. Put another way, a 500W pulse is ~ 1 average. Power at 100 KHz = what's in a fairly cheap switching power supply. Plug it into the wall. A couple hundred watts (or even KW) pulse is cheap. Say you have 120W out of the wall (or a car battery). If the math above is correct and you can run 80% efficiency, that's a pretty powerful pulse. It's probably cheaper to generate something at 50:1 rather than the whole 200:1. A 5KW is a *lot* of RF, even into a simple antenna. Antenna - there's a couple ways to do that. All of them are tradeoffs (size / cost / power). The cheap way is to use a wire that's already there.. Since you don't need to propagate (near field), the antenna efficiency could be higher than you would think for some antennas. Is it easier than that with some smarts involved in the pulse - probably yes. Do the smarts raise the hardware cost significantly? - you'd have to build a few and find out. What really drives this or that Loran receiver nuts? I'm quite sure you could work that out with one to play with. Am I gong into the Loran-C jammer business? No, so don't contact me off list to buy one. The point is not *have* I built one, but could one be built easily. Bob On Jul 28, 2013, at 1:29 PM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message dab33aef-98ef-4503-89a7-657f0d25a...@rtty.us, Bob Camp writes: I'm not talking about taking out Loran-C over the entire North Atlantic. The target is a harbor sized area. For that, you certainly do not need a 600' antenna or megawatts of power. No, you need about 600W (continuous) and a loop-antenna about 5m in diameter. Do the math, It's not as easy as you think. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
Not so at all. What I described is a simple means to make a receiver see different GRIs and TDs than what it might see off the air. The system can accurately set any GRI in 1 uS increments and any one of several TDs to 1 uS also. That is hardly a jammer. Furthermore, if the Tek DD501s were replaced by something like BNC programmable Digital Delays, you could change the received position over time. -John I've just been catching up on this thread. The subject says GPS Spoofing, but most of the replies seem to revolve around jamming. Not the same thing. Just a thought... Rob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of J. Forster Sent: 28 July 2013 20:06 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] GPS Spoofing The point about the duty cycle being low is correct. And, there are commercial linear power amps, like the used ones made by ENI and others, that can easily put out 1 kW plus narrow pulses. Furthermore, the pulse generator is trivial to make with a Rb, 3 or more Tektronix DD501s, a simple OR gate and a gated oscillator at about 100 kHz. I've cobbled up that setup several times as a LORAN-A simulator. The main difficulty is getting a reasonable match to an efficient antenna at 100 kHz. -John = Hi Since it's a pulse system, and you get to position your pulse for maximum effect, I don't see any reason to generate CW power. Simply mimic the lowest power slave in the chain. There's very little redundancy with Loran, so spoofing one station will mess it up. No need to mask the entire chain. At most you would need to hit two low power slaves. Math wise: Wavelength is 10,000 ft / 3,000M. Throw things off by ~10% of that and you have problems in a harbor. You would need to play a bit to see weather a pulse every so often does the trick or not. Is that 20 db below the slave or not ? You'd have to play with it. It's in that range. A spoof that says they are on the other side of the world isn't going to work. One that says you are on the north side of the channel (when you are on the south side) is what would work. Power within a pulse set at a 5:1 duty cycle. For a 50,000 us GRI you have another 50:1. For longer GRI's you might add another 2:1. Net is a peak to average ratio of 250-1000 to 1. Put another way, a 500W pulse is ~ 1 average. Power at 100 KHz = what's in a fairly cheap switching power supply. Plug it into the wall. A couple hundred watts (or even KW) pulse is cheap. Say you have 120W out of the wall (or a car battery). If the math above is correct and you can run 80% efficiency, that's a pretty powerful pulse. It's probably cheaper to generate something at 50:1 rather than the whole 200:1. A 5KW is a *lot* of RF, even into a simple antenna. Antenna - there's a couple ways to do that. All of them are tradeoffs (size / cost / power). The cheap way is to use a wire that's already there.. Since you don't need to propagate (near field), the antenna efficiency could be higher than you would think for some antennas. Is it easier than that with some smarts involved in the pulse - probably yes. Do the smarts raise the hardware cost significantly? - you'd have to build a few and find out. What really drives this or that Loran receiver nuts? I'm quite sure you could work that out with one to play with. Am I gong into the Loran-C jammer business? No, so don't contact me off list to buy one. The point is not *have* I built one, but could one be built easily. Bob On Jul 28, 2013, at 1:29 PM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message dab33aef-98ef-4503-89a7-657f0d25a...@rtty.us, Bob Camp writes: I'm not talking about taking out Loran-C over the entire North Atlantic. The target is a harbor sized area. For that, you certainly do not need a 600' antenna or megawatts of power. No, you need about 600W (continuous) and a loop-antenna about 5m in diameter. Do the math, It's not as easy as you think. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
Hi My antenna design relies mainly on a near field / far field argument. In normal antenna design, the only thing that counts is the far field. You calculate the near field mainly to get drive point impedances. In this case you are within 1/10 wavelength of the antenna. The near field energy counts in this case. Propagation at 100 KHz is indeed polarization dependent. You also do not care about weather your antenna is horizontally or vertically polarized. One obvious design is a loop. It could be small, but quite high current. It could be larger / lower current. Switchers are often good at moving a lot of current into low impedances. Your amp might like a low impedance / high current load. Put another way - your amp may match to 1 ohm. Think of a 3.3V 100A switcher. Look especially at the sorts of currents inside the switching loop. Very much *not* a 50 ohm system. Another design goes entirely the other way. Back feed the power lines. Horizontal polarization won't propagate, but that's not the issue. Impedance is low (yes I have measured it), so it's still a high current drive situation. Having the signal spread all over the neighborhood would be the main benefit. Are either of these great antennas? No, of course not. For that matter a 600' vertical isn't all that good an antenna at 100 KHz. That great big antenna is likely 200 to 600 miles away. Again, we're not trying to jam the system, only to spoof it by a bit. You don't need to drown out the slave transmitter. You just need to get the signals to add phase. Bob On Jul 28, 2013, at 3:06 PM, J. Forster j...@quikus.com wrote: The point about the duty cycle being low is correct. And, there are commercial linear power amps, like the used ones made by ENI and others, that can easily put out 1 kW plus narrow pulses. Furthermore, the pulse generator is trivial to make with a Rb, 3 or more Tektronix DD501s, a simple OR gate and a gated oscillator at about 100 kHz. I've cobbled up that setup several times as a LORAN-A simulator. The main difficulty is getting a reasonable match to an efficient antenna at 100 kHz. -John = Hi Since it's a pulse system, and you get to position your pulse for maximum effect, I don't see any reason to generate CW power. Simply mimic the lowest power slave in the chain. There's very little redundancy with Loran, so spoofing one station will mess it up. No need to mask the entire chain. At most you would need to hit two low power slaves. Math wise: Wavelength is 10,000 ft / 3,000M. Throw things off by ~10% of that and you have problems in a harbor. You would need to play a bit to see weather a pulse every so often does the trick or not. Is that 20 db below the slave or not ? You'd have to play with it. It's in that range. A spoof that says they are on the other side of the world isn't going to work. One that says you are on the north side of the channel (when you are on the south side) is what would work. Power within a pulse set at a 5:1 duty cycle. For a 50,000 us GRI you have another 50:1. For longer GRI's you might add another 2:1. Net is a peak to average ratio of 250-1000 to 1. Put another way, a 500W pulse is ~ 1 average. Power at 100 KHz = what's in a fairly cheap switching power supply. Plug it into the wall. A couple hundred watts (or even KW) pulse is cheap. Say you have 120W out of the wall (or a car battery). If the math above is correct and you can run 80% efficiency, that's a pretty powerful pulse. It's probably cheaper to generate something at 50:1 rather than the whole 200:1. A 5KW is a *lot* of RF, even into a simple antenna. Antenna - there's a couple ways to do that. All of them are tradeoffs (size / cost / power). The cheap way is to use a wire that's already there…. Since you don't need to propagate (near field), the antenna efficiency could be higher than you would think for some antennas. Is it easier than that with some smarts involved in the pulse - probably yes. Do the smarts raise the hardware cost significantly? - you'd have to build a few and find out. What really drives this or that Loran receiver nuts? I'm quite sure you could work that out with one to play with. Am I gong into the Loran-C jammer business? No, so don't contact me off list to buy one. The point is not *have* I built one, but could one be built easily. Bob On Jul 28, 2013, at 1:29 PM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message dab33aef-98ef-4503-89a7-657f0d25a...@rtty.us, Bob Camp writes: I'm not talking about taking out Loran-C over the entire North Atlantic. The target is a harbor sized area. For that, you certainly do not need a 600' antenna or megawatts of power. No, you need about 600W (continuous) and a loop-antenna about 5m in diameter. Do the math, It's not as easy as you think. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org |
Re: [time-nuts] Rockwell/Conexant Jupiter(?) 10kHz Output Off Frequency
David, If you don't have any luck getting the ZOD1's to work, I have several TU30's if you need one. Please contact me off line. Regards, Doug Connected by DROID on Verizon Wireless -Original message- From: David Smith da...@smithfamily.net.au To: time-nuts@febo.com Sent: Sat, Jul 27, 2013 23:23:40 GMT+00:00 Subject: [time-nuts] Rockwell/Conexant Jupiter(?) 10kHz Output Off Frequency The Jupiter (TU-30) board in my homebrew GPSDO has died. A friend gave me some unmarked Jupiter-like boards with Conexant chips that he had been told were Jupiter compatible. The boards are mounted on an aluminium plate that has a puck-type antenna on it. One of the chips has a sticker with ZOD8 V1.83 printed on it. The boards have the same connections as a Jupiter, and I've been able to connect one to my GPSDO in place of the dead Jupiter. It eventually starts outputting sensible messages with location etc. and the homemade display on the GPSDO shows that everything is supposedly normal. However, the PLL will not lock. Even though there's 10 kHz from the board (which I can only measure to 1 Hz accuracy), the PLL keeps hunting for lock. The 10kHz is in sync with the 1pps also from the board. However, when I compare the 10kHz to 10 MHz from another GPSDO, it doesn't appear synced to GPS - it must only be fractions of a Hz off, though. At the moment, I'm thinking there are 3 possibilities: - I need to send a command to the board to configure the 10kHz/1pps somehow. The Jupiter doco doesn't show any command like that and seems to assume the 10kHz and 1pps are always there. - There are components for the 10kHz/1pps syncing missing. I've already had to add a jumper wire where bits for supplying active antenna power were missing (from factory). - The firmware doesn't support 1pps / 10kHz. Perhaps the boards were meant for navigation only. Does anyone recognise these boards and have experience with extracting 10kHz from them? Regards, David Smith ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
You can't use efficient antenna and 100 kHz in the same sentence. Oh, wait... - Original Message - From: J. Forster j...@quikus.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, July 28, 2013 3:06 PM Subject: Re: [time-nuts] GPS Spoofing The point about the duty cycle being low is correct. And, there are commercial linear power amps, like the used ones made by ENI and others, that can easily put out 1 kW plus narrow pulses. Furthermore, the pulse generator is trivial to make with a Rb, 3 or more Tektronix DD501s, a simple OR gate and a gated oscillator at about 100 kHz. I've cobbled up that setup several times as a LORAN-A simulator. The main difficulty is getting a reasonable match to an efficient antenna at 100 kHz. -John = Hi Since it's a pulse system, and you get to position your pulse for maximum effect, I don't see any reason to generate CW power. Simply mimic the lowest power slave in the chain. There's very little redundancy with Loran, so spoofing one station will mess it up. No need to mask the entire chain. At most you would need to hit two low power slaves. Math wise: Wavelength is 10,000 ft / 3,000M. Throw things off by ~10% of that and you have problems in a harbor. You would need to play a bit to see weather a pulse every so often does the trick or not. Is that 20 db below the slave or not ? You'd have to play with it. It's in that range. A spoof that says they are on the other side of the world isn't going to work. One that says you are on the north side of the channel (when you are on the south side) is what would work. Power within a pulse set at a 5:1 duty cycle. For a 50,000 us GRI you have another 50:1. For longer GRI's you might add another 2:1. Net is a peak to average ratio of 250-1000 to 1. Put another way, a 500W pulse is ~ 1 average. Power at 100 KHz = what's in a fairly cheap switching power supply. Plug it into the wall. A couple hundred watts (or even KW) pulse is cheap. Say you have 120W out of the wall (or a car battery). If the math above is correct and you can run 80% efficiency, that's a pretty powerful pulse. It's probably cheaper to generate something at 50:1 rather than the whole 200:1. A 5KW is a *lot* of RF, even into a simple antenna. Antenna - there's a couple ways to do that. All of them are tradeoffs (size / cost / power). The cheap way is to use a wire that's already there…. Since you don't need to propagate (near field), the antenna efficiency could be higher than you would think for some antennas. Is it easier than that with some smarts involved in the pulse - probably yes. Do the smarts raise the hardware cost significantly? - you'd have to build a few and find out. What really drives this or that Loran receiver nuts? I'm quite sure you could work that out with one to play with. Am I gong into the Loran-C jammer business? No, so don't contact me off list to buy one. The point is not *have* I built one, but could one be built easily. Bob On Jul 28, 2013, at 1:29 PM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message dab33aef-98ef-4503-89a7-657f0d25a...@rtty.us, Bob Camp writes: I'm not talking about taking out Loran-C over the entire North Atlantic. The target is a harbor sized area. For that, you certainly do not need a 600' antenna or megawatts of power. No, you need about 600W (continuous) and a loop-antenna about 5m in diameter. Do the math, It's not as easy as you think. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
Hi So in this case we're talking about horrible to even more horrible in terms of efficiency. I'll freely grant that a 600' tower over a really good ground plane (like say the sea) is going to be way more efficient than anything I'd come up with. The same thing would apply to a matching network made of coils you can stand up inside compared to anything I'd make. Totally off topic - In the lobby of Continental Electronics they used to have this typical transmitter sitting there. You sort of wondered why. After looking at it you figured out the little ant down in the bottom was a person. Yes, the coils and stuff in Omega transmitters were *big*. Bob On Jul 28, 2013, at 4:23 PM, Tom Miller tmil...@skylinenet.net wrote: You can't use efficient antenna and 100 kHz in the same sentence. Oh, wait... - Original Message - From: J. Forster j...@quikus.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, July 28, 2013 3:06 PM Subject: Re: [time-nuts] GPS Spoofing The point about the duty cycle being low is correct. And, there are commercial linear power amps, like the used ones made by ENI and others, that can easily put out 1 kW plus narrow pulses. Furthermore, the pulse generator is trivial to make with a Rb, 3 or more Tektronix DD501s, a simple OR gate and a gated oscillator at about 100 kHz. I've cobbled up that setup several times as a LORAN-A simulator. The main difficulty is getting a reasonable match to an efficient antenna at 100 kHz. -John = Hi Since it's a pulse system, and you get to position your pulse for maximum effect, I don't see any reason to generate CW power. Simply mimic the lowest power slave in the chain. There's very little redundancy with Loran, so spoofing one station will mess it up. No need to mask the entire chain. At most you would need to hit two low power slaves. Math wise: Wavelength is 10,000 ft / 3,000M. Throw things off by ~10% of that and you have problems in a harbor. You would need to play a bit to see weather a pulse every so often does the trick or not. Is that 20 db below the slave or not ? You'd have to play with it. It's in that range. A spoof that says they are on the other side of the world isn't going to work. One that says you are on the north side of the channel (when you are on the south side) is what would work. Power within a pulse set at a 5:1 duty cycle. For a 50,000 us GRI you have another 50:1. For longer GRI's you might add another 2:1. Net is a peak to average ratio of 250-1000 to 1. Put another way, a 500W pulse is ~ 1 average. Power at 100 KHz = what's in a fairly cheap switching power supply. Plug it into the wall. A couple hundred watts (or even KW) pulse is cheap. Say you have 120W out of the wall (or a car battery). If the math above is correct and you can run 80% efficiency, that's a pretty powerful pulse. It's probably cheaper to generate something at 50:1 rather than the whole 200:1. A 5KW is a *lot* of RF, even into a simple antenna. Antenna - there's a couple ways to do that. All of them are tradeoffs (size / cost / power). The cheap way is to use a wire that's already there…. Since you don't need to propagate (near field), the antenna efficiency could be higher than you would think for some antennas. Is it easier than that with some smarts involved in the pulse - probably yes. Do the smarts raise the hardware cost significantly? - you'd have to build a few and find out. What really drives this or that Loran receiver nuts? I'm quite sure you could work that out with one to play with. Am I gong into the Loran-C jammer business? No, so don't contact me off list to buy one. The point is not *have* I built one, but could one be built easily. Bob On Jul 28, 2013, at 1:29 PM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message dab33aef-98ef-4503-89a7-657f0d25a...@rtty.us, Bob Camp writes: I'm not talking about taking out Loran-C over the entire North Atlantic. The target is a harbor sized area. For that, you certainly do not need a 600' antenna or megawatts of power. No, you need about 600W (continuous) and a loop-antenna about 5m in diameter. Do the math, It's not as easy as you think. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
So, given the size of a typical freighter these days, what's so hard about imagining one with enough wire in the air to make that happen for whatever political or commercial reason? Bob From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, July 28, 2013 4:05 PM Subject: Re: [time-nuts] GPS Spoofing Hi So in this case we're talking about horrible to even more horrible in terms of efficiency. I'll freely grant that a 600' tower over a really good ground plane (like say the sea) is going to be way more efficient than anything I'd come up with. The same thing would apply to a matching network made of coils you can stand up inside compared to anything I'd make. Totally off topic - In the lobby of Continental Electronics they used to have this typical transmitter sitting there. You sort of wondered why. After looking at it you figured out the little ant down in the bottom was a person. Yes, the coils and stuff in Omega transmitters were *big*. Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
Hi Small antennas (all antennas at 100 KHz are small) are not a matter of wavelengths of wire in the air. They are a matter of making do with what you have. Efficiency is more a matter of coil loss (or equivalent) than of antenna size. Bob On Jul 28, 2013, at 5:12 PM, Bob Stewart b...@evoria.net wrote: So, given the size of a typical freighter these days, what's so hard about imagining one with enough wire in the air to make that happen for whatever political or commercial reason? Bob From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, July 28, 2013 4:05 PM Subject: Re: [time-nuts] GPS Spoofing Hi So in this case we're talking about horrible to even more horrible in terms of efficiency. I'll freely grant that a 600' tower over a really good ground plane (like say the sea) is going to be way more efficient than anything I'd come up with. The same thing would apply to a matching network made of coils you can stand up inside compared to anything I'd make. Totally off topic - In the lobby of Continental Electronics they used to have this typical transmitter sitting there. You sort of wondered why. After looking at it you figured out the little ant down in the bottom was a person. Yes, the coils and stuff in Omega transmitters were *big*. Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
Hi Actually not the whole story. Propagating (far field) antennas are also a function of producing the polarization you want and a good field remote from the antenna. For instance, you can get a really good field inside a toroid, but it's not a good far filed (or near field) antenna. Bob On Jul 28, 2013, at 5:23 PM, Bob Camp li...@rtty.us wrote: Hi Small antennas (all antennas at 100 KHz are small) are not a matter of wavelengths of wire in the air. They are a matter of making do with what you have. Efficiency is more a matter of coil loss (or equivalent) than of antenna size. Bob On Jul 28, 2013, at 5:12 PM, Bob Stewart b...@evoria.net wrote: So, given the size of a typical freighter these days, what's so hard about imagining one with enough wire in the air to make that happen for whatever political or commercial reason? Bob From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, July 28, 2013 4:05 PM Subject: Re: [time-nuts] GPS Spoofing Hi So in this case we're talking about horrible to even more horrible in terms of efficiency. I'll freely grant that a 600' tower over a really good ground plane (like say the sea) is going to be way more efficient than anything I'd come up with. The same thing would apply to a matching network made of coils you can stand up inside compared to anything I'd make. Totally off topic - In the lobby of Continental Electronics they used to have this typical transmitter sitting there. You sort of wondered why. After looking at it you figured out the little ant down in the bottom was a person. Yes, the coils and stuff in Omega transmitters were *big*. Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
That is why they use litz wire, sometimes three inches in diameter for the coils and for the capacity hat. The ground system includes miles of buried copper. Capacitors are larger than trash cans and gas filled. - Original Message - From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, July 28, 2013 5:23 PM Subject: Re: [time-nuts] GPS Spoofing Hi Small antennas (all antennas at 100 KHz are small) are not a matter of wavelengths of wire in the air. They are a matter of making do with what you have. Efficiency is more a matter of coil loss (or equivalent) than of antenna size. Bob On Jul 28, 2013, at 5:12 PM, Bob Stewart b...@evoria.net wrote: So, given the size of a typical freighter these days, what's so hard about imagining one with enough wire in the air to make that happen for whatever political or commercial reason? Bob From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, July 28, 2013 4:05 PM Subject: Re: [time-nuts] GPS Spoofing Hi So in this case we're talking about horrible to even more horrible in terms of efficiency. I'll freely grant that a 600' tower over a really good ground plane (like say the sea) is going to be way more efficient than anything I'd come up with. The same thing would apply to a matching network made of coils you can stand up inside compared to anything I'd make. Totally off topic - In the lobby of Continental Electronics they used to have this typical transmitter sitting there. You sort of wondered why. After looking at it you figured out the little ant down in the bottom was a person. Yes, the coils and stuff in Omega transmitters were *big*. Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
Hi Part (but not all) of that is related to handling = 400KW pulses. A bit of it also relates to handling lightning hits on the tower. Bob On Jul 28, 2013, at 5:39 PM, Tom Miller tmil...@skylinenet.net wrote: That is why they use litz wire, sometimes three inches in diameter for the coils and for the capacity hat. The ground system includes miles of buried copper. Capacitors are larger than trash cans and gas filled. - Original Message - From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, July 28, 2013 5:23 PM Subject: Re: [time-nuts] GPS Spoofing Hi Small antennas (all antennas at 100 KHz are small) are not a matter of wavelengths of wire in the air. They are a matter of making do with what you have. Efficiency is more a matter of coil loss (or equivalent) than of antenna size. Bob On Jul 28, 2013, at 5:12 PM, Bob Stewart b...@evoria.net wrote: So, given the size of a typical freighter these days, what's so hard about imagining one with enough wire in the air to make that happen for whatever political or commercial reason? Bob From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, July 28, 2013 4:05 PM Subject: Re: [time-nuts] GPS Spoofing Hi So in this case we're talking about horrible to even more horrible in terms of efficiency. I'll freely grant that a 600' tower over a really good ground plane (like say the sea) is going to be way more efficient than anything I'd come up with. The same thing would apply to a matching network made of coils you can stand up inside compared to anything I'd make. Totally off topic - In the lobby of Continental Electronics they used to have this typical transmitter sitting there. You sort of wondered why. After looking at it you figured out the little ant down in the bottom was a person. Yes, the coils and stuff in Omega transmitters were *big*. Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
No better ground plane than salt water... --marki -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Stewart Sent: Monday, 29 July 2013 7:13 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] GPS Spoofing So, given the size of a typical freighter these days, what's so hard about imagining one with enough wire in the air to make that happen for whatever political or commercial reason? Bob From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, July 28, 2013 4:05 PM Subject: Re: [time-nuts] GPS Spoofing Hi So in this case we're talking about horrible to even more horrible in terms of efficiency. I'll freely grant that a 600' tower over a really good ground plane (like say the sea) is going to be way more efficient than anything I'd come up with. The same thing would apply to a matching network made of coils you can stand up inside compared to anything I'd make. Totally off topic - In the lobby of Continental Electronics they used to have this typical transmitter sitting there. You sort of wondered why. After looking at it you figured out the little ant down in the bottom was a person. Yes, the coils and stuff in Omega transmitters were *big*. Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
The Helix coils are 25' high and have a 6' high relay: http://www.haikuvalley.com/History/OMEGA-NAVIGATION-SYSTEM/8839335_kzKJLd#!i=2042047390k=QJbHKzM/ --marki -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Monday, 29 July 2013 7:05 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] GPS Spoofing Hi So in this case we're talking about horrible to even more horrible in terms of efficiency. I'll freely grant that a 600' tower over a really good ground plane (like say the sea) is going to be way more efficient than anything I'd come up with. The same thing would apply to a matching network made of coils you can stand up inside compared to anything I'd make. Totally off topic - In the lobby of Continental Electronics they used to have this typical transmitter sitting there. You sort of wondered why. After looking at it you figured out the little ant down in the bottom was a person. Yes, the coils and stuff in Omega transmitters were *big*. Bob On Jul 28, 2013, at 4:23 PM, Tom Miller tmil...@skylinenet.net wrote: You can't use efficient antenna and 100 kHz in the same sentence. Oh, wait... - Original Message - From: J. Forster j...@quikus.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, July 28, 2013 3:06 PM Subject: Re: [time-nuts] GPS Spoofing The point about the duty cycle being low is correct. And, there are commercial linear power amps, like the used ones made by ENI and others, that can easily put out 1 kW plus narrow pulses. Furthermore, the pulse generator is trivial to make with a Rb, 3 or more Tektronix DD501s, a simple OR gate and a gated oscillator at about 100 kHz. I've cobbled up that setup several times as a LORAN-A simulator. The main difficulty is getting a reasonable match to an efficient antenna at 100 kHz. -John = Hi Since it's a pulse system, and you get to position your pulse for maximum effect, I don't see any reason to generate CW power. Simply mimic the lowest power slave in the chain. There's very little redundancy with Loran, so spoofing one station will mess it up. No need to mask the entire chain. At most you would need to hit two low power slaves. Math wise: Wavelength is 10,000 ft / 3,000M. Throw things off by ~10% of that and you have problems in a harbor. You would need to play a bit to see weather a pulse every so often does the trick or not. Is that 20 db below the slave or not ? You'd have to play with it. It's in that range. A spoof that says they are on the other side of the world isn't going to work. One that says you are on the north side of the channel (when you are on the south side) is what would work. Power within a pulse set at a 5:1 duty cycle. For a 50,000 us GRI you have another 50:1. For longer GRI's you might add another 2:1. Net is a peak to average ratio of 250-1000 to 1. Put another way, a 500W pulse is ~ 1 average. Power at 100 KHz = what's in a fairly cheap switching power supply. Plug it into the wall. A couple hundred watts (or even KW) pulse is cheap. Say you have 120W out of the wall (or a car battery). If the math above is correct and you can run 80% efficiency, that's a pretty powerful pulse. It's probably cheaper to generate something at 50:1 rather than the whole 200:1. A 5KW is a *lot* of RF, even into a simple antenna. Antenna - there's a couple ways to do that. All of them are tradeoffs (size / cost / power). The cheap way is to use a wire that's already there Since you don't need to propagate (near field), the antenna efficiency could be higher than you would think for some antennas. Is it easier than that with some smarts involved in the pulse - probably yes. Do the smarts raise the hardware cost significantly? - you'd have to build a few and find out. What really drives this or that Loran receiver nuts? I'm quite sure you could work that out with one to play with. Am I gong into the Loran-C jammer business? No, so don't contact me off list to buy one. The point is not *have* I built one, but could one be built easily. Bob On Jul 28, 2013, at 1:29 PM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message dab33aef-98ef-4503-89a7-657f0d25a...@rtty.us, Bob Camp writes: I'm not talking about taking out Loran-C over the entire North Atlantic. The target is a harbor sized area. For that, you certainly do not need a 600' antenna or megawatts of power. No, you need about 600W (continuous) and a loop-antenna about 5m in diameter. Do the math, It's not as easy as you think. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by
Re: [time-nuts] GPS Spoofing
I'm not so convinced about this: OMEGA was the primary means of radio navigation, world wide, from 1976 to 1997. . There was LORAN-C, after all. And Omega was a CW, phase difference system, LORAN a pulse system. AFAIK, Omega never really made it into the uP age; LORAN certainly did. -John === The Helix coils are 25' high and have a 6' high relay: http://www.haikuvalley.com/History/OMEGA-NAVIGATION-SYSTEM/8839335_kzKJLd#!i=2042047390k=QJbHKzM/ --marki -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Monday, 29 July 2013 7:05 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] GPS Spoofing Hi So in this case we're talking about horrible to even more horrible in terms of efficiency. I'll freely grant that a 600' tower over a really good ground plane (like say the sea) is going to be way more efficient than anything I'd come up with. The same thing would apply to a matching network made of coils you can stand up inside compared to anything I'd make. Totally off topic - In the lobby of Continental Electronics they used to have this typical transmitter sitting there. You sort of wondered why. After looking at it you figured out the little ant down in the bottom was a person. Yes, the coils and stuff in Omega transmitters were *big*. Bob On Jul 28, 2013, at 4:23 PM, Tom Miller tmil...@skylinenet.net wrote: You can't use efficient antenna and 100 kHz in the same sentence. Oh, wait... - Original Message - From: J. Forster j...@quikus.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, July 28, 2013 3:06 PM Subject: Re: [time-nuts] GPS Spoofing The point about the duty cycle being low is correct. And, there are commercial linear power amps, like the used ones made by ENI and others, that can easily put out 1 kW plus narrow pulses. Furthermore, the pulse generator is trivial to make with a Rb, 3 or more Tektronix DD501s, a simple OR gate and a gated oscillator at about 100 kHz. I've cobbled up that setup several times as a LORAN-A simulator. The main difficulty is getting a reasonable match to an efficient antenna at 100 kHz. -John = Hi Since it's a pulse system, and you get to position your pulse for maximum effect, I don't see any reason to generate CW power. Simply mimic the lowest power slave in the chain. There's very little redundancy with Loran, so spoofing one station will mess it up. No need to mask the entire chain. At most you would need to hit two low power slaves. Math wise: Wavelength is 10,000 ft / 3,000M. Throw things off by ~10% of that and you have problems in a harbor. You would need to play a bit to see weather a pulse every so often does the trick or not. Is that 20 db below the slave or not ? You'd have to play with it. It's in that range. A spoof that says they are on the other side of the world isn't going to work. One that says you are on the north side of the channel (when you are on the south side) is what would work. Power within a pulse set at a 5:1 duty cycle. For a 50,000 us GRI you have another 50:1. For longer GRI's you might add another 2:1. Net is a peak to average ratio of 250-1000 to 1. Put another way, a 500W pulse is ~ 1 average. Power at 100 KHz = what's in a fairly cheap switching power supply. Plug it into the wall. A couple hundred watts (or even KW) pulse is cheap. Say you have 120W out of the wall (or a car battery). If the math above is correct and you can run 80% efficiency, that's a pretty powerful pulse. It's probably cheaper to generate something at 50:1 rather than the whole 200:1. A 5KW is a *lot* of RF, even into a simple antenna. Antenna - there's a couple ways to do that. All of them are tradeoffs (size / cost / power). The cheap way is to use a wire that's already there Since you don't need to propagate (near field), the antenna efficiency could be higher than you would think for some antennas. Is it easier than that with some smarts involved in the pulse - probably yes. Do the smarts raise the hardware cost significantly? - you'd have to build a few and find out. What really drives this or that Loran receiver nuts? I'm quite sure you could work that out with one to play with. Am I gong into the Loran-C jammer business? No, so don't contact me off list to buy one. The point is not *have* I built one, but could one be built easily. Bob On Jul 28, 2013, at 1:29 PM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message dab33aef-98ef-4503-89a7-657f0d25a...@rtty.us, Bob Camp writes: I'm not talking about taking out Loran-C over the entire North Atlantic. The target is a harbor sized area. For that, you certainly do not need a 600' antenna or megawatts of power. No, you need about 600W (continuous) and a loop-antenna about 5m in diameter. Do
Re: [time-nuts] More pictures of the mystery Collins Ru
If they needed an airborne rubidium standard it must have been for digitally scrambled communications. That has been around since the 60s. Regards. Max. K 4 O DS. Email: m...@maxsmusicplace.com Transistor site http://www.funwithtransistors.net Vacuum tube site: http://www.funwithtubes.net Woodworking site http://www.angelfire.com/electronic/funwithtubes/Woodworking/wwindex.html Music site: http://www.maxsmusicplace.com To subscribe to the fun with transistors group send an email to. funwithtransistors-subscr...@yahoogroups.com To subscribe to the fun with tubes group send an email to, funwithtubes-subscr...@yahoogroups.com To subscribe to the fun with wood group send a blank email to funwithwood-subscr...@yahoogroups.com - Original Message - From: Tim Shoppa tsho...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, July 28, 2013 9:25 AM Subject: Re: [time-nuts] More pictures of the mystery Collins Ru Googling a little bit, I find several references to a Collins rubidium package AFS-81 for airborne survivable VLF communications in the 60's (predating this unit by maybe two decades). Still trying to wrap my head around why that would need rubidium unless it was an airborne WWVB replacement or something. Googling also turned up the modern Rockwell-Collins 617A-1 VLF amp which seems to be a dinky solid state unit that is rated at a third of a megawatt. Still having a hard time wrapping my mind around that! Maybe I'm off by 2 or 3 orders of magnitude or the picture is just the control head, the real amplifier is the size of a building. A third of a megawatt must be the size of the fixed transmitters used for VLF submarine communications. Tim N3QE On Sun, Jul 28, 2013 at 9:40 AM, Pete Lancashire p...@petelancashire.comwrote: maybe I should read things more often .. yikes I need a vacation On Sun, Jul 28, 2013 at 7:01 AM, George Dubovsky n4ua...@gmail.com wrote: Well, the outside label does claim it was made by GENRAD... ;-) 73, geo - n4ua On Sat, Jul 27, 2013 at 9:24 PM, Pete Lancashire p...@petelancashire.com wrote: https://plus.google.com/u/0/photos/111617808980322733757/albums/5890266601277045697 The board with the edge connector was inside the same bag the connector was in, the bag was taped to the unit. I pulled the ends off first, but was immediately stopped with foam, it is glued in place. Then when I finally got the lid with all the screws off, all there is, is one board covered in potting compound. The compound breaks away pretty easily. One can see where a couple parts were replaced and there soft RTV was used. There are two precision resistors in that area. The biggest surprise is the General Radio logo on the board ! goo.gl/1XGG2F ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
Hi Omega was world wide, Loran was not. Anything that operated over *long* distances (tankers, airplanes) was Omega. They pulled Omega gear off of the planes and replaced it with GPS. I suspect they did the same thing on the big tankers. Bob On Jul 28, 2013, at 6:24 PM, J. Forster j...@quikus.com wrote: I'm not so convinced about this: OMEGA was the primary means of radio navigation, world wide, from 1976 to 1997. . There was LORAN-C, after all. And Omega was a CW, phase difference system, LORAN a pulse system. AFAIK, Omega never really made it into the uP age; LORAN certainly did. -John === The Helix coils are 25' high and have a 6' high relay: http://www.haikuvalley.com/History/OMEGA-NAVIGATION-SYSTEM/8839335_kzKJLd#!i=2042047390k=QJbHKzM/ --marki -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Monday, 29 July 2013 7:05 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] GPS Spoofing Hi So in this case we're talking about horrible to even more horrible in terms of efficiency. I'll freely grant that a 600' tower over a really good ground plane (like say the sea) is going to be way more efficient than anything I'd come up with. The same thing would apply to a matching network made of coils you can stand up inside compared to anything I'd make. Totally off topic - In the lobby of Continental Electronics they used to have this typical transmitter sitting there. You sort of wondered why. After looking at it you figured out the little ant down in the bottom was a person. Yes, the coils and stuff in Omega transmitters were *big*. Bob On Jul 28, 2013, at 4:23 PM, Tom Miller tmil...@skylinenet.net wrote: You can't use efficient antenna and 100 kHz in the same sentence. Oh, wait... - Original Message - From: J. Forster j...@quikus.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, July 28, 2013 3:06 PM Subject: Re: [time-nuts] GPS Spoofing The point about the duty cycle being low is correct. And, there are commercial linear power amps, like the used ones made by ENI and others, that can easily put out 1 kW plus narrow pulses. Furthermore, the pulse generator is trivial to make with a Rb, 3 or more Tektronix DD501s, a simple OR gate and a gated oscillator at about 100 kHz. I've cobbled up that setup several times as a LORAN-A simulator. The main difficulty is getting a reasonable match to an efficient antenna at 100 kHz. -John = Hi Since it's a pulse system, and you get to position your pulse for maximum effect, I don't see any reason to generate CW power. Simply mimic the lowest power slave in the chain. There's very little redundancy with Loran, so spoofing one station will mess it up. No need to mask the entire chain. At most you would need to hit two low power slaves. Math wise: Wavelength is 10,000 ft / 3,000M. Throw things off by ~10% of that and you have problems in a harbor. You would need to play a bit to see weather a pulse every so often does the trick or not. Is that 20 db below the slave or not ? You'd have to play with it. It's in that range. A spoof that says they are on the other side of the world isn't going to work. One that says you are on the north side of the channel (when you are on the south side) is what would work. Power within a pulse set at a 5:1 duty cycle. For a 50,000 us GRI you have another 50:1. For longer GRI's you might add another 2:1. Net is a peak to average ratio of 250-1000 to 1. Put another way, a 500W pulse is ~ 1 average. Power at 100 KHz = what's in a fairly cheap switching power supply. Plug it into the wall. A couple hundred watts (or even KW) pulse is cheap. Say you have 120W out of the wall (or a car battery). If the math above is correct and you can run 80% efficiency, that's a pretty powerful pulse. It's probably cheaper to generate something at 50:1 rather than the whole 200:1. A 5KW is a *lot* of RF, even into a simple antenna. Antenna - there's a couple ways to do that. All of them are tradeoffs (size / cost / power). The cheap way is to use a wire that's already there Since you don't need to propagate (near field), the antenna efficiency could be higher than you would think for some antennas. Is it easier than that with some smarts involved in the pulse - probably yes. Do the smarts raise the hardware cost significantly? - you'd have to build a few and find out. What really drives this or that Loran receiver nuts? I'm quite sure you could work that out with one to play with. Am I gong into the Loran-C jammer business? No, so don't contact me off list to buy one. The point is not *have* I built one, but could one be built easily. Bob On Jul 28, 2013, at 1:29 PM, Poul-Henning Kamp
Re: [time-nuts] More pictures of the mystery Collins Ru
A reference to GR and Rubidium http://www.ieee-uffc.org/frequency-control/memoria-stratemeyer.asp Did the GR 1115A, Sounds like an interesting person. On Sat, Jul 27, 2013 at 6:24 PM, Pete Lancashire p...@petelancashire.comwrote: https://plus.google.com/u/0/photos/111617808980322733757/albums/5890266601277045697 The board with the edge connector was inside the same bag the connector was in, the bag was taped to the unit. I pulled the ends off first, but was immediately stopped with foam, it is glued in place. Then when I finally got the lid with all the screws off, all there is, is one board covered in potting compound. The compound breaks away pretty easily. One can see where a couple parts were replaced and there soft RTV was used. There are two precision resistors in that area. The biggest surprise is the General Radio logo on the board ! goo.gl/1XGG2F ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] More pictures of the mystery Collins Ru
Hi: The military UHF voice radio scrambling depends on accurate time, hence the Have Quick (and follow on programs) time transfer standard. Rb standards were used to maintain that time in the early days. The O-1814 Rb standard was used to keep time on the ground accurate so that when a plane flew in from far away the crypto would be in sync. http://www.prc68.com/I/O1814.shtml PS has anyone done any PIC Have Quick stuff? Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html Brooke Clarke wrote: Hi: I think (3). See: http://en.wikipedia.org/wiki/TACAMO http://en.wikipedia.org/wiki/Ground_Wave_Emergency_Network - some converted to DGPS Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html Robert Atkinson wrote: Hi Tim, Three possible reasons for needing a Rb standard, 1/ Coherent detection with a local clock 2/ Hyperbolic navigation (local reference improves the fix and holdover) 3/ Secure communications. Robert G8RPI From: Tim Shoppa tsho...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, 28 July 2013, 15:25 Subject: Re: [time-nuts] More pictures of the mystery Collins Ru Googling a little bit, I find several references to a Collins rubidium package AFS-81 for airborne survivable VLF communications in the 60's (predating this unit by maybe two decades). Still trying to wrap my head around why that would need rubidium unless it was an airborne WWVB replacement or something. Googling also turned up the modern Rockwell-Collins 617A-1 VLF amp which seems to be a dinky solid state unit that is rated at a third of a megawatt. Still having a hard time wrapping my mind around that! Maybe I'm off by 2 or 3 orders of magnitude or the picture is just the control head, the real amplifier is the size of a building. A third of a megawatt must be the size of the fixed transmitters used for VLF submarine communications. Tim N3QE On Sun, Jul 28, 2013 at 9:40 AM, Pete Lancashire p...@petelancashire.comwrote: maybe I should read things more often .. yikes I need a vacation On Sun, Jul 28, 2013 at 7:01 AM, George Dubovsky n4ua...@gmail.com wrote: Well, the outside label does claim it was made by GENRAD... ;-) 73, geo - n4ua On Sat, Jul 27, 2013 at 9:24 PM, Pete Lancashire p...@petelancashire.com wrote: https://plus.google.com/u/0/photos/111617808980322733757/albums/5890266601277045697 The board with the edge connector was inside the same bag the connector was in, the bag was taped to the unit. I pulled the ends off first, but was immediately stopped with foam, it is glued in place. Then when I finally got the lid with all the screws off, all there is, is one board covered in potting compound. The compound breaks away pretty easily. One can see where a couple parts were replaced and there soft RTV was used. There are two precision resistors in that area. The biggest surprise is the General Radio logo on the board ! goo.gl/1XGG2F ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] More pictures of the mystery Collins Ru
Hi …. There was a suitcase Rb that was used to sync up Have Quick's on the ground. It was a Magnavox product rather than Collins. The idea was to get the radios netted up without *anything* going over the air. Since the radios used TCXO's, sync was fairly loose. I suspect that tightened up as they went through the various versions ... Bob On Jul 28, 2013, at 6:58 PM, Brooke Clarke bro...@pacific.net wrote: Hi: The military UHF voice radio scrambling depends on accurate time, hence the Have Quick (and follow on programs) time transfer standard. Rb standards were used to maintain that time in the early days. The O-1814 Rb standard was used to keep time on the ground accurate so that when a plane flew in from far away the crypto would be in sync. http://www.prc68.com/I/O1814.shtml PS has anyone done any PIC Have Quick stuff? Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html Brooke Clarke wrote: Hi: I think (3). See: http://en.wikipedia.org/wiki/TACAMO http://en.wikipedia.org/wiki/Ground_Wave_Emergency_Network - some converted to DGPS Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html Robert Atkinson wrote: Hi Tim, Three possible reasons for needing a Rb standard, 1/ Coherent detection with a local clock 2/ Hyperbolic navigation (local reference improves the fix and holdover) 3/ Secure communications. Robert G8RPI From: Tim Shoppa tsho...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, 28 July 2013, 15:25 Subject: Re: [time-nuts] More pictures of the mystery Collins Ru Googling a little bit, I find several references to a Collins rubidium package AFS-81 for airborne survivable VLF communications in the 60's (predating this unit by maybe two decades). Still trying to wrap my head around why that would need rubidium unless it was an airborne WWVB replacement or something. Googling also turned up the modern Rockwell-Collins 617A-1 VLF amp which seems to be a dinky solid state unit that is rated at a third of a megawatt. Still having a hard time wrapping my mind around that! Maybe I'm off by 2 or 3 orders of magnitude or the picture is just the control head, the real amplifier is the size of a building. A third of a megawatt must be the size of the fixed transmitters used for VLF submarine communications. Tim N3QE On Sun, Jul 28, 2013 at 9:40 AM, Pete Lancashire p...@petelancashire.comwrote: maybe I should read things more often .. yikes I need a vacation On Sun, Jul 28, 2013 at 7:01 AM, George Dubovsky n4ua...@gmail.com wrote: Well, the outside label does claim it was made by GENRAD... ;-) 73, geo - n4ua On Sat, Jul 27, 2013 at 9:24 PM, Pete Lancashire p...@petelancashire.com wrote: https://plus.google.com/u/0/photos/111617808980322733757/albums/5890266601277045697 The board with the edge connector was inside the same bag the connector was in, the bag was taped to the unit. I pulled the ends off first, but was immediately stopped with foam, it is glued in place. Then when I finally got the lid with all the screws off, all there is, is one board covered in potting compound. The compound breaks away pretty easily. One can see where a couple parts were replaced and there soft RTV was used. There are two precision resistors in that area. The biggest surprise is the General Radio logo on the board ! goo.gl/1XGG2F ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
Re: [time-nuts] More pictures of the mystery Collins Ru
On Sun, Jul 28, 2013 at 07:54:47PM -0400, Bob Camp wrote: Hi …. There was a suitcase Rb that was used to sync up Have Quick's on the ground. It was a Magnavox product rather than Collins. The idea was to get the radios netted up without *anything* going over the air. Since the radios used TCXO's, sync was fairly loose. I suspect that tightened up as they went through the various versions ... Bob On Jul 28, 2013, at 6:58 PM, Brooke Clarke bro...@pacific.net wrote: Hi: The military UHF voice radio scrambling depends on accurate time, hence the Have Quick (and follow on programs) time transfer standard. Rb standards were used to maintain that time in the early days. A minor quibble - HAVE QUICK is really not meant as a voice scrambling system but an anti-jam ECCM technology. If you hop around every so often to a frequency that is unpredicatable (chosen by a cryptographic random sequence) your opponent has to find and follow you to jam you and do this fast enough to actually cause you problems. Otherwise he is stuck with barrage jamming the entire band. Hopping like this does require synchronized clocks... thus the Rb... in order to hop at the right time to the right place. There are several current and historic voice encryption systems that provide strong voice security without hopping - lots of crypto technology for that. But HAVE QUICK is often used with plain ole in the clear AM voice and that voice can be reconstructed by having receivers for each of the hop frequencies that vote on the strongest signal (or some virtual equivalent of all of this done with FFTs and the like). Most cryptosystems do not depend on precise time of day, though some antique ones did... -- Dave Emery N1PRE/AE, d...@dieconsulting.com DIE Consulting, Weston, Mass 02493 An empty zombie mind with a forlorn barely readable weatherbeaten 'For Rent' sign still vainly flapping outside on the weed encrusted pole - in celebration of what could have been, but wasn't and is not to be now either. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
Interesting comments about navigation of ships and GPS spoofing potential. As a recreational offshore captain/navigator, over the years I've used a few generations each of RDF, Loran, GPS, and radar. My most recent extended nautical travels have been on 100 passenger exploration ships, 300' +/- with open bridge policies, where I spent a fair amount of time with the crews in different oceans of the world. Disasters are most often caused by stupid, drunk, or asleep captains/crews, not by the electronics. Further, the SOLAS regs for all commercial ships require a lot of redundancy, a minimum two each radars, AIS, and GPS and more are usually on the bridge. There may be a molasses tanker out there with only a compass, but it is illegal and isn't going into any managed port in the world. In any close to obstruction/land situation, radar, visual fixes, and soundings are the primary redundant navigation tools. GPS is mostly ignored as a position plot tool, except for anchor watch, once anchored.Electronic charts, often integrated with the radar are one plot tool and paper charts with detailed course plots, soundings, and visual fixes are another. Offshore navigation is a different ball game, mostly radar and visual watches and hourly GPS position plots by the navigator in the log and on the paper voyage chart. AIS is required on all ships and that makes the radar returns much more useful. Current radars, with integrated AIS, all the plotting tools for traffic, closest approach plots, etc. get constant attention. As mentioned, underway, a GPS often updates the autopilot course setting, usually track mode to avoid current drift. A magnetic/gyro/inertial compass system corrects the autopilot for real time rudder control. Navigation tool redundancy and crew alertness keeps ships from going where the ducks are walking. Charts are frequently suspect. On one cruise, we were in an estuary in remote NW Australia, nothing but blue water on the chart, no soundings, no depth contours. I asked the captain about this, a bit surprising to me to be there in a large ship. He had been there before, saved the prior successful GPS plot, and that in combination with go slow, forward looking sonar, soundings, and a mud bottom worked for him. Charts with notations soundings from 1894 means be extra careful. My handheld GPS didn't agree with charted positions of several reefs and islands by tenths of NM or more even after careful cross checking of chart and GPS reference datums. My old lorans sometimes showed me a few hundred yards on the beach when comfortably at anchor. In coastal waters we learned that Loran C positions were fairly repeatable and somewhat inaccurate. Offshore, I'd check now and then any electronic position with celestial, the ultimate backup/crosscheck and just for practice. (pretty hard to spoof, also). One navigator showed me a factor that might have contributed to the Concordia sinking in addition to stupid. The web update to the required electronic chart (all charts paper and electronic are updated monthly on commercial vessels) moved the obstruction marker buoy symbol and depth number images on top of each other, so one had to look very closely to see the depth number, which obviously was not enough for the Concordia. So, stupid crew plus a tiny slip of a cartographers mouse sank it. I would also note that many recreational boaters, trust GPS to take them in pea soup fog to the dock waypoint or through the tight pass. YMMV. Grant KZ1W ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Spoofing
The idea behind GPS spoofing is that one or several surface antennas and sources could be set up in such a way that they would produce believable position data that would take a vessel off course. The problem with this concept is that the person in charge of the GPS spoofing hardware has to know exactly where the vessel is at all times to start with and other vessels some distance away, and not very far from the target vessel would get contradicting signals from the virtual satellites. Software could be used to detect changes in position data that is inconsistent with present course and recent data. And in most cases there would be a period of very inconsistent signals from satellites and more obvious, signal strengths. Another way to limit spoofing is to use directional antennas that prevent reception from near horizon signals. Or detect low angle signals and sound the alarm or implement a means of ignoring those sources. The problem very high tech systems are often defeated by low tech solutions. Successful GPS spoofing would be very high tech. Many high tech systems that the government had developed in the past have been defeated by low tech methods. An example is the microwave system that is intended to turn back rioters by inducing burning pain. It was defeated by using thick wooden shields which absorbed the RF energy. Human resourcefulness and determination often defeats technology in low tech ways. And the more complex a system is the easier it is to defeat. “The more they overtake the plumbing the easier it is to stop up the drain.” Most discussions have been about wireless spoofing. However, the most reliable way to do it would be an “inside job” where a device would be put on board and patched in the antenna lead. The correct GPS data would be received by the device and then it would produce a virtual constellation of satellites that would direct the vessel off course. However, the programmer would have to know the course that the pilot intended to take in the first place if his goal is to take the vessel to a different destination. 73 Bill wa4lav ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
