Re: [time-nuts] Thunderbolt Height Error
Hi Demian, Did you make sure the altitude/height is using the same reference? The GPS system measures relative an ellipsoid approximation of the earth. Sometimes this is used in receiver output messages. To translate this to Mean Sea Level/geoid you need to apply a location dependant correction. The GPS receivers will happily emit both height measures in different messages, its important to understand which is used in the specific messages you are comparing. Have it better explained in the below url: http://www.esri.com/news/arcuser/0703/geoid1of3.html Also not that height accuracy of GNSS is worse than its horizontal accuracy by almost a factor of 2. -- Björn I have 2 GPSDO's. A Thunderbolt and an Arbiter 1083A. The Arbiter is old but it works fine (and has a Wenzel 5 MHz streamline oscillator in it). It has the 1995 firmware issue, and I could get new firmware for it ($$) but I'm not using it as a clock, just a frequency source. I just moved and have re-setup both. They share an antenna. I got both to do a self survey. The Arbiter was really close to what Google maps indicate is my location. The Thunderbolt was about the same except it has me underground. The arbiter has the height as +30M. The Thunderbolt as -6M. What setting do I have wrong in the Thunderbolt? Would it affect the operation as a frequency standard in any way? Demian Martin San Leandro, CA 94577 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Thunderbolt Height Error
Le 18 mai 2015 à 08:34, Demian Martin demianm@gmail.com a écrit : I have 2 GPSDO's. A Thunderbolt and an Arbiter 1083A. The Arbiter is old but it works fine (and has a Wenzel 5 MHz streamline oscillator in it). It has the 1995 firmware issue, and I could get new firmware for it ($$) but I'm not using it as a clock, just a frequency source. I just moved and have re-setup both. They share an antenna. I got both to do a self survey. The Arbiter was really close to what Google maps indicate is my location. The Thunderbolt was about the same except it has me underground. The arbiter has the height as +30M. The Thunderbolt as -6M. Check to see if they are both using the same DATUM. Google maps appears to use WGS-84. Maybe your T-Bolt restarted with something else though it’s default config is WGS-84. I don’t see a command line option to set datum with Lady Heather. If you have a serial link you can set/report with 0x8E,0x8F packets according to the manual What setting do I have wrong in the Thunderbolt? Would it affect the operation as a frequency standard in any way? I don’t think so. The receiver should take the configured datum model into account. Be an interesting experiment to check that. Demian Martin San Leandro, CA 94577 ___ 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. Ceux qui sont prêts à abandonner une liberté essentielle pour obtenir une petite et provisoire sécurité, ne méritent ni liberté ni sécurité. Benjimin Franklin ___ 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] Thunderbolt Height Error
I have 2 GPSDO's. A Thunderbolt and an Arbiter 1083A. The Arbiter is old but it works fine (and has a Wenzel 5 MHz streamline oscillator in it). It has the 1995 firmware issue, and I could get new firmware for it ($$) but I'm not using it as a clock, just a frequency source. I just moved and have re-setup both. They share an antenna. I got both to do a self survey. The Arbiter was really close to what Google maps indicate is my location. The Thunderbolt was about the same except it has me underground. The arbiter has the height as +30M. The Thunderbolt as -6M. What setting do I have wrong in the Thunderbolt? Would it affect the operation as a frequency standard in any way? Demian Martin San Leandro, CA 94577 ___ 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] iGPS?
Hi “Orders of magnitude” more accurate … Right now, you can get around ~1 M in most areas. One order of magnitude would be 10 cm. More than one order of magnitude would be 10 mm. To me “orders” implies more than two, so that would be 1 mm. I guess everybody can toss out all their multi band GPS gear, there’s no need for it anymore. No need to put up all those expensive block III GPS sat’s either :) hm……I do believe the marketing boys have been playing with the numbers. You would have to start from a 50 M error to get them to make much sense based on what they are doing. === If you dig a bit more, Apple bought Coherent Navigation almost a half year ago. The main purpose appears to be merging their mapping software into Apple’s ill-fated maps program. Given that Iridium is a “pay’ service (as in $) you probably will not see it in run of the mill cell phones very soon …. Bob On May 17, 2015, at 7:07 PM, Chris Albertson albertson.ch...@gmail.com wrote: Anyone know anything about iGPS? Apparently the Iridium low orbit communications sats are now modified via software update to send signals that when combined with GPS allow for a receiver that is MUCH more precise and harder to jam and can work in urban areas better. Apple just bought a company that is building iGPS receivers. Looks like something that they might want to put inside a cell phone but when you have an orders of magnitude important in position you'd expect better timing too, or so I would think. Seems like a very smart idea if all that was required was a software upload to existing spacecraft. From what I read this is real, not a proposal another are real receivers being tested. -- Chris Albertson Redondo Beach, California ___ 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] Divider circuit for Rubidium Standard
Hi Bob: i assume when you are referring to the comparator you are referencing the ADCMP600 or MAX999 that is used to clock shape the input for the logic dividers etc and the 74AC541 bus drivers. Could one modify the circuit to use a low noise LTC6957 to clock shape and then divide down using the existing circuitry. I would assume this would offer a greater improvement in phase noise? Cheers -=Bryan=- From: kb...@n1k.org Date: Fri, 8 May 2015 17:19:59 -0400 To: time-nuts@febo.com Subject: Re: [time-nuts] Divider circuit for Rubidium Standard Hi I guess the simple answer is “when you measure them that’s the result”. The slightly more complex answer is “fast silicon CMOS is indeed good, other types may require further analysis”. In general the faster stuff is better than the slower CMOS. Deeper into it you get to the fact that the gate is optimized for one input swing range, speed and consistent (short) delay. The amount of time that anything in a CMOS gate spends in-between “on” and “off” if very short. If you look at the time it’s hooked to a rail as noiseless (= quiet supplies), then the time noise can get into the output is quite short. Short time = little noise. You could go further with fancy tools. Bob On May 7, 2015, at 11:09 AM, Attila Kinali att...@kinali.ch wrote: On Wed, 06 May 2015 18:09:03 -0700 Richard (Rick) Karlquist rich...@karlquist.com wrote: A standard input on a frequency counter is not a very demanding thing in the hierarchy of TimeNut signals. You can drive any of them with some pretty simple logic gate based circuits. No need to spend a lot of money. Logic gate, yes. Comparator, no. This reminds me a lot of a similar discussion a couple of weeks ago. (where the issue boiled down to noise bandwidth) What is the problem with a comparator vs a logic gate? What makes the logic gate supperior? Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ 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] iGPS?
On 2015-05-17 17:07, Chris Albertson wrote: Anyone know anything about iGPS? Apparently the Iridium low orbit communications sats are now modified via software update to send signals that when combined with GPS allow for a receiver that is MUCH more precise and harder to jam and can work in urban areas better. Apple just bought a company that is building iGPS receivers. Looks like something that they might want to put inside a cell phone but when you have an orders of magnitude important in position you'd expect better timing too, or so I would think. Seems like a very smart idea if all that was required was a software upload to existing spacecraft. From what I read this is real, not a proposal another are real receivers being tested. Background: http://www.redorbit.com/news/business/1719742/iridiumboeing_team_completes_high_integrity_gps_program_milestones News: http://www.iphoneincanada.ca/news/apple-has-reportedly-acquired-gps-firm-coherent-navigation -- Take care. Thanks, Brian Inglis ___ 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] iGPS?
Hi Bob: In the link in the message from Brian it explains that iGPS is for military users of the Iridium system. The key feature is to allow a moving vehicle to lock on the GPS signal while being jammed. They do that and also get a more accurate fix by using signals from the Iridium satellites. I see a potential problem in that the Iridium signals are close in frequency to GPS and a broad band jammer might cause a problem for both of them. Mail_Attachment -- Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html http://www.prc68.com/I/DietNutrition.html Bob Camp wrote: Hi “Orders of magnitude” more accurate … Right now, you can get around ~1 M in most areas. One order of magnitude would be 10 cm. More than one order of magnitude would be 10 mm. To me “orders” implies more than two, so that would be 1 mm. I guess everybody can toss out all their multi band GPS gear, there’s no need for it anymore. No need to put up all those expensive block III GPS sat’s either :) hm……I do believe the marketing boys have been playing with the numbers. You would have to start from a 50 M error to get them to make much sense based on what they are doing. === If you dig a bit more, Apple bought Coherent Navigation almost a half year ago. The main purpose appears to be merging their mapping software into Apple’s ill-fated maps program. Given that Iridium is a “pay’ service (as in $) you probably will not see it in run of the mill cell phones very soon …. Bob On May 17, 2015, at 7:07 PM, Chris Albertson albertson.ch...@gmail.com wrote: Anyone know anything about iGPS? Apparently the Iridium low orbit communications sats are now modified via software update to send signals that when combined with GPS allow for a receiver that is MUCH more precise and harder to jam and can work in urban areas better. Apple just bought a company that is building iGPS receivers. Looks like something that they might want to put inside a cell phone but when you have an orders of magnitude important in position you'd expect better timing too, or so I would think. Seems like a very smart idea if all that was required was a software upload to existing spacecraft. From what I read this is real, not a proposal another are real receivers being tested. -- Chris Albertson Redondo Beach, California ___ 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] iGPS?
On 5/18/15 11:06 AM, Brooke Clarke wrote: Hi Bob: In the link in the message from Brian it explains that iGPS is for military users of the Iridium system. The key feature is to allow a moving vehicle to lock on the GPS signal while being jammed. They do that and also get a more accurate fix by using signals from the Iridium satellites. I see a potential problem in that the Iridium signals are close in frequency to GPS and a broad band jammer might cause a problem for both of them. Any system that is concerned about jamming is probably going to be immune to broadband jamming: after all, GPS signals are already below the noise floor. Broadband jamming is a pretty ineffective use of RF power. ___ 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] iGPS?
Yes GPS can do better than 50M but we are talking about a single fix from a cell phone in a moving car not a survey receiver. . The displayed location is better because the phone applies a filter to the location data. Some thing like a Kalman filter. I doubt the iPhone can get within 10M from a moving car. As for Iridium being an expensive for pay service. But that is because most users SEND data. This new service is broadcast and costs do not depend on the number of users. Apple has sold 130,000,000 phones already just in this half of 2015. A one time payment of about $1 per phone might cover the costs. hm……I do believe the marketing boys have been playing with the numbers. You would have to start from a 50 M error to get them to make much sense based on what they are doing. -- Chris Albertson Redondo Beach, California ___ 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] iGPS?
On 5/18/15 7:59 PM, Chris Albertson wrote: Yes GPS can do better than 50M but we are talking about a single fix from a cell phone in a moving car not a survey receiver. . The displayed location is better because the phone applies a filter to the location data. Some thing like a Kalman filter. I doubt the iPhone can get within 10M from a moving car. As for Iridium being an expensive for pay service. But that is because most users SEND data. This new service is broadcast and costs do not depend on the number of users. Apple has sold 130,000,000 phones already just in this half of 2015. A one time payment of about $1 per phone might cover the costs. Why iridium? Why not Sirius or XM or DBS. Unless you want something world wide, as opposed to populated areas served by broadcast radio and TV Heck, you could probably buy transponder time on a C-band satellite and radiate a GPS assist signal (that's what WAAS is, after all) hm……I do believe the marketing boys have been playing with the numbers. You would have to start from a 50 M error to get them to make much sense based on what they are doing. ___ 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] Divider circuit for Rubidium Standard
Hi The simple answer is that pumping the sine wave into a biased logic gate works down to at least the 2x10^-13 (at 1 second tau) level. Why spend more than 10 cents when you don’t have to ? Bob On May 18, 2015, at 6:19 AM, Bryan _ bpl...@outlook.com wrote: Hi Bob: i assume when you are referring to the comparator you are referencing the ADCMP600 or MAX999 that is used to clock shape the input for the logic dividers etc and the 74AC541 bus drivers. Could one modify the circuit to use a low noise LTC6957 to clock shape and then divide down using the existing circuitry. I would assume this would offer a greater improvement in phase noise? Cheers -=Bryan=- From: kb...@n1k.org Date: Fri, 8 May 2015 17:19:59 -0400 To: time-nuts@febo.com Subject: Re: [time-nuts] Divider circuit for Rubidium Standard Hi I guess the simple answer is “when you measure them that’s the result”. The slightly more complex answer is “fast silicon CMOS is indeed good, other types may require further analysis”. In general the faster stuff is better than the slower CMOS. Deeper into it you get to the fact that the gate is optimized for one input swing range, speed and consistent (short) delay. The amount of time that anything in a CMOS gate spends in-between “on” and “off” if very short. If you look at the time it’s hooked to a rail as noiseless (= quiet supplies), then the time noise can get into the output is quite short. Short time = little noise. You could go further with fancy tools. Bob On May 7, 2015, at 11:09 AM, Attila Kinali att...@kinali.ch wrote: On Wed, 06 May 2015 18:09:03 -0700 Richard (Rick) Karlquist rich...@karlquist.com wrote: A standard input on a frequency counter is not a very demanding thing in the hierarchy of TimeNut signals. You can drive any of them with some pretty simple logic gate based circuits. No need to spend a lot of money. Logic gate, yes. Comparator, no. This reminds me a lot of a similar discussion a couple of weeks ago. (where the issue boiled down to noise bandwidth) What is the problem with a comparator vs a logic gate? What makes the logic gate supperior? Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ 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] iGPS?
Any wide area and broadband military jammer is taking a big risk because the jammer is very easy to find. If Apple is buying into this then it is not military and they are looking to put it inside a phone or maybe a car. On Mon, May 18, 2015 at 11:06 AM, Brooke Clarke bro...@pacific.net wrote: Hi Bob: In the link in the message from Brian it explains that iGPS is for military users of the Iridium system. The key feature is to allow a moving vehicle to lock on the GPS signal while being jammed. They do that and also get a more accurate fix by using signals from the Iridium satellites. I see a potential problem in that the Iridium signals are close in frequency to GPS and a broad band jammer might cause a problem for both of them. Mail_Attachment -- Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html http://www.prc68.com/I/DietNutrition.html Bob Camp wrote: Hi “Orders of magnitude” more accurate … Right now, you can get around ~1 M in most areas. One order of magnitude would be 10 cm. More than one order of magnitude would be 10 mm. To me “orders” implies more than two, so that would be 1 mm. I guess everybody can toss out all their multi band GPS gear, there’s no need for it anymore. No need to put up all those expensive block III GPS sat’s either :) hm……I do believe the marketing boys have been playing with the numbers. You would have to start from a 50 M error to get them to make much sense based on what they are doing. === If you dig a bit more, Apple bought Coherent Navigation almost a half year ago. The main purpose appears to be merging their mapping software into Apple’s ill-fated maps program. Given that Iridium is a “pay’ service (as in $) you probably will not see it in run of the mill cell phones very soon …. Bob On May 17, 2015, at 7:07 PM, Chris Albertson albertson.ch...@gmail.com wrote: Anyone know anything about iGPS? Apparently the Iridium low orbit communications sats are now modified via software update to send signals that when combined with GPS allow for a receiver that is MUCH more precise and harder to jam and can work in urban areas better. Apple just bought a company that is building iGPS receivers. Looks like something that they might want to put inside a cell phone but when you have an orders of magnitude important in position you'd expect better timing too, or so I would think. Seems like a very smart idea if all that was required was a software upload to existing spacecraft. From what I read this is real, not a proposal another are real receivers being tested. -- Chris Albertson Redondo Beach, California ___ 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 unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Thunderbolt Height Error
Hi The simple answer is that Google maps may or may not be correct. There are a lot of examples of them being off by 10M or more. That said, my *guess* would be that the Thunderbolt is closer to the truth. Bob On May 18, 2015, at 2:34 AM, Demian Martin demianm@gmail.com wrote: I have 2 GPSDO's. A Thunderbolt and an Arbiter 1083A. The Arbiter is old but it works fine (and has a Wenzel 5 MHz streamline oscillator in it). It has the 1995 firmware issue, and I could get new firmware for it ($$) but I'm not using it as a clock, just a frequency source. I just moved and have re-setup both. They share an antenna. I got both to do a self survey. The Arbiter was really close to what Google maps indicate is my location. The Thunderbolt was about the same except it has me underground. The arbiter has the height as +30M. The Thunderbolt as -6M. What setting do I have wrong in the Thunderbolt? Would it affect the operation as a frequency standard in any way? Demian Martin San Leandro, CA 94577 ___ 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] iGPS?
Hi Brooke: In the original post that I was replying to, the concept was advocated as a “it goes into every iPhone on the planet”. That’s what I was commenting on. Bob On May 18, 2015, at 2:06 PM, Brooke Clarke bro...@pacific.net wrote: Hi Bob: In the link in the message from Brian it explains that iGPS is for military users of the Iridium system. The key feature is to allow a moving vehicle to lock on the GPS signal while being jammed. They do that and also get a more accurate fix by using signals from the Iridium satellites. I see a potential problem in that the Iridium signals are close in frequency to GPS and a broad band jammer might cause a problem for both of them. Mail_Attachment -- Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html http://www.prc68.com/I/DietNutrition.html Bob Camp wrote: Hi “Orders of magnitude” more accurate … Right now, you can get around ~1 M in most areas. One order of magnitude would be 10 cm. More than one order of magnitude would be 10 mm. To me “orders” implies more than two, so that would be 1 mm. I guess everybody can toss out all their multi band GPS gear, there’s no need for it anymore. No need to put up all those expensive block III GPS sat’s either :) hm……I do believe the marketing boys have been playing with the numbers. You would have to start from a 50 M error to get them to make much sense based on what they are doing. === If you dig a bit more, Apple bought Coherent Navigation almost a half year ago. The main purpose appears to be merging their mapping software into Apple’s ill-fated maps program. Given that Iridium is a “pay’ service (as in $) you probably will not see it in run of the mill cell phones very soon …. Bob On May 17, 2015, at 7:07 PM, Chris Albertson albertson.ch...@gmail.com wrote: Anyone know anything about iGPS? Apparently the Iridium low orbit communications sats are now modified via software update to send signals that when combined with GPS allow for a receiver that is MUCH more precise and harder to jam and can work in urban areas better. Apple just bought a company that is building iGPS receivers. Looks like something that they might want to put inside a cell phone but when you have an orders of magnitude important in position you'd expect better timing too, or so I would think. Seems like a very smart idea if all that was required was a software upload to existing spacecraft. From what I read this is real, not a proposal another are real receivers being tested. -- Chris Albertson Redondo Beach, California ___ 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] iGPS?
The parts of the iGPS story that I actually understand, make it sound like it will decrease acquisition time and especially decrease acquisition time in presence of jamming. Like how cellphone tower fixes can give a cellphone's GPS an initial guess at time/position and speed up GPS acquisition (aka aGPS). As cellphones move more towards wifi and away from traditional cellphone technologies, the initial Iridium fix may become more important. My grasp above, has nothing to do with orders of magnitude more precision in a fix. But I could see at least an order of magnitude or more in faster acquisition, as compared to a complete cold start. Tim N3QE On Sun, May 17, 2015 at 10:10 PM, Bob Camp kb...@n1k.org wrote: Hi “Orders of magnitude” more accurate … Right now, you can get around ~1 M in most areas. One order of magnitude would be 10 cm. More than one order of magnitude would be 10 mm. To me “orders” implies more than two, so that would be 1 mm. I guess everybody can toss out all their multi band GPS gear, there’s no need for it anymore. No need to put up all those expensive block III GPS sat’s either :) hm……I do believe the marketing boys have been playing with the numbers. You would have to start from a 50 M error to get them to make much sense based on what they are doing. === If you dig a bit more, Apple bought Coherent Navigation almost a half year ago. The main purpose appears to be merging their mapping software into Apple’s ill-fated maps program. Given that Iridium is a “pay’ service (as in $) you probably will not see it in run of the mill cell phones very soon …. Bob On May 17, 2015, at 7:07 PM, Chris Albertson albertson.ch...@gmail.com wrote: Anyone know anything about iGPS? Apparently the Iridium low orbit communications sats are now modified via software update to send signals that when combined with GPS allow for a receiver that is MUCH more precise and harder to jam and can work in urban areas better. Apple just bought a company that is building iGPS receivers. Looks like something that they might want to put inside a cell phone but when you have an orders of magnitude important in position you'd expect better timing too, or so I would think. Seems like a very smart idea if all that was required was a software upload to existing spacecraft. From what I read this is real, not a proposal another are real receivers being tested. -- Chris Albertson Redondo Beach, California ___ 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] TymServe 2100 was: The GPS 1995 problem and the Heol Design solution.
Hi The complexity is not in the data translation, it’s in the timing of the whole thing. The firmware in the TS2100 was designed and tested with a particular order of sentences and timing between them and the pps output of the Trimble ACE. Upset that timing (by delaying the data) and you may up upset the firmware’s expectations about when the data gets there. You may only “nuke” the firmware once a month, but that’s plenty of trouble. Since you have to do some pretty complex gyrations to translate the information, doing it all on a “character in/ character out” minimum delay basis is non-trivial. Even if you get that part of it working, you still have the ACE off in limbo as far as leap seconds are concerned. It has a very odd idea of when June 30th is going to be. It will leap at odd times. You will have to do a bit of testing to work out exactly when (or maybe if) it’s going to do a leap second. Not at all simple. Thus not at all cheap. Bob On May 18, 2015, at 4:00 PM, Sean Gallagher s...@wetstonetech.com wrote: Most likely all of them. There may still be some out there with GPS receivers made later in the year that still work but by the end of 2015 they will probably all be bad. The 1995 problem is actually with the GPS receiver which just plugs into the TS2100's. They can be used in other things as well and that's actually where I first caught it but didn't pick up on what it was. I think Bob Camp made a note about something like that but was suggesting against it since it will add complexity to the system. I don't know that it's possible though as it would have to do it in real time on the fly or you'll lose time in the calculation. I made the comment about the RPI projects I'd seen and adding in the 1023 weeks myself but from other time - nuts it would be very complex. Sent from my Verizon Wireless 4G LTE smartphone Original message From: Brooke Clarke bro...@pacific.net Date: 05/17/2015 18:32 (GMT-05:00) To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: [time-nuts] TymServe 2100 was: The GPS 1995 problem and the Heol Design solution. Hi Sean: Do you have any data on how many TymServe 2100 units have this problem? Would a solution be to add a daughter board between the existing GPS and the TymServe 2100 that would correct the year? This might be a straight forward PIC microcontroller. Mail_Attachment -- Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html http://www.prc68.com/I/DietNutrition.html Sean Gallagher wrote: Good afternoon everyone, So as most (all) of you are aware at this point what seems to be like all of the Trimble Ace III GPS receivers have looped around their entire lifespan and are setting the date back to 1995. This is affecting many people with the Datum/Symmetricom TymServe 2100 units. My company had two such units (we had purchased a second one when the +1 second UTC thing happened not realizing it was a firmware v3 and 4 problem) and also a slew of Datum 635/637 PCI cards which use the Trimble Ace III as well. After some scrounging around on the web I found that a company in France, Heol Design (http://www.heoldesign.com/), had created an Ace III clone. I contacted them for some information and a quote on what sounded the most promising. These were the N014 and N024 units which were quoted to me as 85 euro for the 014 and 90 euro for the 024. I also asked them if they thought their units would correct the date problem and they reached out to Trimble who apparently was not able (or willing?) to provide an answer. Olivier Descoubès with Heol Designs however was willing to work with me for testing purposes and sent me 2 of the N024 units so that I could test and see if they would work as true drop in replacements. I have attached the data sheets that I received on the units as well for your viewing. I'm not as technical as most of you so maybe you'll see something that I don't get that you can work with. The units came in yesterday after COB and so this morning was the moment of truth. Short answer to everything is they don't seem to work. I hooked it in to both of my 2100's first the older Datum branded one then the newer Symmetricom brand (although they look physically to be the exact same underlying board) really just to try and cover all my bases. I let the first one go for about an hour and the second for only half an hour since I was already thinking this was a bust. While it was hooked up though I telnetted in and went into the GPS menu. It gave me my Lat/Long position and the satellites command was able to show me that I had plenty of coverage, but it was unable to give me the time. After that I hooked it on to one of my 635PCI cards and got one of my backup servers going. I
Re: [time-nuts] TymServe 2100 was: The GPS 1995 problem and the Heol Design solution.
Most likely all of them. There may still be some out there with GPS receivers made later in the year that still work but by the end of 2015 they will probably all be bad. The 1995 problem is actually with the GPS receiver which just plugs into the TS2100's. They can be used in other things as well and that's actually where I first caught it but didn't pick up on what it was. I think Bob Camp made a note about something like that but was suggesting against it since it will add complexity to the system. I don't know that it's possible though as it would have to do it in real time on the fly or you'll lose time in the calculation. I made the comment about the RPI projects I'd seen and adding in the 1023 weeks myself but from other time - nuts it would be very complex. Sent from my Verizon Wireless 4G LTE smartphone Original message From: Brooke Clarke bro...@pacific.net Date: 05/17/2015 18:32 (GMT-05:00) To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: [time-nuts] TymServe 2100 was: The GPS 1995 problem and the Heol Design solution. Hi Sean: Do you have any data on how many TymServe 2100 units have this problem? Would a solution be to add a daughter board between the existing GPS and the TymServe 2100 that would correct the year? This might be a straight forward PIC microcontroller. Mail_Attachment -- Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html http://www.prc68.com/I/DietNutrition.html Sean Gallagher wrote: Good afternoon everyone, So as most (all) of you are aware at this point what seems to be like all of the Trimble Ace III GPS receivers have looped around their entire lifespan and are setting the date back to 1995. This is affecting many people with the Datum/Symmetricom TymServe 2100 units. My company had two such units (we had purchased a second one when the +1 second UTC thing happened not realizing it was a firmware v3 and 4 problem) and also a slew of Datum 635/637 PCI cards which use the Trimble Ace III as well. After some scrounging around on the web I found that a company in France, Heol Design (http://www.heoldesign.com/), had created an Ace III clone. I contacted them for some information and a quote on what sounded the most promising. These were the N014 and N024 units which were quoted to me as 85 euro for the 014 and 90 euro for the 024. I also asked them if they thought their units would correct the date problem and they reached out to Trimble who apparently was not able (or willing?) to provide an answer. Olivier Descoubès with Heol Designs however was willing to work with me for testing purposes and sent me 2 of the N024 units so that I could test and see if they would work as true drop in replacements. I have attached the data sheets that I received on the units as well for your viewing. I'm not as technical as most of you so maybe you'll see something that I don't get that you can work with. The units came in yesterday after COB and so this morning was the moment of truth. Short answer to everything is they don't seem to work. I hooked it in to both of my 2100's first the older Datum branded one then the newer Symmetricom brand (although they look physically to be the exact same underlying board) really just to try and cover all my bases. I let the first one go for about an hour and the second for only half an hour since I was already thinking this was a bust. While it was hooked up though I telnetted in and went into the GPS menu. It gave me my Lat/Long position and the satellites command was able to show me that I had plenty of coverage, but it was unable to give me the time. After that I hooked it on to one of my 635PCI cards and got one of my backup servers going. I started up the Datum application and it did go into GPS mode which was at first promising. Typically with these cards if there is a problem between the GPS receiver and the Datum card then it will automatically come up in Time Code mode and won't even recognize the GPS. I let it run for about an hour while I ran to lunch and when I came back it had still not put out time. My guess is that these new receivers use the Extended date format or whatever it's called that adds more bits on (3? - sorry I can't remember specifics) to correct the rollover and changes it from 15 years to like 157 or something like that. And it seems like this older equipment that a lot of timing solutions use cannot handle this new output and thus can't decode it. Again I'm just a Junior in college so this is all just theory but it's what my gut feeling is. I've also attached pictures of these new units. They are the same size and have the 8 pin stack. There is additionally a 10 pin stack that I had to trim down to get it to fit. Also the antenna connector is an SMB,
