Re: [time-nuts] GPS NTP update on Mac OS-X 10.7.4
I recently connected up a USB GPS to my Linux box and found it quite easy to get NTP to up from the GPS. I was hoping to get the same GPS to update the Mac running Lion 10.7.4, however, it has been a very frustrating uphill battle. Has anybody managed to get GPS NTP update working on OS-X? You will probably get much better answers to NTP questions over on the NTP lists. http://lists.ntp.org/listinfo Down near the bottom is questions GPS over USB generally doesn't work very well. You will probably get better results over the net. The problem isn't USB polling, it's firmware that adds about 100 ms of wander. By wander I mean low frequency drift. It's too slow to filter out. Here is a graph from a SiRF III, the most common chipset in low cost USB GPS devices. Most others are similar. http://www.megapathdsl.net/~hmurray/ntp/GPSSiRF-off.gif If anybody finds a good one, please let me know. I did a sum link to /dev/gps0 and can cat the output and see the NMEA stream of alternate $GPRMC and $GPZDA messages, I just cannot get it to accept the gps as a peer. The GPRMC sentence has a flag to tell you if it is seeing enough satellites. Are you seeing A or V? I think A is good and V is bad. -- These are my opinions. I hate spam. ___ 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 cabling questions
Sometimes the cone of protection simply does not exist. A couple of weeks ago I had to respons to one of my sites which contains an 800 foot tower. While there a large storm cell developed and a severe thunderstorm ensued. Shortly before leaving lighting hit the tower which was unnerving enough. But as I was walking out the door to get in the truck, another strike hit the ground about 200 yards in front of me. So much for protection. The house I live in is a 50 year-old two-story structure with metal siding. After moving in ten years ago and getting to know the neighbors, I was hearing rumors about the old lady who previously owned it having an issue of smelling smoke in the house shortly after a lightning storm occurred and having noticed a nearby strike. The fire department responded and investigated but could not find anything. After moving in I decided to remodel the second floor. As I was demo'ing the walls, I came upon the older style asphalt covered cloth AC wiring in one outside wall with its insulation completely burned away over a couple of vertical feet. Fortunately the rock wool insulation in the wall refused to continue ignition and the burning ceased. Additional investigation revealed that the main lightning strike had hit the tree next to the house and a secondary streamer traveled over to the siding. But this is where it gets interesting... The streamer hit the metal siding and under that location was a nail that apparently was fastening the old lap siding (under the later added metal overlay). The lightning then arced over to this nail which extended through the under sheath and then to the AC wire starting the fire. Looking at the point of the nail tip I found copper that was deposited from the wire over to the nail. The migration indicated that the lightning strike had been of negative polarity given the propensity for metals to migrate from the positive to the negative electrodes in an arcing situation. Greg Hi gang Just to upset the apple cart a bit, high trees do not necessarily protect a large area from lightning. In my past life as a range officer at a large shooting facility, we were hit by lightning directly in front of the firing line during a storm. The tree line was about 20 to 30 ft behind us and at least 50+ feet higher. There was even evidence of arcing between 2 pieces of conduit stuck in the ground about 5 ft apart. first and last time I saw a fire ball. For induced charges from nearby strikes nothing beats a good ground and lightning protector system. If a direct hit, I hope your insurance is paid up. My gps antennas are about 25 above ground just above my roof line. The mast is grounded to 2 ground rods and the coax fed through gas tube lightning protects. No problems even with hits several hundred yards away. Ewing (Rix) Seacord K2AVP/4/499 ___ 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] Fwd: GPS NTP update on Mac OS-X 10.7.4
Thanks Hal On 13/06/2012, at 10:08 AM, Hal Murray wrote: I recently connected up a USB GPS to my Linux box and found it quite easy to get NTP to up from the GPS. I was hoping to get the same GPS to update the Mac running Lion 10.7.4, however, it has been a very frustrating uphill battle. Has anybody managed to get GPS NTP update working on OS-X? You will probably get much better answers to NTP questions over on the NTP lists. http://lists.ntp.org/listinfo Down near the bottom is questions I'll look at ntp.org GPS over USB generally doesn't work very well. You will probably get better results over the net. I will be in an entirely stand alone situation and therefore GPS is my best timekeeping option for WSPR and WSJT - EME ops. The problem isn't USB polling, it's firmware that adds about 100 ms of wander. By wander I mean low frequency drift. It's too slow to filter out. Here is a graph from a SiRF III, the most common chipset in low cost USB GPS devices. Most others are similar. http://www.megapathdsl.net/~hmurray/ntp/GPSSiRF-off.gif If anybody finds a good one, please let me know. I've had a UBLox chip on a board working with my Linux laptop perfectly well, however OSX will just not allow the setup to work. I did a sum link to /dev/gps0 and can cat the output and see the NMEA stream of alternate $GPRMC and $GPZDA messages, I just cannot get it to accept the gps as a peer. The GPRMC sentence has a flag to tell you if it is seeing enough satellites. Are you seeing A or V? I think A is good and V is bad. I am seeing satellites and can cat the output of the device OS X will just not allow to to connect to 127.127.20.0, same device plugged into the Linux laptop works very well - just cannot get NTP in OS X to add it as a peer -- These are my opinions. I hate spam. ___ 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 NTP update on Mac OS-X 10.7.4
On Wed, Jun 13, 2012 at 3:08 AM, Hal Murray hmur...@megapathdsl.net wrote: Has anybody managed to get GPS NTP update working on OS-X? Yes, All Macs come with NTP already installed. (Version 4.2.6) All you need to do is replace the binary that lives in /usr/sbin. and edit the .conf file in /private/etc/ntp-restrict.conf Macs are quite a bit like BSD at that level. 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] GPS NTP update on Mac OS-X 10.7.4
On 13/06/2012, at 4:00 PM, Chris Albertson wrote: On Wed, Jun 13, 2012 at 3:08 AM, Hal Murray hmur...@megapathdsl.net wrote: Has anybody managed to get GPS NTP update working on OS-X? Yes, All Macs come with NTP already installed. (Version 4.2.6) All So Chris have you managed to get a GPS updating NTP as a peer on Mac OS X 10.7.4? Linux Ubuntu 12.04 has NTP 4.2.6p3 and that works OK you need to do is replace the binary that lives in /usr/sbin. Replace with what? and edit the .conf file in /private/etc/ntp-restrict.conf I have already edited both these conf files but still get: key_expire: at 0 associd 7474 peer_clear: at 0 next 1 associd 7474 refid INIT addto_syslog: refclock_open /dev/gps0: Operation not permitted Just will not allow association as a peer. Permissions of devices and directories are all OK addto_syslog: 127.127.20.0 interface 127.0.0.1 - (null) key_expire: at 0 associd 7475 peer_clear: at 0 next 2 associd 7475 refid INIT event at 0 17.171.4.13 8011 81 mobilize assoc 7475 newpeer: 192.168.43.12-17.171.4.13 mode 3 vers 4 poll 6 10 flags 0x1 0x1 ttl 0 key addto_syslog: DNS time.apple.com. ttl 3767 addto_syslog: DNS time.apple.com. minpoll 9 addto_syslog: DNS time.apple.com. maxpoll 12 addto_syslog: DNS time.apple.com. +iburst key_expire: at 0 associd 7476 peer_clear: at 0 next 3 associd 7476 refid INIT event at 0 17.83.253.7 8011 81 mobilize assoc 7476 newpeer: 192.168.43.12-17.83.253.7 mode 3 vers 4 poll 6 10 flags 0x1 0x1 ttl 0 key addto_syslog: DNS time.asia.apple.com. ttl 3834 addto_syslog: DNS time.asia.apple.com. minpoll 9 addto_syslog: DNS time.asia.apple.com. maxpoll 12 addto_syslog: DNS time.asia.apple.com. +iburst key_expire: at 0 associd 7477 peer_clear: at 0 next 4 associd 7477 refid INIT event at 0 129.180.1.14 8011 81 mobilize assoc 7477 newpeer: 192.168.43.12-129.180.1.14 mode 3 vers 4 poll 6 10 flags 0x1 0x1 ttl 0 key key_expire: at 0 associd 7478 peer_clear: at 0 next 5 associd 7478 refid INIT event at 0 129.180.126.10 8011 81 mobilize assoc 7478 newpeer: 192.168.43.12-129.180.126.10 mode 3 vers 4 poll 6 10 flags 0x1 0x1 ttl 0 key Macs are quite a bit like BSD at that level. 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] Thunderbolt cabling questions
Hi Greg, As I recall hearing it, the cone of protection is really just an area where the probability of a strike is much reduced. The cone of protection extends half as far as the lightning rod is high. If your rod was 800 feet high, the protection cone would extend 400 feet from the base of the rod in all directions. 200 yards is 600 feet, so I would consider that well outside of the cone. -Chuck Harris Gregory Muir wrote: Sometimes the cone of protection simply does not exist. A couple of weeks ago I had to respons to one of my sites which contains an 800 foot tower. While there a large storm cell developed and a severe thunderstorm ensued. Shortly before leaving lighting hit the tower which was unnerving enough. But as I was walking out the door to get in the truck, another strike hit the ground about 200 yards in front of me. So much for protection. ... ___ 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] Paper about DCF77 performance
On 6/13/2012 3:46 PM, Daniel Engeler wrote: Hi, This is my first post to this mailing list. I wrote a paper about the German longwave time transmitter DCF77 which you may find interesting. Here is the link, unfortunately I am not allowed to post the full PDF: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=arnumber=6202411 Performance Analysis and Receiver Architectures of DCF77 Radio-Controlled Clocks, by Daniel Engeler IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control (May 2012) Abstract: DCF77 is a longwave radio transmitter located in Germany. Atomic clocks generate a 77.5-kHz carrier which is amplitude- and phase-modulated to broadcast the official time. The signal is used by industrial and consumer radio-controlled clocks. DCF77 faces competition from the Global Positioning System (GPS) which provides higher accuracy time. Still, DCF77 and other longwave time services worldwide remain popular because they allow indoor reception at lower cost, lower power, and sufficient accuracy. Indoor longwave reception is challenged by signal attenuation and electromagnetic interference from an increasing number of devices, particularly switched-mode power supplies. This paper introduces new receiver architectures and compares them with existing detectors and time decoders. Simulations and analytical calculations characterize the performance in terms of bit error rate and decoding probability, depending on input noise and narrowband interference. The most promising detector with maximum-likelihood time decoder displays the time in less than 60 s after powerup and at a noise level of Eb/N0 = 2.7 dB, an improvement of 20 dB over previous receivers. A field-programmable gate array-based demonstration receiver built for the purposes of this paper confirms the capabilities of these new algorithms. The findings of this paper enable future high-performance DCF77 receivers and further study of indoor longwave reception. ___ 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. Daniel Might be a great read for us time-nuts. Unfortunately we have no access to the ieee site so it will go unread and appreciated. Regards Paul ___ 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] Paper about DCF77 performance
Would be interesting if I can read it. As far as I know even the IEEE grants the right to the author of his paper to locate it on his own web-site for public download. Thanks - Henry paul schrieb: On 6/13/2012 3:46 PM, Daniel Engeler wrote: Hi, This is my first post to this mailing list. I wrote a paper about the German longwave time transmitter DCF77 which you may find interesting. Here is the link, unfortunately I am not allowed to post the full PDF: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=arnumber=6202411 Daniel Might be a great read for us time-nuts. Unfortunately we have no access to the ieee site so it will go unread and appreciated. Regards Paul -- ehydra.dyndns.info ___ 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] Paper about DCF77 performance
Hi Do they grant the right, or do people just get away with it? Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of ehydra Sent: Wednesday, June 13, 2012 4:24 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Paper about DCF77 performance Would be interesting if I can read it. As far as I know even the IEEE grants the right to the author of his paper to locate it on his own web-site for public download. Thanks - Henry paul schrieb: On 6/13/2012 3:46 PM, Daniel Engeler wrote: Hi, This is my first post to this mailing list. I wrote a paper about the German longwave time transmitter DCF77 which you may find interesting. Here is the link, unfortunately I am not allowed to post the full PDF: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=arnumber=6202411 Daniel Might be a great read for us time-nuts. Unfortunately we have no access to the ieee site so it will go unread and appreciated. Regards Paul -- ehydra.dyndns.info ___ 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] Another ThunderBolt cabling question
13/06/2012 22:27 About to do the permanent installation, if I bring two leads from the 10 MHz and 1 PPS BNC sockets on the TB to a panel in my shck can i have say 5 BNC sockets on the panel wired in parallel, with the lead from the 10 MHz socket on the TB feeding them all? And a single socket for the 1 PPS? Any need to screen the back of the socket panel, or enclose it in a metal box? Cheers. Oh, I have been running lady Heather for a while tonight, here's a screen capture, does it look OK, ther's suddenly just two traces appeared? Thanks. http://www.chriswilson.tv/heather.png -- Best Regards, Chris Wilson. mailto: ch...@chriswilson.tv ___ 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] Another ThunderBolt cabling question
Sure enough the Thunderbolt will be able to drive five BNC jacks just fine. When you get into problems is when you try and plug stuff into the sockets. Kidding aside, really what you plug into hit is what matters. Three is easy, five is kind of pushing it without a distribution amp. All depends on what you are plugging in. For driving multiple piece of test equipment the conventional way is to use a few T to connecter and daisy chain the cable then at the end connect a 50 ohm terminator. I think this setup gets a better signal without so many reflections In the real world your plan would work fine. Most test equipment has well engineered 10MHz input and can work on anything you give it. But in this case it is cheap and easy to simply use some TEEs. On Wed, Jun 13, 2012 at 2:33 PM, Chris Wilson ch...@chriswilson.tv wrote: 13/06/2012 22:27 About to do the permanent installation, if I bring two leads from the 10 MHz and 1 PPS BNC sockets on the TB to a panel in my shck can i have say 5 BNC sockets on the panel wired in parallel, with the lead from the 10 MHz socket on the TB feeding them all? And a single socket for the 1 PPS? Any need to screen the back of the socket panel, or enclose it in a metal box? Cheers. Oh, I have been running lady Heather for a while tonight, here's a screen capture, does it look OK, ther's suddenly just two traces appeared? Thanks. http://www.chriswilson.tv/heather.png -- Best Regards, Chris Wilson. mailto: ch...@chriswilson.tv ___ 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] Paper about DCF77 performance
Do they grant the right, or do people just get away with it? We used to get away with it by publishing an in-house research report that was a preliminary version of what turned into the paper. That was many years ago, before the web. We actually printed hard copies. We had good in-house editors so the preliminary version was pretty good, maybe even better if interesting stuff had to be trimmed for the official paper. Matt Blaze has a good blog entry on this mess: Why do IEEE and ACM act against the interests of scholars? http://www.crypto.com/blog/copywrongs/ Daniel: Your timing was interesting. We just had a discussion on this topic a few days ago. If you want to review it, it's in the archives. Subject is Paywall rant, but a few comments probably rolled over to a few other threads. If you don't know how to find the archives, poke me off-list. -- These are my opinions. I hate spam. ___ 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] Another ThunderBolt cabling question
You probably should not drive several devices in parallel from one output. They may have fixed 50 ohm terminators. If not, it is best to daisy the cable from one device to the next and terminate the end device with 50 ohms. Also, that version of Lady Heather is very old. You should get the V 3.0 beta from the KE5FX web site. ___ 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] Another ThunderBolt cabling question
No you can't load the 10MHz (or the PPS) with five instruments in parallel. You need a distribution amplifier. Dave -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Wilson Sent: 13 June 2012 22:33 To: Discussion of precise time and frequency measurement Subject: [time-nuts] Another ThunderBolt cabling question 13/06/2012 22:27 About to do the permanent installation, if I bring two leads from the 10 MHz and 1 PPS BNC sockets on the TB to a panel in my shck can i have say 5 BNC sockets on the panel wired in parallel, with the lead from the 10 MHz socket on the TB feeding them all? And a single socket for the 1 PPS? Any need to screen the back of the socket panel, or enclose it in a metal box? Cheers. Oh, I have been running lady Heather for a while tonight, here's a screen capture, does it look OK, ther's suddenly just two traces appeared? Thanks. http://www.chriswilson.tv/heather.png -- Best Regards, Chris Wilson. mailto: ch...@chriswilson.tv ___ 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] Another ThunderBolt cabling question
Hi That all looks very normal. LH can scale the graph on it's own. I *know* that's true because it couldn't have been my typing on the keyboard that did it. That's my story and I'm sticking to it :)…… Your DAC voltage looks good and the oscillator seems to be settling well. I'd say you are running ok. I'd run coax for both the 1 pps and the 10 MHz. One pps jack should be plenty for now. If you run multiple jacks for the 10 MHz, rig up a simple resistive splitter. Bob On Jun 13, 2012, at 5:33 PM, Chris Wilson wrote: 13/06/2012 22:27 About to do the permanent installation, if I bring two leads from the 10 MHz and 1 PPS BNC sockets on the TB to a panel in my shck can i have say 5 BNC sockets on the panel wired in parallel, with the lead from the 10 MHz socket on the TB feeding them all? And a single socket for the 1 PPS? Any need to screen the back of the socket panel, or enclose it in a metal box? Cheers. Oh, I have been running lady Heather for a while tonight, here's a screen capture, does it look OK, ther's suddenly just two traces appeared? Thanks. http://www.chriswilson.tv/heather.png -- Best Regards, Chris Wilson. mailto: ch...@chriswilson.tv ___ 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] Paper about DCF77 performance
On 6/13/12 1:38 PM, Bob Camp wrote: Hi Do they grant the right, or do people just get away with it? it is formally granted.. the IEEE instructions for authors or something like that talks about it. You can put your own papers up on your own website, and you make sure you have appropriate attribution, etc. I'll look for the reference. ___ 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] Paper about DCF77 performance
Hoi Dani! I see you've found the time-nuts as well :-) On Wed, 13 Jun 2012 21:46:56 +0200 Daniel Engeler enge...@alumni.ethz.ch wrote: This is my first post to this mailing list. I wrote a paper about the German longwave time transmitter DCF77 which you may find interesting. Here is the link, unfortunately I am not allowed to post the full PDF: There is an easy way to get around that: Prepare a second paper with more data in it (all that stuff that IEEE tends to get rid of during the publication process) and put that onto your website. http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=arnumber=6202411 Performance Analysis and Receiver Architectures of DCF77 Radio-Controlled Clocks, by Daniel Engeler IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control (May 2012) Nice paper. I haven't had time to read it yet, but a few comments after i skimmed it: * you have a lot of simulation and measurments on BER vs SNR. For time-nutty needs that's not so relevant. An ADEV plot would be much more informative on the stability. * Also some data on the absolute timing variations vs time would be nice to have. * Fig 23 shows a very complex board. Given that you only have a relatively simple analog stage and an FPGA i wonder what the rest is for. * You use an LTC1562 8th order bandpass: Do you compensate for it's frequency dependend delay and its variation? Or is negligible compared to the antenna? * Do you do any temperature stabilization? * What kind of reference oscillator do you use? * You talk about 20 to 50ppm variations for XO's, are you aware that these are maximum variation including production variabiltiy and that the stability of an good XO is usually in the range of a few ppm in office conditions (i've measured an XO in a PC that showed a long term (months) stability in the ppb range) * Why did you use an FPGA and not a simple DSP or one of the more powerfull uC's like an Cortex-M3/4? The algorigthms don't look computationally intensive. And that would simplify the development considerably. * Where did you do your measurements? In Schlieren? * What is the application you had in mind while developing this? Attila Kinali -- Why does it take years to find the answers to the questions one should have asked long ago? ___ 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.
