Re: [time-nuts] The Problem with Time Timezones - Computerphile
On Thu, 08 May 2014 09:59:14 -0700 Brooke Clarke bro...@pacific.net wrote: Hi: A video that explains the difficulty in writing code that includes timezones:) https://www.youtube.com/watch?v=-5wpm-gesOY He left out Indian reservations. They get to choose if they want to be on daylight savings time or not. You might think it is not significant, but trust me, it you want to tour on an Indian reservation while your motel is of course off the reservation, you do need to keep track of this. ___ 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] Frequency of LC Tank
On 04/12/2014 03:23 PM, d...@irtelemetrics.com wrote: Magnus, You are very much on the track that I was thinking. I belive you are absolutly correct in that a 90 degree phase shift would be ideal. Coming into the conversation kinda late. Sounds like you're building an induction heater which is what I do professionally. You might want to read this page http://inductionheatertutorial.com/ I gave Jonathan the circuit. He improved on it and inserted a microprocessor into the PLL to stabilize it and make it more noise resistant. He has some very nice videos on Youtube under the handle imsmoother. Here's my page http://www.neon-john.net/Induction/Index.htm John -- John DeArmond Tellico Plains, Occupied TN http://www.fluxeon.com -- THE source for induction heaters http://www.neon-john.com-- email from here http://www.johndearmond.com -- Best damned Blog on the net PGP key: wwwkeys.pgp.net: BCB68D77 ___ 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] The Problem with Time Timezones - Computerphile
Ahh, but with Lady Heather you can specify the time zone offset (down to the second) and the when the daylight savings time switchovers occur. And from experience, I can tell you that the code to do it is a royal pain in the ass... not all that hard to do, but a pain to test. -- That is the problem. Even if someone gives you this code free and it works, then some years from now some country will change the date when they switch over to daylight savings or they even change a time zone offset. ___ 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] The Problem with Time Timezones - Computerphile
That's the magic of tz database for timezones and NIST leap-second file for leap seconds. The code stays same from year to year, but as politics changes timezones or IERS announces leapseconds, you just make sure you load the new tz file and leap-seconds file. Re-writing and re-testing code every time there's a change is such a losing proposition :-(. Updating a data file, that's a lot easier. http://tools.ietf.org/html/rfc6557 ftp://time.nist.gov/pub/leap-seconds.3535228800 On Fri, May 9, 2014 at 1:45 PM, Mark Sims hol...@hotmail.com wrote: Ahh, but with Lady Heather you can specify the time zone offset (down to the second) and the when the daylight savings time switchovers occur. And from experience, I can tell you that the code to do it is a royal pain in the ass... not all that hard to do, but a pain to test. -- That is the problem. Even if someone gives you this code free and it works, then some years from now some country will change the date when they switch over to daylight savings or they even change a time zone offset. ___ 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] The Problem with Time Timezones - Computerphile
hol...@hotmail.com said: Ahh, but with Lady Heather you can specify the time zone offset (down to the second) and the when the daylight savings time switchovers occur. And from experience, I can tell you that the code to do it is a royal pain in the ass... not all that hard to do, but a pain to test. Part of the problem is that when the daylight savings time switchovers occur changes over time. The problem is a whole lot easier if all you are interested in is converting the current UTC to the current local time. The *nix world uses the time-zone database. I assume it is available on Windows too. https://en.wikipedia.org/wiki/Tz_database -- 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] BeagleBone Black NTP server
Has anyone here made NTP run on BBB? My plan is to run NTP disciplined by my Trimble Thunderbolt on BBB. If someone has gotten there ahead of me I would like to follow in your footsteps rather than finding the mines in the minefield all by myself. :-) -- Brian Lloyd, WB6RQN/J79BPL 706 Flightline Drive Spring Branch, TX 78070 br...@lloyd.com +1.916.877.5067 ___ 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] BeagleBone Black NTP server
On Fri, 9 May 2014 15:55:08 -0500 Brian Lloyd br...@lloyd.com wrote: Has anyone here made NTP run on BBB? My plan is to run NTP disciplined by my Trimble Thunderbolt on BBB. If someone has gotten there ahead of me I would like to follow in your footsteps rather than finding the mines in the minefield all by myself. :-) I'm running NTP on it now, but not with GPS timing. ___ 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] BeagleBone Black NTP server
I too have ntp running on the BeagleBone Black, also without GPS interfaced. However, I stumbled across this website; http://the8thlayerof.net/2013/12/08/adafruit-ultimate-gps-cape-creating-custom-beaglebone-black-device-tree-overlay-file/ with details on interfacing GPS but I haven't dug into the details yet but it looks like a good start. cheers, Graham ve3gtc On 2014-05-10 00:16, nuts wrote: On Fri, 9 May 2014 15:55:08 -0500 Brian Lloyd br...@lloyd.com wrote: Has anyone here made NTP run on BBB? My plan is to run NTP disciplined by my Trimble Thunderbolt on BBB. If someone has gotten there ahead of me I would like to follow in your footsteps rather than finding the mines in the minefield all by myself. :-) I'm running NTP on it now, but not with GPS timing. ___ 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] BeagleBone Black NTP server
On Friday, May 9, 2014, nuts n...@lazygranch.com wrote: On Fri, 9 May 2014 15:55:08 -0500 Brian Lloyd br...@lloyd.com javascript:; wrote: Has anyone here made NTP run on BBB? My plan is to run NTP disciplined by my Trimble Thunderbolt on BBB. If someone has gotten there ahead of me I would like to follow in your footsteps rather than finding the mines in the minefield all by myself. :-) I'm running NTP on it now, but not with GPS timing. Ok. Did you build from source or did you have binaries? -- Brian Lloyd, WB6RQN/J79BPL 706 Flightline Drive Spring Branch, TX 78070 br...@lloyd.com +1.916.877.5067 ___ 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] BeagleBone Black NTP server
I used the distribution of ntp provided in the Angstrom repository. I believe there is a version of Debian available for the Beaglebone Black and that too will have ntp in it's repository. cheers, Graham ve3gtc On 2014-05-10 00:32, Brian Lloyd wrote: On Friday, May 9, 2014, nuts n...@lazygranch.com wrote: On Fri, 9 May 2014 15:55:08 -0500 Brian Lloyd br...@lloyd.com javascript:; wrote: Has anyone here made NTP run on BBB? My plan is to run NTP disciplined by my Trimble Thunderbolt on BBB. If someone has gotten there ahead of me I would like to follow in your footsteps rather than finding the mines in the minefield all by myself. :-) I'm running NTP on it now, but not with GPS timing. Ok. Did you build from source or did you have binaries? ___ 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] BeagleBone Black NTP server
On Fri, May 9, 2014 at 1:55 PM, Brian Lloyd br...@lloyd.com wrote: Has anyone here made NTP run on BBB? My plan is to run NTP disciplined by my Trimble Thunderbolt on BBB. NTP is likely already installed on the BBB. It ships with the BBB. Some configuration is needed to enable the service. Do this first and verify you can run using Internet pool servers. Then after this is running you physically connect your GPS then add lines in NTP's config file telling NTP you have added another ref. clock. -- 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] BeagleBone Black NTP server
On Fri, May 9, 2014 at 7:26 PM, Graham planoph...@aei.ca wrote: I too have ntp running on the BeagleBone Black, also without GPS interfaced. However, I stumbled across this website; http://the8thlayerof.net/2013/12/08/adafruit-ultimate-gps- cape-creating-custom-beaglebone-black-device-tree-overlay-file/ with details on interfacing GPS but I haven't dug into the details yet but it looks like a good start. Wow! Yes. The Debian packages are all out there. I am making a custom cape that just brings the 5V 1pps in and converts it to 3.3V for compatibility with the BBB. First step is to configure ntp to run and then add in the hardware support for 1pps and taking to the T-bolt. I will keep all apprised of my progress. Thank you much! cheers, Graham ve3gtc On 2014-05-10 00:16, nuts wrote: On Fri, 9 May 2014 15:55:08 -0500 Brian Lloyd br...@lloyd.com wrote: Has anyone here made NTP run on BBB? My plan is to run NTP disciplined by my Trimble Thunderbolt on BBB. If someone has gotten there ahead of me I would like to follow in your footsteps rather than finding the mines in the minefield all by myself. :-) I'm running NTP on it now, but not with GPS timing. ___ 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. -- Brian Lloyd, WB6RQN/J79BPL 706 Flightline Drive Spring Branch, TX 78070 br...@lloyd.com +1.916.877.5067 ___ 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] Low cost GPS module for 100ns timestamping error
On 06/05/2014 02:24, Chris Albertson wrote: On Mon, May 5, 2014 at 6:55 AM, Tony tn...@toneh.demon.co.uk wrote: Yes - that is exactly what I intended. The problem though is maintaining sufficient accuracy during periods when the GPS clock is unavailable or unreliable (perhaps due to local interference), but I don't have any handle on how long that may be or how often it occurs. Clearly there are no absolute guarantees - eg. the GPS selective availability could be turned on again in exceptional circumstances, so I accept that 100ns accuracy can't be absolutely guaranteed. I assumed you were making these measurements at a fixed location.You don't loose GPS signal often. Onece you have the antenna in a location that works it continues to work, most of the time. Drop outs are rare in a fixed system after you gt it working.It's different in a moving vehicle. Thanks Chris - that's just the information I was looking for. Yes it would be at a fixed location; it wouldn't be a problem checking that it had good reception during installation. The question then is, in the experience of users of GPS timing references, for a decent but low cost receiver with a reasonably well sited antenna and assuming there is no significant interference, how long and how frequently is time synchronisation lost? If for example it's only 2 or 3 seconds every few weeks, then there isn't much of a problem. If 5 minute outages occur every few days then the holdover performance of the local oscillator is much more critical. As said above, once it works it pretty much continues to work. With a very good antenna site (mine is on a 4 foot above the roof line with a 360 degree view of the sky) I've never had a loss of signal except as a test. But then I don't look for them either. If you do get a loss of signal then all that happens is my GPSDO controller never updates the local oscillator. It sticks at the last setting. So the drift depends on how good is the local oscillator. I have two. One is a $15 crystal. It can run for hours before I can detect any drift (I my case that is a few ns of phase drift) Certainly your example of 5 minutes per day of GPS outage would be no problem at all even for a moderate quality OCXO. My other oscillator is a Rubidium. It is the $40 FE-5680 from eBay and it can go for days with no GPS corrections (at the few ns level) That's interesting. What model is the $15 oscillator? Is it an OXCO? Unfortunately the power consumption of the OXCOs I've looked at are much too high at 1W. However this TCXO is both cheap and remarkably comprehensively specified: http://media.digikey.com/pdf/Data%20Sheets/NDK%20PDFs/NT2016SA-16.368000_MHZ-NTG1.pdf Its a 16.368MHz oscillator for less than $2 and uses 1.5mA . Unusually the data sheet specifies not only the max temperature stability at +/- .5ppm from -10 to +70C, but also the max frequency/temperature slope at +/- .05ppm/C . It also specifies short term stability at max 1ppb over .1s. Quite a remarkable datasheet for a low cost part - I've not found any other low cost oscillator with either of those specifications, and even some (most?) of the OXCO don't specify the freq/temp slope. Having said that, I can't find the same datasheet anywhere else - those on NDK's website are less comprehensive. Perhaps those on Digikey's site are out of date, NDK not wanting to guarantee those specs for such a low cost part. I intend to try one and see how it performs in a box, with some insulation, when moved into a sunny spot after being shaded for a while. What about in more difficult circumstances - eg. in urban environment with an antenna that has a restricted view of the sky? Not that I expect to operate in such circumstances but it would be interesting to get a feel for how good or bad timing is maintained in less favourable situations. It all depends on the quality of the oscillator. But again you would fiddle with the antenna until it worked as best it could then you don't se much change in a fixed location system. The other thing that saves you is that for timing at a fixed location the GPS only needs ONE satellite. With any reasonable setup yo are likely to have one sat visible at all times. But isn't that only supported by 'timing' GPS modules that allow you to specify the location? But they are rather more expensive than the common navigation type modules - are there sub $15 modules that support that single-satellite timing feature? Thanks, Tony H ___ 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] BeagleBone Black NTP server
On Fri, May 9, 2014 at 8:49 PM, Chris Albertson albertson.ch...@gmail.comwrote: On Fri, May 9, 2014 at 1:55 PM, Brian Lloyd br...@lloyd.com wrote: Has anyone here made NTP run on BBB? My plan is to run NTP disciplined by my Trimble Thunderbolt on BBB. NTP is likely already installed on the BBB. It ships with the BBB. That may be the case for the Angstrom distro but it is not the case for the Debian distro, which seems to be the future direction of BBB. Some configuration is needed to enable the service. Do this first and verify you can run using Internet pool servers. Then after this is running you physically connect your GPS then add lines in NTP's config file telling NTP you have added another ref. clock. This link: http://the8thlayerof.net/2013/12/08/adafruit-ultimate-gps-cape-creating-custom-beaglebone-black-device-tree-overlay-file/ Seems to have the bulk of the requisite information including building a GPS cape using the Adafruit GPS module. See: https://www.adafruit.com/product/746 This isn't a timing receiver but would probably be adequate for NTP. But since I already have a T-bolt I figured I would use that as my timing source. -- Brian Lloyd, WB6RQN/J79BPL 706 Flightline Drive Spring Branch, TX 78070 br...@lloyd.com +1.916.877.5067 ___ 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] BeagleBone Black NTP server
I have the adafruit and a ublox-6T each mated to raspberry pi's. With NTP they are essentially indistinguishable. I have something other than NTP in mind for the 6Tpi. Sent from my iPad On May 9, 2014, at 9:32 PM, Brian Lloyd br...@lloyd.com wrote: On Fri, May 9, 2014 at 8:49 PM, Chris Albertson albertson.ch...@gmail.comwrote: On Fri, May 9, 2014 at 1:55 PM, Brian Lloyd br...@lloyd.com wrote: Has anyone here made NTP run on BBB? My plan is to run NTP disciplined by my Trimble Thunderbolt on BBB. NTP is likely already installed on the BBB. It ships with the BBB. That may be the case for the Angstrom distro but it is not the case for the Debian distro, which seems to be the future direction of BBB. Some configuration is needed to enable the service. Do this first and verify you can run using Internet pool servers. Then after this is running you physically connect your GPS then add lines in NTP's config file telling NTP you have added another ref. clock. This link: http://the8thlayerof.net/2013/12/08/adafruit-ultimate-gps-cape-creating-custom-beaglebone-black-device-tree-overlay-file/ Seems to have the bulk of the requisite information including building a GPS cape using the Adafruit GPS module. See: https://www.adafruit.com/product/746 This isn't a timing receiver but would probably be adequate for NTP. But since I already have a T-bolt I figured I would use that as my timing source. -- Brian Lloyd, WB6RQN/J79BPL 706 Flightline Drive Spring Branch, TX 78070 br...@lloyd.com +1.916.877.5067 ___ 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] BeagleBone Black NTP server
I have the adafruit and a ublox-6T each mated to raspberry pi's. With NTP they are essentially indistinguishable. I have something other than NTP in mind for the 6Tpi. Bill, That makes sense. Your GPS receivers are about 1000x more accurate than necessary. NTP lives in the millisecond to microsecond world, and GPS receivers in a nanosecond world. /tvb ___ 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] BeagleBone Black NTP server
On Fri, 9 May 2014 21:59:22 -0500 Bill Dailey docdai...@gmail.com wrote: I have the adafruit and a ublox-6T each mated to raspberry pi's. With NTP they are essentially indistinguishable. I have something other than NTP in mind for the 6Tpi. Sent from my iPad On May 9, 2014, at 9:32 PM, Brian Lloyd br...@lloyd.com wrote: On Fri, May 9, 2014 at 8:49 PM, Chris Albertson albertson.ch...@gmail.comwrote: On Fri, May 9, 2014 at 1:55 PM, Brian Lloyd br...@lloyd.com wrote: Has anyone here made NTP run on BBB? My plan is to run NTP disciplined by my Trimble Thunderbolt on BBB. NTP is likely already installed on the BBB. It ships with the BBB. That may be the case for the Angstrom distro but it is not the case for the Debian distro, which seems to be the future direction of BBB. Some configuration is needed to enable the service. Do this first and verify you can run using Internet pool servers. Then after this is running you physically connect your GPS then add lines in NTP's config file telling NTP you have added another ref. clock. This link: http://the8thlayerof.net/2013/12/08/adafruit-ultimate-gps-cape-creating-custom-beaglebone-black-device-tree-overlay-file/ Seems to have the bulk of the requisite information including building a GPS cape using the Adafruit GPS module. See: https://www.adafruit.com/product/746 This isn't a timing receiver but would probably be adequate for NTP. But since I already have a T-bolt I figured I would use that as my timing source. -- I can tell you that the BBB is really reliable. You don't hear that about the R. Pi, plus it is about 4x the CPU power of the R PI, granted at $20 more cost. The R Pi has a better GPU if you need resolution. I'm running dump1090 on the BBB, for those familiar with the project. [Probably just satellite Dave.] The only issue I found with the BBB is when I booted my router and the connection to the BBB didn't fire up. I probed the BBB with the serial port connector and it was running just fine, so I don't know why the router didn't connect to it. I booted the BBB and it did connect to the router. Reliability is of course key to any timing reference. Angstrom uses systemd. The R Pi is still on initd IIRC. Note a bug on the BBB is if you use a cape, it blocks the connector to the serial port. ___ 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] BeagleBone Black NTP server
On Fri, May 9, 2014 at 4:55 PM, Brian Lloyd br...@lloyd.com wrote: Has anyone here made NTP run on BBB? Yes. I really feel like I was just taking about this but I can't find any email at the moment. I did build both NTPD and a kernel but just NTPD is accpetable with the current Ubuntu build I use (14.04 LTS/3.8.0). I started with the http://the8thlayerof.net/ stuff using the same bits (conveniently all 3.3V) although the dts file and gpio usage is kernel specific (and will be changing again with the new boards). remote refid st t when poll reach delay offset jitter == x127.127.20.0.ADAU. 0 l78 3770.000 112.495 29.833 o127.127.22.0.GPPS. 0 l58 3770.0000.001 0.008 *128.205.85.72 .GPPS. 1 u78 3770.473 -0.021 0.035 ___ 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] BeagleBone Black NTP server
On Fri, May 9, 2014 at 11:38 PM, nuts n...@lazygranch.com wrote: I can tell you that the BBB is really reliable. You don't hear that about the R. Pi, I find them comparable. My Pi has actually run longer. I don't expect either to be able to run a year without crashing. Note a bug on the BBB is if you use a cape, it blocks the connector to the serial port. I use stacking headers (the wrong way) to lift the cape. I'd rather have the console port than be able to close a case. ___ 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] PRS10 rubidium on eBay
Hi, I'm selling a nice PRS10 on eBay if anyone is interested. With manual and schematics. Works great! Cheers, Corby Dawson ___ 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.
