[time-nuts] Using GPS to Fine Tune a Rubidium Frequency Standard.
Does anyone have a copy of the QEX 2013 november article(Bill Kaune) Using GPS to Fine Tune a Rubidium Frequency Standard? I´m really interested in this subject, but I can´t find this magazine in Sweden. I have contacted QEX, but it is very difficult to buy back-issues. Have any one built this frequency standard and can tell me more about the project? You can access the source code for the project here: http://www.arrl.org/files/file/QEX%20Binaries/2013/November_13/11x13_Kaune_PIC_Code.zip /Anders ___ 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] Using GPS to Fine Tune a Rubidium Frequency Standard.
I do not subscribe to QEX, but I know that all of the ARRL periodicals for 2013 (QST, NCJ and QEX) are on one CD and it is available now from ARRL and its distributors. HTH... 73, geo - n4ua On Fri, Mar 21, 2014 at 9:20 AM, Anders Time anderst...@gmail.com wrote: Does anyone have a copy of the QEX 2013 november article(Bill Kaune) Using GPS to Fine Tune a Rubidium Frequency Standard? I´m really interested in this subject, but I can´t find this magazine in Sweden. I have contacted QEX, but it is very difficult to buy back-issues. Have any one built this frequency standard and can tell me more about the project? You can access the source code for the project here: http://www.arrl.org/files/file/QEX%20Binaries/2013/November_13/11x13_Kaune_PIC_Code.zip /Anders ___ 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] Using GPS to Fine Tune a Rubidium Frequency Standard.
George wrote: I do not subscribe to QEX, but I know that all of the ARRL periodicals for 2013 (QST, NCJ and QEX) are on one CD and it is available now from ARRL http://www.arrl.org/shop/ARRL-Periodicals-DVD-2013 Best regards, Charles ___ 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] Using GPS to Fine Tune a Rubidium Frequency Standard.
Hi Anders, You can buy the 2013 QST CD-ROM from ARRL which includes QEX. I'm in the UK and have this CD, international delivery was no problem. Cost was $25, see http://www.arrl.org/shop/ARRL-Periodicals-DVD-2013/ The disk is well worth the cost. I've not built the project but have looked at the article. It references the Shera design and is basically a Trimble Resoluton T to LPRO101 GPSDO. It divides the 10MHz to 100kHz before comparison. I'm not qualified to comment on how good the design is, but you can contact me off-list if you want more details. Robert G8RPI. From: Anders Time anderst...@gmail.com To: time-nuts@febo.com Sent: Friday, 21 March 2014, 13:20 Subject: [time-nuts] Using GPS to Fine Tune a Rubidium Frequency Standard. Does anyone have a copy of the QEX 2013 november article(Bill Kaune) Using GPS to Fine Tune a Rubidium Frequency Standard? I´m really interested in this subject, but I can´t find this magazine in Sweden. I have contacted QEX, but it is very difficult to buy back-issues. Have any one built this frequency standard and can tell me more about the project? You can access the source code for the project here: http://www.arrl.org/files/file/QEX%20Binaries/2013/November_13/11x13_Kaune_PIC_Code.zip /Anders ___ 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] Using GPS to Fine Tune a Rubidium Frequency Standard.
I'm working on doing exactly this right now. There is a ton of information on how to build a GPSDO where the oscillator is an OCXO. But it is almost exactly the same thing to build a GPSDRbThe only change is that rather then sending a command to control a DAC that in turn controls the OCXO's EFC pin you send data to control the Rb.Also of course use some different constants. There seem to be two different class of Rb. One takes an EFC just like the OCXO so the controller looks just like a GPSDO and the other class of Rb accepts serial commends to adjust the frequency. These have an internal DAC. But either way the logic is the same. On Fri, Mar 21, 2014 at 6:20 AM, Anders Time anderst...@gmail.com wrote: Does anyone have a copy of the QEX 2013 november article(Bill Kaune) Using GPS to Fine Tune a Rubidium Frequency Standard? I´m really interested in this subject, but I can´t find this magazine in Sweden. I have contacted QEX, but it is very difficult to buy back-issues. Have any one built this frequency standard and can tell me more about the project? You can access the source code for the project here: http://www.arrl.org/files/file/QEX%20Binaries/2013/November_13/11x13_Kaune_PIC_Code.zip /Anders ___ 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] Using GPS to Fine Tune a Rubidium Frequency Standard.
Quite a few time nuts have Rb GPSDRb's running using Shera's controller. I did mine in 1999 with the help of Brooks and Corby and my first FRK died on Shrea's controller after 24 years of service. Bad lamp. Have to measure C field sensitivity just like on an OCXO and increasing sample time from 30 seconds to 120 helps. Works great. My first OCXO was last year using a MV89 when we worked on the release of Brooks last controller. Bert Kehren In a message dated 3/21/2014 2:31:45 P.M. Eastern Daylight Time, albertson.ch...@gmail.com writes: I'm working on doing exactly this right now. There is a ton of information on how to build a GPSDO where the oscillator is an OCXO. But it is almost exactly the same thing to build a GPSDRb The only change is that rather then sending a command to control a DAC that in turn controls the OCXO's EFC pin you send data to control the Rb.Also of course use some different constants. There seem to be two different class of Rb. One takes an EFC just like the OCXO so the controller looks just like a GPSDO and the other class of Rb accepts serial commends to adjust the frequency. These have an internal DAC. But either way the logic is the same. On Fri, Mar 21, 2014 at 6:20 AM, Anders Time anderst...@gmail.com wrote: Does anyone have a copy of the QEX 2013 november article(Bill Kaune) Using GPS to Fine Tune a Rubidium Frequency Standard? I´m really interested in this subject, but I can´t find this magazine in Sweden. I have contacted QEX, but it is very difficult to buy back-issues. Have any one built this frequency standard and can tell me more about the project? You can access the source code for the project here: http://www.arrl.org/files/file/QEX%20Binaries/2013/November_13/11x13_Kaune_PIC_Code.zip /Anders ___ 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. ___ 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] Using GPS to Fine Tune a Rubidium Frequency Standard.
Chris, Not to often I can offer useful advice. But I know others on time-nuts have experimented with the digital dacs in the RBs. There was program quite a while ago that let you tweak them. Essentially it seems you can not get them exactly on because of the DAC step function. Granted they are crazy close, but this is time-nuts. Regards Paul. WB8TSL On Fri, Mar 21, 2014 at 2:24 PM, Chris Albertson albertson.ch...@gmail.comwrote: I'm working on doing exactly this right now. There is a ton of information on how to build a GPSDO where the oscillator is an OCXO. But it is almost exactly the same thing to build a GPSDRbThe only change is that rather then sending a command to control a DAC that in turn controls the OCXO's EFC pin you send data to control the Rb.Also of course use some different constants. There seem to be two different class of Rb. One takes an EFC just like the OCXO so the controller looks just like a GPSDO and the other class of Rb accepts serial commends to adjust the frequency. These have an internal DAC. But either way the logic is the same. On Fri, Mar 21, 2014 at 6:20 AM, Anders Time anderst...@gmail.com wrote: Does anyone have a copy of the QEX 2013 november article(Bill Kaune) Using GPS to Fine Tune a Rubidium Frequency Standard? I´m really interested in this subject, but I can´t find this magazine in Sweden. I have contacted QEX, but it is very difficult to buy back-issues. Have any one built this frequency standard and can tell me more about the project? You can access the source code for the project here: http://www.arrl.org/files/file/QEX%20Binaries/2013/November_13/11x13_Kaune_PIC_Code.zip /Anders ___ 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. ___ 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] Using GPS to Fine Tune a Rubidium Frequency Standard.
Depends on what you call close. 1 E-14 steps are very doable. That does not mean that that is the accuracy because once you go below 1 E-12 you have to worry about barometric pressure and humidity assuming you already have temperature control. Bert In a message dated 3/21/2014 2:58:32 P.M. Eastern Daylight Time, paulsw...@gmail.com writes: Chris, Not to often I can offer useful advice. But I know others on time-nuts have experimented with the digital dacs in the RBs. There was program quite a while ago that let you tweak them. Essentially it seems you can not get them exactly on because of the DAC step function. Granted they are crazy close, but this is time-nuts. Regards Paul. WB8TSL On Fri, Mar 21, 2014 at 2:24 PM, Chris Albertson albertson.ch...@gmail.comwrote: I'm working on doing exactly this right now. There is a ton of information on how to build a GPSDO where the oscillator is an OCXO. But it is almost exactly the same thing to build a GPSDRb The only change is that rather then sending a command to control a DAC that in turn controls the OCXO's EFC pin you send data to control the Rb.Also of course use some different constants. There seem to be two different class of Rb. One takes an EFC just like the OCXO so the controller looks just like a GPSDO and the other class of Rb accepts serial commends to adjust the frequency. These have an internal DAC. But either way the logic is the same. On Fri, Mar 21, 2014 at 6:20 AM, Anders Time anderst...@gmail.com wrote: Does anyone have a copy of the QEX 2013 november article(Bill Kaune) Using GPS to Fine Tune a Rubidium Frequency Standard? I´m really interested in this subject, but I can´t find this magazine in Sweden. I have contacted QEX, but it is very difficult to buy back-issues. Have any one built this frequency standard and can tell me more about the project? You can access the source code for the project here: http://www.arrl.org/files/file/QEX%20Binaries/2013/November_13/11x13_Kaune_PIC_Code.zip /Anders ___ 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. ___ 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] Using GPS to Fine Tune a Rubidium Frequency Standard.
albertson.ch...@gmail.com said: There seem to be two different class of Rb. One takes an EFC just like the OCXO so the controller looks just like a GPSDO and the other class of Rb accepts serial commends to adjust the frequency. These have an internal DAC. But either way the logic is the same. Is it a DAC or DDS chip? Has anybody looked at the spectrum? -- 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] Using GPS to Fine Tune a Rubidium Frequency Standard.
Some use DAC's some use DDS' the FE 5680 uses a DDS. Bert Kehren In a message dated 3/21/2014 3:17:12 P.M. Eastern Daylight Time, hmur...@megapathdsl.net writes: albertson.ch...@gmail.com said: There seem to be two different class of Rb. One takes an EFC just like the OCXO so the controller looks just like a GPSDO and the other class of Rb accepts serial commends to adjust the frequency. These have an internal DAC. But either way the logic is the same. Is it a DAC or DDS chip? Has anybody looked at the spectrum? -- 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] Using GPS to Fine Tune a Rubidium Frequency Standard.
Hal Actually now that you mention it was the DDS chip. Bert I agree with your comments. How tight can it be. Thanks On Fri, Mar 21, 2014 at 3:13 PM, Hal Murray hmur...@megapathdsl.net wrote: albertson.ch...@gmail.com said: There seem to be two different class of Rb. One takes an EFC just like the OCXO so the controller looks just like a GPSDO and the other class of Rb accepts serial commends to adjust the frequency. These have an internal DAC. But either way the logic is the same. Is it a DAC or DDS chip? Has anybody looked at the spectrum? -- 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.
[time-nuts] Nav Receiver Sawtooth Correction?
I've gotten my PLL mostly working, but, since I'm using a nav receiver, it looks like I may want to see if I can do a poor-man's sawtooth correction based on GPS position changes. Has anyone done this or have a reference for a project that has? It would seem to me that only the East-West movements would be a factor, but I dunno. As a beginning, I was just going to plot lat and lon deltas from gpsd data to see what correlates to the phase error jumps I'm seeing, unless this path has already been tread. I don't expect the accuracy that would be afforded by a real timing receiver. 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.
Re: [time-nuts] Using GPS to Fine Tune a Rubidium Frequency Standard.
Paul Do not understand your question, what do you mean with tight? Bert Kehren In a message dated 3/21/2014 3:22:41 P.M. Eastern Daylight Time, paulsw...@gmail.com writes: Hal Actually now that you mention it was the DDS chip. Bert I agree with your comments. How tight can it be. Thanks On Fri, Mar 21, 2014 at 3:13 PM, Hal Murray hmur...@megapathdsl.net wrote: albertson.ch...@gmail.com said: There seem to be two different class of Rb. One takes an EFC just like the OCXO so the controller looks just like a GPSDO and the other class of Rb accepts serial commends to adjust the frequency. These have an internal DAC. But either way the logic is the same. Is it a DAC or DDS chip? Has anybody looked at the spectrum? -- 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. ___ 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] Using GPS to Fine Tune a Rubidium Frequency Standard.
accurate On Fri, Mar 21, 2014 at 3:51 PM, ewkeh...@aol.com wrote: Paul Do not understand your question, what do you mean with tight? Bert Kehren In a message dated 3/21/2014 3:22:41 P.M. Eastern Daylight Time, paulsw...@gmail.com writes: Hal Actually now that you mention it was the DDS chip. Bert I agree with your comments. How tight can it be. Thanks On Fri, Mar 21, 2014 at 3:13 PM, Hal Murray hmur...@megapathdsl.net wrote: albertson.ch...@gmail.com said: There seem to be two different class of Rb. One takes an EFC just like the OCXO so the controller looks just like a GPSDO and the other class of Rb accepts serial commends to adjust the frequency. These have an internal DAC. But either way the logic is the same. Is it a DAC or DDS chip? Has anybody looked at the spectrum? -- 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. ___ 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] Using GPS to Fine Tune a Rubidium Frequency Standard.
What he is asking is if the Rb's frequency adjustments are done with a DAC or a DDS. And how fine the steps are. My answer is I don't care. If my goal were to build the best frequency reference then I'd seriously shop around for the best oscillator but my goal is not that. It is to to get the best trim setting I can get for the existing equipment. I suspect my $40 FE-5680A is not the best On Fri, Mar 21, 2014 at 12:51 PM, ewkeh...@aol.com wrote: Paul Do not understand your question, what do you mean with tight? Bert Kehren In a message dated 3/21/2014 3:22:41 P.M. Eastern Daylight Time, paulsw...@gmail.com writes: Hal Actually now that you mention it was the DDS chip. Bert I agree with your comments. How tight can it be. Thanks On Fri, Mar 21, 2014 at 3:13 PM, Hal Murray hmur...@megapathdsl.net wrote: albertson.ch...@gmail.com said: There seem to be two different class of Rb. One takes an EFC just like the OCXO so the controller looks just like a GPSDO and the other class of Rb accepts serial commends to adjust the frequency. These have an internal DAC. But either way the logic is the same. Is it a DAC or DDS chip? Has anybody looked at the spectrum? -- 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. ___ 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] GPSDO simulation tool
Well done! Don On 03/21/2014 03:55 PM, Tom Van Baak wrote: Designing a GPSDO is a permanent topic of time-nuts, and always invites lots of opinions and methods. The net performance of a microcontroller-based GPSDO is mostly due to the following ingredients: - the stability of the OCXO (or TCXO or Rb or whatever the LO is) - the stability of the GPS 1PPS (including sawtooth correction, or not) - the disciplining algorithm itself, and user-settable configuration parameters or filtering - the finite resolution of the TIC or phase comparator - the finite resolution of the DAC/EFC Normally what happens is that someone spends weeks or months or even years working on each of these ingredients, measuring, comparing, tweaking, or maybe just hoping for the best. These measurements can take a lot of time, or be difficult to replicate. I have an alternative. It's a simple software tool which takes *real* GPS phase data, and *real* LO phase data, and a *real* GPSDO algorithm(s) -- along with optional resolution of the TIC and optional resolution of the DAC -- and then creates GPSDO phase data through *simulation*. You can then plot this virtual GPSDO phase data with Stable32 or Plotter or TimeLab or your favorite phase / frequency / stability tool. So instead of waiting hours and days to test your new filtering idea, or your new GPSDO algorithm, or to compare the effect of a 10 ns vs. 1 ns vs. 100 ps vs. 10 ps TIC, or to compare the effect a 10-bit vs. 16-bit vs. 24-bit DAC -- you just run the simulation on your PC and get an answer in a few seconds. Have a look and let me know what you think. The tool is gpsim1.c (Windows: gpsim1.exe) under: http://www.leapsecond.com/tools/ For this to work, one needs actual GPS data and actual LO data. I have a growing collection of sample data files here: http://www.leapsecond.com/pages/gpsdo-sim/ For example, if you run this command: gpsim1 gps-mtk3339.txt ocxo.dat gpsdo.txt and use TimeLab to plot these three files, you will get the attached plot. No solder, no instruments, no antenna, no waiting, no guessing. A complete 4-day simulation takes just 3 seconds (on my 10-year old laptop). Load the simulated phase data with 'L' in TimeLab and view phase, frequency, ADEV, MDEV, TDEV. Answer your GPSDO design questions in minutes instead of weeks. Try different parameters. Try different GPS boards. Try different oscillators. See if you can make the best ADEV. Try new disciplining algorithms. Make the PID more complex. Change the filtering. /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. ___ 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] Great video -- U.S. Naval Observatory
Dr. Demetrios Matsakis, Chief Scientist for USNO's Time Services, gives a tour http://vimeo.com/87871443 http://vimeo.com/87871443 ___ 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] GPSDO simulation tool
Monumental... On Sat, Mar 22, 2014 at 12:25 AM, djl d...@montana.com wrote: Well done! Don On 03/21/2014 03:55 PM, Tom Van Baak wrote: Designing a GPSDO is a permanent topic of time-nuts, and always invites lots of opinions and methods. The net performance of a microcontroller-based GPSDO is mostly due to the following ingredients: - the stability of the OCXO (or TCXO or Rb or whatever the LO is) - the stability of the GPS 1PPS (including sawtooth correction, or not) - the disciplining algorithm itself, and user-settable configuration parameters or filtering - the finite resolution of the TIC or phase comparator - the finite resolution of the DAC/EFC Normally what happens is that someone spends weeks or months or even years working on each of these ingredients, measuring, comparing, tweaking, or maybe just hoping for the best. These measurements can take a lot of time, or be difficult to replicate. I have an alternative. It's a simple software tool which takes *real* GPS phase data, and *real* LO phase data, and a *real* GPSDO algorithm(s) -- along with optional resolution of the TIC and optional resolution of the DAC -- and then creates GPSDO phase data through *simulation*. You can then plot this virtual GPSDO phase data with Stable32 or Plotter or TimeLab or your favorite phase / frequency / stability tool. So instead of waiting hours and days to test your new filtering idea, or your new GPSDO algorithm, or to compare the effect of a 10 ns vs. 1 ns vs. 100 ps vs. 10 ps TIC, or to compare the effect a 10-bit vs. 16-bit vs. 24-bit DAC -- you just run the simulation on your PC and get an answer in a few seconds. Have a look and let me know what you think. The tool is gpsim1.c (Windows: gpsim1.exe) under: http://www.leapsecond.com/tools/ For this to work, one needs actual GPS data and actual LO data. I have a growing collection of sample data files here: http://www.leapsecond.com/pages/gpsdo-sim/ For example, if you run this command: gpsim1 gps-mtk3339.txt ocxo.dat gpsdo.txt and use TimeLab to plot these three files, you will get the attached plot. No solder, no instruments, no antenna, no waiting, no guessing. A complete 4-day simulation takes just 3 seconds (on my 10-year old laptop). Load the simulated phase data with 'L' in TimeLab and view phase, frequency, ADEV, MDEV, TDEV. Answer your GPSDO design questions in minutes instead of weeks. Try different parameters. Try different GPS boards. Try different oscillators. See if you can make the best ADEV. Try new disciplining algorithms. Make the PID more complex. Change the filtering. /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. ___ 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] GPSDO simulation tool
What's the best way to make an ADEV plot, other then using time lab? Timelab appears to be an MS Windows .exe file.I could write a script based on the definition of adev but I bet someone has already done this. On Fri, Mar 21, 2014 at 4:25 PM, djl d...@montana.com wrote: Well done! Don On 03/21/2014 03:55 PM, Tom Van Baak wrote: Designing a GPSDO is a permanent topic of time-nuts, and always invites lots of opinions and methods. The net performance of a microcontroller-based GPSDO is mostly due to the following ingredients: - the stability of the OCXO (or TCXO or Rb or whatever the LO is) - the stability of the GPS 1PPS (including sawtooth correction, or not) - the disciplining algorithm itself, and user-settable configuration parameters or filtering - the finite resolution of the TIC or phase comparator - the finite resolution of the DAC/EFC Normally what happens is that someone spends weeks or months or even years working on each of these ingredients, measuring, comparing, tweaking, or maybe just hoping for the best. These measurements can take a lot of time, or be difficult to replicate. I have an alternative. It's a simple software tool which takes *real* GPS phase data, and *real* LO phase data, and a *real* GPSDO algorithm(s) -- along with optional resolution of the TIC and optional resolution of the DAC -- and then creates GPSDO phase data through *simulation*. You can then plot this virtual GPSDO phase data with Stable32 or Plotter or TimeLab or your favorite phase / frequency / stability tool. So instead of waiting hours and days to test your new filtering idea, or your new GPSDO algorithm, or to compare the effect of a 10 ns vs. 1 ns vs. 100 ps vs. 10 ps TIC, or to compare the effect a 10-bit vs. 16-bit vs. 24-bit DAC -- you just run the simulation on your PC and get an answer in a few seconds. Have a look and let me know what you think. The tool is gpsim1.c (Windows: gpsim1.exe) under: http://www.leapsecond.com/tools/ For this to work, one needs actual GPS data and actual LO data. I have a growing collection of sample data files here: http://www.leapsecond.com/pages/gpsdo-sim/ For example, if you run this command: gpsim1 gps-mtk3339.txt ocxo.dat gpsdo.txt and use TimeLab to plot these three files, you will get the attached plot. No solder, no instruments, no antenna, no waiting, no guessing. A complete 4-day simulation takes just 3 seconds (on my 10-year old laptop). Load the simulated phase data with 'L' in TimeLab and view phase, frequency, ADEV, MDEV, TDEV. Answer your GPSDO design questions in minutes instead of weeks. Try different parameters. Try different GPS boards. Try different oscillators. See if you can make the best ADEV. Try new disciplining algorithms. Make the PID more complex. Change the filtering. /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. ___ 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] Aircraft ping timing
On Thu, 20 Mar 2014 14:42:42 -0400 Joe Leikhim jleik...@leikhim.com wrote: I just red somewhere that the last ping was the only one recorded by Inmarsat system, Pings up to that point were presumed to occur due to known reporting intervals. So there is no track. The Inmarsat data is a red herring. The plane could have ditched into the water 85 minutes after the incident:, at location near last radar contact and floated with Inmarsat operating on service battery for hours. The ELT's used in this aircraft have been implicated in two fires due to shorted lithium battery wires. There was an AD/Recall issued. No reports whatsoever about the ELT being activated, so if it burned.. Good only for 48 hours or so anyway if looking in the wrong place. Maybe there is a market for Orbcomm asset tracking transmitters mounted way up in an inaccessible location of the tail with own back up battery supply. Orbcomm is kind of troublesome. There is a tracking service used mostly by helicopters, which of course are notorious for falling off the radar due to low altitude. It is Iridium based. http://us.spidertracks.com/ I've used or have know users various satellite messaging services over the years. Iridium is good. I was a Globcomm customer, but it was not reliable. A friend was on Orbcomm and it had issues as well. ___ 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] Aircraft ping timing
In retrospect it is kind of crazy that fleet owners will put tracking devices on $100K semi trucks and cranes yet $100 million aircraft have to rely upon 60 year old technology (Transponders) and ACARS to keep track of them. I don't question the utility of TCAS and Transponders, it is just the issue of not tracking such a valuable asset that is kind of crazy. Can you imagine how much an aircraft like that is worth in spare parts alone? -on the world market. If I were an insurer I would be asking questions of the industry. Orbcomm is kind of troublesome. There is a tracking service used mostly by helicopters, which of course are notorious for falling off the radar due to low altitude. It is Iridium based. http://us.spidertracks.com/ I've used or have know users various satellite messaging services over the years. Iridium is good. I was a Globcomm customer, but it was not reliable. A friend was on Orbcomm and it had issues as well. -- Joe Leikhim Leikhim and Associates Communications Consultants Oviedo, Florida jleik...@leikhim.com 407-982-0446 WWW.LEIKHIM.COM ___ 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.
