Re: [time-nuts] Comparing the performance of 17 different GPSDOs
Hi At least the HP boxes run through a series of filter settings and do a pretty good job of handling the “lack” of SA. The one thing that is very apparent in the TDEV data on the 3801 is the lack of sawtooth correction. I suppose you could call that a SA optimization that no longer is on the “good idea” list. Bob > On Dec 9, 2018, at 5:13 PM, Poul-Henning Kamp wrote: > > > In message , "Tom Van Baak" writes: >>> Tom is currently working his magic on the raw data captures with Timelab. >>> The results so far are looking very good and much more informative. >> >> Mark's experiment was nicely done. Here's the first set of TimeLab plots: >> >> http://leapsecond.com/u/sims/gpsdo17/ >> >> If that's too much, just look at the last 2 or 4 plots on that page, >> arranged by worse than average and better than average. >> I'll fix a couple of typos and add missing data for two of the GPSDO. > > I wonder how many of these still run with SA optimized PLL time constants ? > > > -- > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > p...@freebsd.org | TCP/IP since RFC 956 > FreeBSD committer | BSD since 4.3-tahoe > Never attribute to malice what can adequately be explained by incompetence. > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Comparing the performance of 17 different GPSDOs
Is this before or after filtering Bert Kehren In a message dated 12/9/2018 5:14:32 PM Eastern Standard Time, p...@phk.freebsd.dk writes: In message , "Tom Van Baak" writes: >> Tom is currently working his magic on the raw data captures with Timelab. >> The results so far are looking very good and much more informative. > >Mark's experiment was nicely done. Here's the first set of TimeLab plots: > >http://leapsecond.com/u/sims/gpsdo17/ > >If that's too much, just look at the last 2 or 4 plots on that page, arranged >by worse than average and better than average. >I'll fix a couple of typos and add missing data for two of the GPSDO. I wonder how many of these still run with SA optimized PLL time constants ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Comparing the performance of 17 different GPSDOs
In message , "Tom Van Baak" writes: >> Tom is currently working his magic on the raw data captures with Timelab. >> The results so far are looking very good and much more informative. > >Mark's experiment was nicely done. Here's the first set of TimeLab plots: > >http://leapsecond.com/u/sims/gpsdo17/ > >If that's too much, just look at the last 2 or 4 plots on that page, arranged >by worse than average and better than average. >I'll fix a couple of typos and add missing data for two of the GPSDO. I wonder how many of these still run with SA optimized PLL time constants ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Comparing the performance of 17 different GPSDOs
> Tom is currently working his magic on the raw data captures with Timelab. > The results so far are looking very good and much more informative. Mark's experiment was nicely done. Here's the first set of TimeLab plots: http://leapsecond.com/u/sims/gpsdo17/ If that's too much, just look at the last 2 or 4 plots on that page, arranged by worse than average and better than average. I'll fix a couple of typos and add missing data for two of the GPSDO. /tvb ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Comparing the performance of 17 different GPSDOs
Hi Mark, First of all, congratulation on good work, as always. I think the way of presenting it makes it somewhat hard to get an overview. I think you should do a proper paper on it. This would have been interesting to have as a paper for IFCS/EFTF. Cut-off date passed. It would be nice with a table listing performance for a couple of key taus. The one thing that I wonder is how much localization error of the receivers can be judged to have effected their performance. If they where not fed the same position, some deviation may be to how well they averaged in a fixed location, which may vary from time to time and that other processes od the receiver where overshadowed by how well they where located. Cheers, Magnus On 12/9/18 6:10 AM, Mark Sims wrote: > I recently completed some comparison tests of the PPS and 10 MHz outputs of > 17 different GPSDOs. > > The tests were done with a TAPR TICC time interval counter running in > timestamp mode and the data was acquired and processed with Lady Heather. > The TICC was clocked by a HP-5071A cesium beam oscillator with the > high-performance tube. The TICC has a resolution of around 60 picoseconds. > > The PPS signal from the GPSDO was connected to channel A of the TICC (for > those GPSDOs that have an easily accessible PPS signal). For receivers > without a PPS signal available, Heather shows ADEV, HDEV, MDEV, and TDEV data > for the 10 MHz signal. For receivers with a PPS, ADEV is shown for the > 1PPS and 10 MHz signals. > > The GPSDO output frequency (10 MHZ) was connected to channel B of the TICC > through a TAPR TADD-2 Mini divider to get a 1 Hz output. > > Note that PPS and 10 MHz plots have a display averaging filter applied. > Without this filter the plots mostly show noisy "grass" and not any > interesting details. A side effect of the display filter is to reduce the > "span" (difference between the max and min values seen) of the plot data. > Typically the unfiltered spans are around twice the value shown in the plot > header, but for a couple of receivers it is up to a 10x reduction of the raw > span. > > Each GPSDO was allowed to warm up for at least 24 hours, or longer... until > the DAC output voltage slope leveled off. > > The GPSDO antenna was a L1/L2/GPS/GLONASS/BEIDOU antenna from China. With a > L1/L2 survey receiver this antenna produces location error ellipse in the > 5-10mm range. It is mounted on a 1 meter tripod and fed into an 8-way > amplified L1/L2/Glonass/Beidou splitter. The antenna is in a rather horrible > location for multi-path and sky view. Lots of tall trees and a 2 story > stucco-over-wire mesh house. > > http://www.eevblog.com/forum/metrology/comparing-the-performance-of-17-different-gpsdos/msg2025295/#msg2025295 > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Comparing the performance of 17 different GPSDOs
Hi Mark, good job. Have you made an analysis of the results and made some considerations about the parameters you have measured? Luciano Da "time-nuts" time-nuts-boun...@lists.febo.com A "time-nuts@lists.febo.com" time-nuts@lists.febo.com Cc Data Sun, 9 Dec 2018 05:10:17 +0000 Oggetto [time-nuts] Comparing the performance of 17 different GPSDOs I recently completed some comparison tests of the PPS and 10 MHz outputs of 17 different GPSDOs. The tests were done with a TAPR TICC time interval counter running in timestamp mode and the data was acquired and processed with Lady Heather. The TICC was clocked by a HP-5071A cesium beam oscillator with the high-performance tube. The TICC has a resolution of around 60 picoseconds. The PPS signal from the GPSDO was connected to channel A of the TICC (for those GPSDOs that have an easily accessible PPS signal). For receivers without a PPS signal available, Heather shows ADEV, HDEV, MDEV, and TDEV data for the 10 MHz signal. For receivers with a PPS, ADEV is shown for the 1PPS and 10 MHz signals. The GPSDO output frequency (10 MHZ) was connected to channel B of the TICC through a TAPR TADD-2 Mini divider to get a 1 Hz output. Note that PPS and 10 MHz plots have a display averaging filter applied. Without this filter the plots mostly show noisy "grass" and not any interesting details. A side effect of the display filter is to reduce the "span" (difference between the max and min values seen) of the plot data. Typically the unfiltered spans are around twice the value shown in the plot header, but for a couple of receivers it is up to a 10x reduction of the raw span. Each GPSDO was allowed to warm up for at least 24 hours, or longer... until the DAC output voltage slope leveled off. The GPSDO antenna was a L1/L2/GPS/GLONASS/BEIDOU antenna from China. With a L1/L2 survey receiver this antenna produces location error ellipse in the 5-10mm range. It is mounted on a 1 meter tripod and fed into an 8-way amplified L1/L2/Glonass/Beidou splitter. The antenna is in a rather horrible location for multi-path and sky view. Lots of tall trees and a 2 story stucco-over-wire mesh house. http://www.eevblog.com/forum/metrology/comparing-the-performance-of-17-different-gpsdos/msg2025295/#msg2025295 ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Comparing the performance of 17 different GPSDOs
I recently completed some comparison tests of the PPS and 10 MHz outputs of 17 different GPSDOs. The tests were done with a TAPR TICC time interval counter running in timestamp mode and the data was acquired and processed with Lady Heather. The TICC was clocked by a HP-5071A cesium beam oscillator with the high-performance tube. The TICC has a resolution of around 60 picoseconds. The PPS signal from the GPSDO was connected to channel A of the TICC (for those GPSDOs that have an easily accessible PPS signal). For receivers without a PPS signal available, Heather shows ADEV, HDEV, MDEV, and TDEV data for the 10 MHz signal. For receivers with a PPS, ADEV is shown for the 1PPS and 10 MHz signals. The GPSDO output frequency (10 MHZ) was connected to channel B of the TICC through a TAPR TADD-2 Mini divider to get a 1 Hz output. Note that PPS and 10 MHz plots have a display averaging filter applied. Without this filter the plots mostly show noisy "grass" and not any interesting details. A side effect of the display filter is to reduce the "span" (difference between the max and min values seen) of the plot data. Typically the unfiltered spans are around twice the value shown in the plot header, but for a couple of receivers it is up to a 10x reduction of the raw span. Each GPSDO was allowed to warm up for at least 24 hours, or longer... until the DAC output voltage slope leveled off. The GPSDO antenna was a L1/L2/GPS/GLONASS/BEIDOU antenna from China. With a L1/L2 survey receiver this antenna produces location error ellipse in the 5-10mm range. It is mounted on a 1 meter tripod and fed into an 8-way amplified L1/L2/Glonass/Beidou splitter. The antenna is in a rather horrible location for multi-path and sky view. Lots of tall trees and a 2 story stucco-over-wire mesh house. http://www.eevblog.com/forum/metrology/comparing-the-performance-of-17-different-gpsdos/msg2025295/#msg2025295 ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
