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.
