Hi Stephan. Your issue looks similar to one that has been previously reported. The Hardware Sustaining Engineering team is currently investigating.
Would it be possible for you to try powering the GPSDO module from a lab supply instead of plugging it in to the N210 motherboard and checking if your issue still persists? That would help us determine if you are experiencing the same problem. Another helpful measurement would be to measure the voltage drop of the 6V wall wart when the GPSDO IS powered by the N210 motherboard. We will keep you and list updated on the progress of the investigation. -Robin On Fri, Nov 9, 2018 at 3:06 AM Stephan Esterhuizen via USRP-users < usrp-users@lists.ettus.com> wrote: > Hi All, > > I have two N200 USRPs with Jackson-Labs Firefly 1A GPSDO. I'm doing a very > basic test, where I have a common active GPS antenna split 2 ways (with DC > block on one N200 GPS antenna port). I then watch the 1PPS from each GPSDO > on a scope, and unfortunately see the PPS drift by as much as 14 > microseconds per second relative to each other. When this offset reaches > about 1.5-2.0 milliseconds, I see the PPS relative offset "snap" down to a > few micro seconds error, but then they immediately start drifting apart > again. > > The N200 GPSDO reports they're locked. I wrote some quick python code to > query sensors: > > ---------------------- > FIRST N200: > ---------------------- > [INFO] [GPS] Found an internal GPSDO: Jackson-Labs, FireFly , Firmware Rev > 0.929 > [INFO] [USRP2] Setting references to the internal GPSDO > GPS lock status: locked > GPS_GPGGA: > $GPGGA,095011.00,xxxx.xxxxx,N,xxxx.xxxxx,E,1,10,0.9,320.7,M,46.9,M,,*6C > GPS_SERVO: 18-11-09 3888 94089 21.81 2.08E-11 13 10 6 0x0 > GPS epoch time: 1541757012 seconds > Ref: locked > > > ---------------------- > SECOND N200 > ---------------------- > > [INFO] [GPS] Found an internal GPSDO: Jackson-Labs, FireFly , Firmware Rev > 0.929 > [INFO] [USRP2] Setting references to the internal GPSDO > GPS lock status: locked > GPS_GPGGA: > $GPGGA,095027.00,xxxx.xxxxx,N,xxxx.xxxx,E,1,08,1.1,317.9,M,46.9,M,,*63 > GPS_SERVO: 18-11-09 2948 120000 796.02 9.59E-09 13 8 2 0x326 > GPS epoch time: 1541757029 seconds > Ref: locked > > ============ > > At this point, it might be a question for Jacksonlabs, since I'm not > really using any N200 functions except for reading back the Ublox GPS NMEA > strings. > > Has anyone seen this kind of behavior before? > > I'm suspecting the GPS_SERVO field might shed some light, but don't quite > know how to read it. > > Thanks for any pointers > > Stephan > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >
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