I have verified the Skytraq claim on my stand alone NS-T. Tue Jan 27 06:52:06 UTC 2015 $GPGGA,065206.000,4847.3506,N,00216.3005,E,1,06,1.3,191.0,M,47.0,M,,0000*59 Tue Jan 27 06:52:06 UTC 2015 $GPGLL,4847.3506,N,00216.3005,E,065206.000,A,A*52 Tue Jan 27 06:52:06 UTC 2015 $GPGSA,A,3,04,01,22,28,27,11,,,,,,,2.1,1.3,1.7*3F Tue Jan 27 06:52:06 UTC 2015 $GPGSV,2,1,07,04,83,016,40,11,77,287,36,01,57,288,47,28,29,299,42*7E Tue Jan 27 06:52:06 UTC 2015 $GPGSV,2,2,07,03,28,223,09,22,25,056,41,27,21,149,26*42 Tue Jan 27 06:52:06 UTC 2015 $GPRMC,065206.000,A,4847.3506,N,00216.3005,E,000.0,000.0,270115,,,A*65 Tue Jan 27 06:52:06 UTC 2015 $GPVTG,000.0,T,,M,000.0,N,000.0,K,A*0D Tue Jan 27 06:52:06 UTC 2015 $GPZDA,065206.000,27,01,2015,00,00*53
Using the GNSS gui, Query Timing, get a NAK. Monitoring 1PPS gets blank. When booting from Flash, the quantization error of +/-6ns was verifiable both with Monitor Timing on the GUI and on my scope triggered from my T-Bolt.. When booting from ROM it doesn’t seem to be any worse than +/-10ns . I would think that the lower quantization error would enable better phase locking in a GPSDO, especially with a long time constant, which is why I bought the device in the first place. So anyone with an LTE-Lite may just prefer to not use the NMEA stream until a new firmware becomes available, rather than use the WA. It would be of interest to others to see what booting from ROM makes in practice with the LTE-Lite. One observation that I will make is that TTFF is MUCH faster when booting from ROM, and the device is MUCH more sensitive. I can pull in twice the number of SATS when booting from ROM. I am getting HDOP figure <1…wow! The reason why my receiver is not glued to a PRS10 at the moment is that I kept losing 3D Position fix according to the GUI when booted from Flash, even though when in Static mode the 1PPS looked good. "Ceux qui sont prêts à abandonner une liberté essentielle pour obtenir une petite et provisoire sécurité, ne méritent ni liberté ni sécurité." Benjimin Franklin > Le 27 janv. 2015 à 02:29, Bill Beam <wb...@gci.net> a écrit : > > Be careful with 'eyeball data'. GPS receiver does not generate NMEA time > data and the leading edge of PPS at the same time. > Programs like Tac32 (totally accurate clock) and Lady Heather increment the > time display at the leading edge of PPS with a > value 1 second greater than the previous NMEA data time. > > I am able to run multiple GPS receivers into multiple computers running > Tac32. The LTE-lite displays one second earlier than > all the others. > > Prior to the announcement of "Leap Second Pending" in the GPS data stream the > LTE-lite agreed with all other units. Now it does not. > > On Mon, 26 Jan 2015 22:59:36 +0100, Mike Cook wrote: > >> Yes there is certainly an error here: >> With my timing module I was just eyeballing the output on a windows platform >> , comparing GUI data. >> I have just linked the module up to a BeagleBone Black syncG�d with NTP and >> this is the NMEA msg log: > >> root@bb3:/home/mike/serial-ports# while read GGA; do echo `date` $GGA; done >> < /dev/ttyO4 >> Mon Jan 26 21:51:07 UTC 2015 >> $GPGGA,215106.000,4847.3526,N,00216.3005,E,1,04,2.8,192.8,M,47.0,M,,0000*5C >> Mon Jan 26 21:51:07 UTC 2015 >> $GPGLL,4847.3526,N,00216.3005,E,215106.000,A,A*56 >> Mon Jan 26 21:51:07 UTC 2015 $GPGSA,A,3,25,12,06,31,,,,,,,,,3.0,2.8,1.0*3A >> Mon Jan 26 21:51:07 UTC 2015 >> $GPRMC,215106.000,A,4847.3526,N,00216.3005,E,000.0,173.5,260115,,,A*60 >> Mon Jan 26 21:51:07 UTC 2015 $GPVTG,173.5,T,,M,000.0,N,000.0,K,A*0D >> Mon Jan 26 21:51:07 UTC 2015 $GPZDA,215106.000,26,01,2015,00,00*54 >> Mon Jan 26 21:51:07 UTC 2015 $PSTI,00,2,0,4.6,,*30 > > snip > >> The time data is all a second late so they appear to have a serious issue. > >>> Le 26 janv. 2015 +� 02:47, Bill Beam <wb...@gci.net> a +�crit : > > snip > >>> Odd indeed. My LTE-lite is one second late, appears to have already added >>> the pending leap second. >>> I can compare with four other GPS timeing receivers using time pulse on DCD >>> line. The NMEA data >>> reports in error. > > snip > > > > Bill Beam > NL7F > > > > _______________________________________________ > 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.
