[time-nuts] GPS message jitter (preliminary results)

[Mark Sims]

I ran some tests on the message timing of some V.KEL gps receivers in both NMEA and binary mode.  These receivers are the cheapest ones I have (3 for $15 - $20, shipped).   They use a SIRF III chip and have an on-board ceramic patch antenna.  They performed amazingly well.  No problems tracking sats indoors in a very poor location.   Message jitter was less than 20 msecs peak-peak,  standard deviation less than 2 milliseconds.   ADEVs at tau 10000 after an overnight run in NMEA mode (hardware serial port) were in the 1E-7 range!    They also have a 1PPS signal on the connector so no need to go digging for a place to bodge on a wire like with some of the other cheap GPS modules out there.   

V.KEL also makes a Ublox based version of the module (around $22 for one)... mine reports that it has a Ublox 7 chip, though V.KEL's part number implies that it a Ublox 6.