[time-nuts] TruePosition on the Arduino

Mark Sims holrum at hotmail.com
Thu Jun 8 20:20:25 EDT 2017

Of all the GPS devices that Lady Heather supports,  only three send the time code before the 1PPS.  The last byte of the time code message arrives the indicated number of milliseconds from the PPS pulse:

Z38xx and related devices (including Lucent KS):  -965 ms
Lucent RFTG-m: -663 ms
Trimble SV6 in TAIP mode:  -175 ms

These are typical times.  The actual times may vary depending upon the operating system,  serial port drivers, receiver firmware.

The Jupiter-T family of receivers output the time code 1200 msecs AFTER the 1PPS.   They are the only receiver that I have seen that has a offset over 1 second.  Most devices are less than 300 msecs.


> Digging around further...I couldn't find a single GPS module that would 
put out the timecode before the 1PPS tick.

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