PPS and GPS Modules for Timing/Oscillator Disipline

GPS/GNSS Development Boards
1

Can anyone tell me which of the GPS modules SparkFun sells actually support Pulse Per Second (PPS) output suitable for use in accurate timing and oscillator discipline applications?

I have encountered several data sheets which indicate that while a PPS pin is reserved, the firmware in a given unit may not support the function. I am not always certain that the data sheets I read are current or specific to the firmware revision of the units I am looking at.

This is not a problem that is peculiar to SF. I find this difficulty from many sources. Many user have no interest in precision timing applications. But I see that several do.

I am looking for a unit that is suitable for use at least as an Internet NTP source.

– Dave

2

I too have the same problem and it is proving remarkably difficult to source a unit over here in the UK. I recently acquired a Zycast SG-949 for the purpose as the specs told me it was very accurate however it lacks the 1PPS output I need. I am about to take it apart to see if there is an obvious connection on the PCB to take a feed from. Lets hope I don’t let the smoke out! Its based on the SiRF Start III Chipset so if anyone else has a clue on this please let me know.

It did occur to me that if I can communicate to the 949 in SiRF Binary mode it might be possible to extract the 1PPS pulse across the USB interface however this will more than likely disable the NMEA 183 data stream which I also need. Can anyone verify this?

BTW for anyone wanting a cheap (£33 inc P&P) weatherproof GPS mouse solution I can recommend the 949. I think it would be great for robotics. Probably cheaper in the US !

Regards

Steve

3

wittend:
Can anyone tell me which of the GPS modules SparkFun sells actually support Pulse Per Second (PPS) output suitable for use in accurate timing and oscillator discipline applications?

The ETek EB-85A and the Trimble Lassen iQ both have PPS output.

I just emailed support about this very thing. SparkFun needs to convince the OEMs to produce less-sucky modules. The last few time servers I built used ublox antaris4t or garmin gps18/lvc receivers.