Hi > On Feb 13, 2019, at 1:49 PM, Achim Gratz <[email protected]> wrote: > > Bob kb8tq writes: >> It’s just like the other uBlox modules (and just like the F9T …) the >> external >> input is a once a second time stamper with an 8 ns resolution (just like the >> +/- 4 ns on the sawtooth ….). > > A minor nit: If it works as the M8 series does (which is very likely), > the timestamp facility gives you the last positive and the last negative > going transitions w.r.t. the configured message rate, plus the count of > positive going transistions. This means you can get both higher > timestamp rates by configuring a message rate of more than one per > second (which does have some other implications, though) and can use > (much) higher frequencies than just simply PPS (but get only the count + > measurement of the last transitions). Also, if the hardware doesn't use > the second EXTINT pin for something else (like power management), there > actually should be two of these timestamp inputs useable. > >> One would *guess* they are using the same >> free running / TCXO clock for both the PPS out and the timestamp coming in. > > It's not confirmed in any documentation that I've found, but the above > characteristic hints at the timestamp facility being some counters and > registers in hardware, so the system clock is the only thing that could > be used for this. On a proper timing module with FTS firmware you could > of course inject your own cleaned up clock to use as the timebase, plus > you can use it to discipline an external frequency source.
The uBlox gizmos have two onboard clock sources. There’s a TCXO and an RTC oscillator. The RTC is at typical low power / low frequency gizmo. The TCXO is the only thing in there that is good enough to generate the PPS or to do the time stamps ….. Bob > > Btw, if anybody is thinking about getting the ardusimple F9P-RTK module, > somewhere in their forum it is mentioned that a bug on the current board > revision has the PPS output at 0.7V instead of the documented 3.3V. > > > Regards, > Achim. > -- > +<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+ > > Factory and User Sound Singles for Waldorf Blofeld: > http://Synth.Stromeko.net/Downloads.html#WaldorfSounds > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
