[ntp:questions] Linux NTPd using a older Trimble Thunderbolt GPS Receiver

Rob nomail at example.com
Tue Jan 20 12:34:14 UTC 2015

George Ross <gdmr at inf.ed.ac.uk> wrote:
> --===============2288611982837908707==
> Content-Type: multipart/signed; boundary="==_Exmh_1421754685_7720P";
> 	 micalg=pgp-sha1; protocol="application/pgp-signature"
> Content-Transfer-Encoding: 7bit
> --==_Exmh_1421754685_7720P
> Content-Type: text/plain; charset=us-ascii
>> ... Presumably PPS
>> was ignored because the event based timing packets yield reliable
>> sub-millisecond offsets.  The driver and document should be brought into
>> the PPS era and be renamed the TSIP refclock rather than Palisades.
>> Palisades/NMEA + ATOM is the way to use these receivers.
> From the Acutime 2000 user guide: "The time tag provides a resolution of
> 320ns ...".  Is PPS going to be sufficiently better that it would outweigh
> the additional setup complexity?

It is not the resolution of the time tag that matters, but the accuracy
at which it can be received by an asynchronous serial port.

You will probably require fudge configuration to calibrate it to an
existing known-good source to get within 1ms of true time.
With PPS it should be easy to get within 10us without calibration.

I don't know what your requirements are, so it is difficult to judge
if what you have now is good enough.

More information about the questions mailing list