Re: GPS time sync with chrony and ESE serial device

[Devren Yener]

Thanks very much Gary for your help and advice!  We were afraid we might have to buy new equipment, but I figured it's a simple enough signal, I'd be very surprised if there isn't some way to get it working in Linux. (It works in Windows and DOS after all, with the manufacturer's ancient software... but I don't want to use these for a time server!)

To address your point about the GPS lock, there is supposed to be a GPS lock signal from the receiver.  According to the specs, pin 8 in the DB-9 serial connector carries "GPS Lock".  I imagine this is just a constant binary "on" or "off" signal. Likewise, pins 4 and 5 carry the PPS signals, and pins 2 and 3 carry the RS-232 ASCII text timestamps and control signals.  (There is also a GPS Lock LED indicator on the device itself, so I know that it knows when it has a lock.)

Do you still think gpsd will not be able to work with the signal?  If so, I won't pursue it further!  I really appreciate your advice.

Thanks,

Devren

On Tue, Mar 3, 2020 at 3:40 PM Gary E. Miller <address@hidden> wrote:

Yo Devren!

On Mon, 2 Mar 2020 15:07:44 -0500
Devren Yener <address@hidden> wrote:

> I am trying to configure a Linux box to sync time over a serial cable
> with an old GPS clock we have. I seem to be getting the expected data
> over the serial cable, but I cannot get the gpsd and chrony
> configuration working to actually sync the time.

It happens.

> I have looked
> through the HOWTO document at
> https://gpsd.gitlab.io/gpsd/gpsd-time-service-howto.html, and I am at
> a loss regarding what else I can try.

You came to the right place.

> The device is an 'ESE Master Clock ES-102'. It does not give full GPS
> data, but only an ASCII timestamp and a 1PPS signal.

Well, there is your problem.  Note the "gps" in gpsd?  Gpsd will not
pass on PPS unil the receiver tells gpsd it has a 2D lock.  Your receiver
does not do so.

This is because a lot of receivers spray random time until they get
a lock.

Good new receivers are cheap.  Junk your old klunker.

RGDS
GARY
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