[time-nuts] PRS10 not locking to 1PPS

[Stewart Cobb]

>
>
> > Hello Time-Nuts,
> >
> > I am an user of a PRS10 Rubidium standard.
> > The unit has firmware revision 3.15.
> > After reset to factory settings the Time Offset (TO) was set to 1814.
> > Normally it was -1814. Now de PRS10 is not locking to the 1PPS anymore.
> > It will freeze when PL = 1. It will freeze after 256 seconds.
> > Is there a known way to set the TO back to -1814 for the firmware
> revision?
> > As it is a factory setting for this firmware revision.
> >
> > Regards,
> > Erik pe1RQF (former time keeper for the Netherlands at VSL)
>

Many surplus PRS10s came from the factory configured in ways which make it
difficult to lock to an external pulse. I do not know of a way to update
the factory configuration.  The internal microcontroller is a
one-time-programmable (OTP) version of a 68HC11. Its firmware is not
upgradeable.

However, the "freeze" you are reporting may not be permanent.

I always use the SRS official "RbMon" software to talk to a PRS10.   I have
one which has TO fixed at zero. This is not the correct value (which
appears to be around -1830). This unit will in fact lock and maintain lock
to an incoming PPS, as measured by external counters. The RbMon display
will be normal whenever the input pulse measurement TC is positive.
However, if TC goes negative, RbMon appears to freeze until TC goes
positive again. New data will occasionally appear, especially in the
frequency control signal words in the lower left corner, but the display
generally appears frozen until TC goes positive again. Despite the frozen
display, the actual clock stays locked to the incoming PPS regardless.
Perhaps this is the case for your clock as well.

I don't know whether this apparent freeze is caused by software inside the
PRS10 or by RbMon.

Cheers!
--Stu