[time-nuts] PRS10 not locking to 1PPS

[e.j.kroon at vathorstnet.nl]

Hi all,

The PSR10 is working now for 15 years at my place (total >25 years).
For the 1pps a Trimble Resolution T is used and has a good 1pps signal.
The Magnetic Offset MO is on the limit value of 2300 when using the 1pps correction.
Therefore I think the unit is on end of life. I tried a factory reset to see what will happen.
However due to the change of the TO to 1814 the unit stopped measuring the 1pps time pulses
after 256 measurements and no 1pps measurement are possible when PL=1.
The other values are responsive. Only after a RS1 it will measure again the pps.
My thought was due to the strange TO of 1814 (before factory reset is was -1814)
the internal calculation is messed up. 
When PL=0 the pps measurements continues but the MO is not controlled to GPS.
I am not sure how to update the firmware. 
While the unit is still stable, it has now an frequency offset of -2.7E-10 Hz/Hz stability still is
2.4E-12 for 20k seconds.
Probably I need another rubidium frequency standard.

ST5 when PL=0
3 = PPL disabled,  < 256 good 1pps inputs Provide stable 1pps inputs

ST5 when PL=1 and when 1pps hangs
4 = Excessive time interval (while 1pps is still good of the GPS)

Regards,
Erik (PE1RQF)




-----Original Message-----
From: Miikka Raninen <miikka.raninen at gmail.com> 
Sent: zondag 3 januari 2021 21:44
To: time-nuts at lists.febo.com
Cc: e.j.kroon at vathorstnet.nl
Subject: PRS10 not locking to 1PPS

> 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)

Ref manual for PRS10 :
https://www.thinksrs.com/downloads/pdfs/manuals/PRS10m.pdf

Check the quality of the input 1PPS. When the unit fails to lock on to 1PSS input after 256 seconds it is usually due to the 1PPS being too unstable in phase

What do you mean by freezing? Can you check the status bytes with ST?
command? They might indicate the reason for the fault :

ST5: Frequency Lock to External 1pps
ST5 bit Condition which sets bit Corrective Action

0 PLL disabled Send PL 1 to enable
1 < 256 good 1pps inputs Provide stable 1pps inputs
2 PLL active
3 > 256 bad 1pps inputs Provide stable 1pps inputs
4 Excessive time interval Provide accurate 1pps
5 PLL restarted Provide stable 1pps inputs
6 f control saturated Wait, check 1pps inputs
7 No 1pps input Provide 1pps input

You might also want to consider updating the firmware as "(Note:
Firmware revisions prior to Rev 3.23 do not allow user TO! commands.
Check the firmware revision with the ID? command)"

- Miikka Raninen OH3GPJ


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