[time-nuts] PRS10 not locking to 1PPS

Thu Jan 7 15:03:23 UTC 2021

Hi All,

I have done an experiment using the PSR10.
I have set the Magnetic offset to mid-range MO2950
Than set the Set frequency to 0 SF0. To have 0 frequency offset.
Measured the output frequency and calculate the average deviation.
By using the Frequency Synthesizer Table from Appendix A I have selected the
smallest frequency deviation by changing via the Frequency Synthesizer
Control command SP.
Than measured the frequency deviation again and use the Set frequency
command for 
the correction of the deviation (by SF). By monitoring the Magnetic read you
are able to see 
the Magnetic C field effect from the SF setting. Than enter the Magnetic
offset to the value of
magnetic read via MO. Finally set the SF to 0. 
By this procedure the frequency deviation is < than a few parts to -12. 
And within the Magnetic offset range. 
However still the 1pps control is not working and stops the internal time
interval.
Maybe by corrupted eprom TO setting.
But the unit is good for un-steered operation. 

Thanks for your help

Erik (PE1RQF)

-----Original Message-----
From: time-nuts <time-nuts-bounces at lists.febo.com> On Behalf Of Dana Whitlow
Sent: maandag 4 januari 2021 21:02
To: Discussion of precise time and frequency measurement
<time-nuts at lists.febo.com>
Subject: Re: [time-nuts] PRS10 not locking to 1PPS

Erik, the PRS-10 does have provisions for changing the internal
synthesizer's "ratio",  which could provide a way of getting an essentially
fresh start on aging.
There's a
big table of values somewhere in the documentation (but not necessarily in
any convenient order).

My old PRS-10 is getting towards one end of its magnetic tuning range and
will probably "die" in another couple of years use, but I have high
expectations of winning it back via this mechanism.

Have you looked into this?

Dana

On Mon, Jan 4, 2021 at 1:36 PM <e.j.kroon at vathorstnet.nl> wrote:

> 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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