[time-nuts] PRS10 not locking to 1PPS

[Tom Van Baak]

Hi Erik,

That's a very fine experiment you did.

Can you apply a known 1PPS and collect an hour of PP? readings. That 
might help distinguish between a problem with time-tagging in general 
and a problem with disciplining the Rb.

/tvb


On 1/7/2021 7:03 AM, e.j.kroon at vathorstnet.nl wrote:
> 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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>>
>>
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