[time-nuts] Holdover recovery

[Azelio Boriani]

The only english text I'm able to find is:

Analysis of the GPS frequency reference stability

Laboratory analysis of the dynamic
behaviour of some GPS receivers has
allowed to identify a criticality in their
use as ‘clocks’ to synchronize DVB-T
SFN networks. To fix this criticality, the
Research Centre has defined a new criterion
for the design of GPS equipment
for use in broadcasting applications.
This criterion is proposed as an Italian
contribution to the ITU


On Mon, Apr 4, 2016 at 10:10 PM,  <timeok at timeok.it> wrote:
> Here the italian version:
>
> http://www.crit.rai.it/eletel/2012-1/121-2.pdf
>
> Luciano
> www.timeok.it
>
>
> On Mon 04/04/16 21:28 , Magnus Danielson <magnus at rubidium.dyndns.org> wrote:
>
>> Hi Hal,
>>
>> On 04/04/2016 05:39 AM, Hal Murray wrote:
>> >
>> > Has anybody studied what happens when a GPSDO comes out of holdover? Has
>> > anybody seen any specs? I don't think I have.
>> >
>> > I think you have a choice of quick recovery for time or frequency, but
>> you
>> > can't get both.
>> >
>> > Suppose your setup has been in holdover for a while. The frequency is
>> > slightly off. The time offset of the PPS pulse will be the integral of
>> the
>> > frequency offset.
>> >
>> > What happens when you come out of holdover? If you fix the frequency,
>> the
>> > PPS will stay off.
>> >
>> > Suppose the PPS has drifted by 1 ns. If you correct that in 1 second,
>> the
>> > frequency will need to be off by 1E9 during that second.
>>
>> The RAI laboratory in Torino have made such tests and published
>> measurements and recommendations. For a long time it was only available
>> in italian, but there is now an english version available.
>>
>> Cheers,
>> Magnus
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