[time-nuts] Question about the PLL of Trimble Thunderbold

Bob kb8tq kb8tq at n1k.org
Wed Oct 24 17:54:32 EDT 2018


Hi

The Thunderbolt actually is not a real good solution if you want to synchronize to something other than GPS. It
depends on direct phase data from its internal GPS chip set to do the GPSDO magic. A board that has a PPS
signal between the GPS and “PLL” probably is a better way to go.

Even with a board that has a PPS internally, it’s not going to like an abrupt phase change between GPS and “something 
else”. It needs some customization of the firmware to handle this kind of transition. That makes your project more of a
“from scratch” kind of thing ….

Bob

> On Oct 24, 2018, at 5:02 PM, Ferran Valdés <vantta at hotmail.com> wrote:
> 
> 
> Hello everyone ! I am new in here. I got referred to time-nuts by a colleague, and after reading a bit, I think that is the right place for this kind of questions :)
> 
> I have in mind a project which consists in synchronizing two or more stable clocks (OCXO) disciplined by GPS.
> 
> However, would be great to have the option to disable the GPS on both sides at a given time and to synchronize them in a Master-Slave or directly by means of a protocol they could correct each other and synchronize themselves.
> 
> After some research, the Trimble Thunderbold board got my attention, as has everything I need to get the project started.
> 
> Before getting a pair of the boards, on the datasheet is explained that one can get the unit on a disconnected state and adjust the ADC which drives the OCXO directly (that’s one of the desired capabilities !).
> 
> The question is: does anybody know if the phase difference (input of the PLL) can be read, in order to know how to steer the ADC ??
> 
> Alternatively, could you please suggest another board that would fulfil the following?
> 
> - GPS can be disabled.
> - has a serial com port, so commands can be sent to the unit and information can be retrieved.
> - provides 1PPS and 10MHz signals.
> 
> Thank you very much for your attention,
> Ferran
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