[time-nuts] GPS module recommendation for Pi timing

Bob kb8tq kb8tq at n1k.org
Fri Mar 13 18:43:59 UTC 2020


Hi

One as yet un-asked question: 

Is this a dynamic or a static application? If static, is there time to do a 
proper survey of the location? Normally that all matters for accuracy.
In this case it mostly matters in terms of dropouts / code slips. A 
code slip would indeed nuke your “one ms” budget.

Bob

> On Mar 13, 2020, at 11:17 AM, Brian Lloyd <brian at lloyd.aero> wrote:
> 
> On Fri, Mar 13, 2020 at 9:59 AM Peter Membrey <peter at membrey.hk> wrote:
> 
>> Hi Brian,
>> 
>> We published this back in 2016 but it provides an analysis on the
>> stability of the STC on the first three generations of Raspberry Pi as well
>> as the stability profile of the uBlox M8Q:
>> 
>> https://crin.eng.uts.edu.au/~darryl/Publications/Pi-hat_current.pdf
> 
> 
> Thank you. Perfect. Reading now.
> 
> Bob KB8TQ: We are laying out our own board as it will be doing other things
> besides GPS time/frequency keeping. Trying to avoid the use of USB. 1pps
> will go directly to a GPIO pin, assuming that will provide the best
> performance.
> 
> Hal Murray: Yes, I am trying to discipline the system clock.
> 
> Arne: Yes, I was considering using gpsd.
> 
> Right now I am leaning toward the Ublox LEA-M8T. I have a use for the other
> programmable output from the Ublox.
> 
> 
> -- 
> 
> 
> 
> Brian Lloyd
> 706 Flightline
> Spring Branch, TX 78070
> brian at lloyd.aero
> +1.210.802-8FLY (1.210.802-8359)
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