[time-nuts] GPS module recommendation for Pi timing

[Bob kb8tq]

Hi

If you are laying out a board and building quite a few, shop for one of the
< $10 modules. What’s out there changes almost month to month so 
research is needed. As long as you get a PPS out, and a fairly rational 
serial i/o, mating them up should not be to crazy. 

You might spend the money you save on the GPS buying a “real” RTC 
chip ….. They aren’t crazy expensive and mate into the Pi environment 
pretty easily. GPS can come and go unless the antenna is in a really
good location. 

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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