[time-nuts] GPS module recommendation for Pi timing

[Brian Lloyd]

On Fri, Mar 13, 2020 at 9:20 AM Jim Harman <j99harman at gmail.com> wrote:

> Is this application for a product that you will be selling in quantity and
> producing over time, or a one-off or low volume application?
>

It will have a run of at least 100 units, maybe more. I would like it to
have a decent lifetime in case we need to make more.


> On Fri, Mar 13, 2020 at 10:07 AM Brian Lloyd <brian at lloyd.aero> wrote:
>
> > I have an application where I need to synchronize the internal TOD RTC
> in a
> > raspberry pi and need to pick a GPS module. We are building our own
> > hardware but still using the Pi so interconnection will be via
> GPIO/serial.
> > We won't try to use USB.
> >
> > This is not an NTP application. These units will be in the field and will
> > most likely not have Internet access. I need their clocks to be pretty
> > close. I am shooting for 1ms ... if possible.
> >
> > The new M9F and M9T modules from Ublox are a bit pricey. The M8T is a bit
> > more reasonable. OTOH I realize there are limits to how tightly I can
> > control the Pi's RTC and will run into diminishing returns, so even the
> M8T
> > might be overkill.
> >
> > Has anyone here figured out what the reasonable limit is for timing on a
> > Pi, and what makes sense for a timing module for an application like
> this?
>
>

-- 



Brian Lloyd
706 Flightline
Spring Branch, TX 78070
brian at lloyd.aero
+1.210.802-8FLY (1.210.802-8359)