Martin Gregorie  wrote:
> On Mon, 07 Dec 2020 15:55:32 +0000, Ahem A Rivet's Shot wrote:
> >       It rather depends on how long might elapse before reaching a time
> > server, if there's any danger of that being a long time then a RTC is
> > very helpful, if you're sure of a time server immediately after boot
> > then it's pretty much useless.
>
> Don't forget that an old GPS unit, provided it has serial NMEA0183 output
> which many of them had, can be used by ntpd as a primary time reference.
> These can be connected to an RPI via a USB-serial adapter. There is a
> reference driver for ntpd that allows it to accept an NMEA0183 primary
> time stream.

How long with a GPS unit take to get a time fix from cold, out of interest?

The OP's situation sounds like one where a RTC would be quicker than a cold
GPS, although maybe there's a way to get a time out of GPS before it has
seen enough satellites for a position fix.

(and can you do A-GPS by configuring the lat/long of your stationary Pi?)

Theo

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