[time-nuts] GPS module recommendation for Pi timing

[Bob kb8tq]

Hi

If you always operate in fixed locations, your chances of seeing a slip
are not that high. The original post question and reference here were to
timing in a *mobile* situation.

Bob

> On Mar 13, 2020, at 4:14 PM, Hal Murray <hmurray at megapathdsl.net> wrote:
> 
> 
> Thanks.
> 
> kb8tq at n1k.org said:
>> One of the ways a GPS module “freaks out” is to slip by one code cycle
>> (which is just slightly over 1 ms). If you have a surveyed location, some
>> firmware will reject the solution and at least you will be in holdover.
> 
> If it slips, how long does it stay slipped?
> 
> I have plenty of old GPS units.  I'm a bit surprised I haven't noticed 
> something like that.  Maybe I'm not looking hard enough and/or in the right 
> place.
> 
>> In a case where the *only* thing you can trust is the GPS, filtering isn’t
>> going to do much good. 
> 
> You also have the CPU crystal.  It's not good for long term stability, but 
> shouldn't have any troubles holding to a ms over several seconds.
> 
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
>