[ntp:questions] ESR looking for good GPS clocks

Terje Mathisen "terje.mathisen at tmsw.no" at ntp.org
Tue Mar 6 11:14:22 UTC 2012

unruh wrote:
> On 2012-03-05, Terje Mathisen<"terje.mathisen at tmsw.no">  wrote:
>> while (1) {
>>     before = gethirestime();
>>     gps_time = poll_gps();
>>     after = gethirestime();
>>     if (after - before<  MAX_LATENCY)
>>       use_timestamp(after, gps_time);
>>     sleep(1);
>> }
> That is called ntp. (except it does it better) Why in the world should
> after be a better estimate than say (before+after)/2 Ie, what you want

Both are fine, I just want to verify that the query time is reasonably low.

> is for your gps chip to be an ntp server.

Not quite but I see what you mean.

> I could of course be done. But not for $100.
> And this is NOT a gps receiver.

Except for the fact that such gps receivers have existed for many year, 
even if they used a serial line interface, i.e. look at (afair) the 
Trimble Palisade driver.

- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"

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