[ntp:questions] using both a PPS source and a HBG (dcf-77-like) timesource?

Uwe Klein uwe_klein_habertwedt at t-online.de
Tue Jan 15 12:17:28 UTC 2008

Unruh wrote:

> Yes, 185 ms is about how long it takes to read the nmea string (about 70
> characters as 4800 baud is about 1/6 of a second) YOu can tell ntp to
> subtract off say 180ms but that would still leave you with a sizeable
> jitter. 

you will retain
the jitter of the receiver sampling interval (usually baud /4 or /8)
and probably some others:
the beat between Baudrate sampling clock and Busclock.
variations in interrupt latency ..

most microcontrollers should be able to send a deterministic datagram
i.e. exactly the configured number of Stopbits between all bytes sent.


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