David Taylor wrote:
This was posted by lu...@fridolin.com on the NTP hackers list, just in case you missed it. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Hi, I've been writing a reference driver for u-blox GPS receivers as part of my master's thesis and thought ntp hackers might be interested in it. Additionally to normal PPS operation this driver can make use of the u-blox's "Timemark" functionality. It does this by enabling the PPSAPI echo, which generates an echo pulse right after receiving a PPS pulse. This echo is connected to EXTINT0 on the u-blox, where it is timestamped. So now I have the PPS timestamp as a local time and the timemark as the receiver time to calculate an offset. The cool thing about this is, that the offset does not include the local interrupt latency anymore, which leads to less jitter.
This is indeed cool, do you have any graphs/stats for the actual/remaining jitter?
Terje -- - <Terje.Mathisen at tmsw.no> "almost all programming can be viewed as an exercise in caching" _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
