Yo Ilia! On Thu, 20 Oct 2016 06:15:39 +0000 Ilia Platone <[email protected]> wrote:
> I am trying to take some timestamps of events on a GPIO using an ARM > SBC, and noticed that the kernel linux can be interfaced to a PPS > signal, wanted to sync another GPIO to a GPS receiver for time > reference. You should check out the gpsd time howto, and ntpsec. http://www.catb.org/gpsd/gpsd-time-service-howto.html https://www.ntpsec.org > I need to know how much precise this system can be. How > much resolution can I obtain with a cheap receiver (maximum > quantization frequency)? On average, on a RasPi 3, you can expect about > Formulas are well accepted. How about a graph, or two? See attached. From the histogram, I suspect the granularity is about 200 nano sec. From the offset graph you can see how the offset jumps. Here is the offset data on PPS v. the system clock: Percentiles...... Min 1% 5% 50% 95% 99% Max -21.645 -2.587 -0.834 -0.020 0.991 0.991 13.557 µs Ranges...... 90% 95% StdDev Mean Units 1.825 5.318 0.850 -0.006 µs Or see a lot more live graphs here: https://pi4.rellim.com/day/ RGDS GARY --------------------------------------------------------------------------- Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703 [email protected] Tel:+1 541 382 8588
pgpxhRJtHmnX_.pgp
Description: OpenPGP digital signature
_______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
