Hi Is your GPS module a GPSDO or is it something more basic? If it's a GPSDO, then it's accuracy is not an issue. If it's a basic navigation board, then it could easily be off by enough to impact the results.
Bob On Dec 1, 2011, at 7:41 PM, Tom Harris wrote: > I finally have a need to ask a question about time measurement! > > I want to measure the accuracy of a 1Hz signal from a real time clock > (RTC) chip with an integrated TXCO allegedly good for +/- 2ppm > accuracy. My employer is too tight to buy a good frequency counter, > but I do have a GPS module outputting 1PPS. If I use a little micro > running at 16MHz from a jellybean crystal to measure the period of the > 1PPS signal from the GPS concurrently with measuring the period of my > test signal, will I be able to get accuracy of sub ppm? My resolution > for a single period is 62.5 ppb, but this is a lot different to > accuracy. I could easily count multiple periods, as I do not need fast > results. My thought is that the 16MHz will have jitter and a > pronounced drift, but that as the measurements of my reference and > signal are done nearly concurrently, the errors will be very small. > > The need for this is that the RTC chip for a product has the engaging > property of shifting it's frequency by several ppm after being > soldered to the board, and I need to characterise this to get accurate > timing for the product. > > -- > > Tom Harris <celephi...@gmail.com> > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
