On 19/08/2014 16:11, Ed Palmer wrote:
Does anyone have a neo-7M and an HP 5371A or a 5372A Analyzer? Use the Histogram Time Interval function to measure a block of samples. That will show the length of the samples with a resolution of 200 ps. That's what I did a couple of years ago when I analyzed the Navsync CW-12 with the old and new firmware.
FWIW, I just had a look at the timepulse on a NEO-7M. I configured it to 10MHz, 50:50 duty cycle when locked, disabled when out of lock. I don't have any of those Analyzers so I used an HP 54615B digital scope. The period of the majority of cycles was 104ns with 'random' cycles being 84ns. I did not observe any other cycle periods. I don't know how accurate the time measurements are on the scope, but it looks like the timing is derived from an approx 48MHz clock, and the timing phase/frequency adjusted by periodically deleting 48MHz clock cycles.
Although I said random, I couldn't make any observations as to the statistics of the short and long cycles or their distribution - I guess I'll have to write some software for my STM32F4 discovery board for that.
If I get time, I'll do the same with a Reyax RYN25AI receiver which has a UBLOX MAX-7C module.
Tony _______________________________________________ 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.
