Have you any reference? A TBolt, Z3801 or similar?
On Mon, Apr 22, 2013 at 9:53 PM, Daniel Ginsburg <dginsb...@gmail.com>wrote: > Hi all, > > I have bought a Resolution SMT GG for me to play with, and build a very > simple breakout board. > > The receiver appears to be working (in a sense). That is, it powers up, it > emits valid TSIP, it was able to survey it's position - a sane one. Trimble > GPS Studio is able to recognize it, and extract validly looking data from > it. In other words, I don't believe I have botched the module while > hand-soldering it. > > Now I have hooked it up to a stm32f4discovery board to sync with PPS. > That's were the weirdness begins. > > First, the frequency offset of the microcontroller. I use a built-in > counting timer in the uC which runs at 84MHz to measure the duration > between 2 PPS. What I get is ~84008000 timer ticks between two pulses, > which corresponds to about 95ppm offset. While the crystal on the board is > of the cheapest variety, I think 95ppm is just too much. Is that correct, > and 95ppm offset even for a the most crappy oscillator is not a reasonable > value? > > Second, the GPS sawtooth. The PPS does exhibit sawtooth, which is > expected. But the sawtooth is HUGE. While the spec claims +-15ns, I see > more that +-400ns with period about 30 seconds. This is not sane. I must > have done something totally wrong. > > Something has to be terribly wrong with my measurements. I'd really > appreciate any hints on how to find out the cause of the described > weirdness. > _______________________________________________ > 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.