Hi Martin, Martin Burnicki wrote:
> Some times ago we had made some tests with some serial-to-USB converters > which are connected to the PC via USB and provide a serial port to which > serial devices can be connected. We have been using our GPS receivers which > send a serial time string once per second as soon as possible after a > second changeover. The jitter of the serial output is 1 bit time depending > on the baud rate, i.e. ~52 microseconds @ 19200. Yes, if one needs further improvements one would try to sync the baudrate generator to the pps clock. with some tricks in the sending routine one then could transmit in a coherent fashion. Though you still retain the receiver uncertainty ( 1/16.. 1/64 of a baud cycle depending on async receiver used ) > > Some of the tested devices introduced a very low latency whereas others > indroduced a much higher latency. So this depends in fact on the maybe the > chip set and in any case the driver/firmware used for the converter. Have you got vendor/product Id pairs for those? on windows/linux/bsd/* ? I'd be interested in related information. > > >>Thus my guess is that these latency may lie in the firmware running >>on the sirf chipset. > > > Of course, if the firmware already inserts some latency then the > serial-to-USB converter is not to blame and can not eliminate it. > > Martin uwe _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
