>How precise can a 4800 baud serial port be in determining the start of a >start bit? About 1/4800s i.e. about 200 microseconds? Don't the chips >sample at 8 or 16 times baud rate, so couldn't the start bit be determined >to ~25-30 microseconds? And if the baud rate was lot higher (the unit >claims 57600 baud)? > >You would be using the unit in a slightly different mode to an existing >GPS - just detecting the start of an RS-232 burst for the PPS, and then >reading a message for the actual value....
What you describe could be made to work quite well, but I've never seen one that works that way. The data sheet says 1 microsecond. It also says SiRF chip set. All the SiRF units that I've tested are horrible. They aren't even trying for good timing. My guess is that the 1 microsecond was copied from another data sheet that did have a PPS signal. If anybody tests one of these, please let us know how well it works. -- These are my opinions, not necessarily my employer's. I hate spam. _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
