Unruh wrote: > I do not understand this. You seem to be measuring the offsets, not the > frequencies. The offset is irrelevant. What you want to do is to measure
Measuring phase error to control frequency is pretty much THE standard way of doing it in modern electronics. It's called a phase locked loop (PLL) and it is getting difficult to find any piece of electrnics that doesn't include one these days. E.g. the typical digitally tuned radio or TV has a crystal oscillator, which is divided down to the channel spacing or a sub-multiple, and a configurable divider on the local oscillator divides that down to the same frequency. The resulting two signals are then phase locked, by measuring the phase error on each cycle, low pass filtering it, and using it to control the local oscillator frequency, resulting in their matching in frequency, and having some constant phase error. > the offset twice, and ask if the difference is constant or not. Ie, th > eoffset does not correspond to being off by 5Hz. ntpd only uses this method on a cold start, to get the initial coarse calibration. Typical electronic implementations don't use it at all, but either do a frequency sweep or simply open up the low pass filter, to get initial lock. _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
