Guru
Joined: 02/02/2017
Location: AustraliaPosts: 1442
| Posted: 08:47am 27 Nov 2024 |
no promises that it will work for ever but it works now.
http://1eq2.cc/f3.html
this is the frequency at Melbourne and the phase, relative to some
starting point and that is not important.
Phase locking does not care about any absolute phase angle, just what it is now.
phase angle change rate is proportional to frequency, by the way.
I measure phase angle by getting the time of zero crossing AC
compared to the GPS 1 second pulse from a GPS module.
I also tune up (or discipline) the local timer of the microcontroller
so as to get accurate frequency.
My estimate of error of frequency is about 0.01%
in other words it's really good.
The GPS 1 second pulse has jitter of the order of 50 or so nanoseconds.
This can be used to average out the jitter and get a very good time source.
I maintain a local 1 second pulse and bring it into close relation to the GSP 1 second pulse using closed loop control (a phase locked loop as it were)
It's good.
Edited 2024-11-27 18:53 by poida
wronger than a phone book full of wrong phone numbers