In the UK (and much of europe), a broadcast time and frequency reference is available in the form of the MST radio time signal. This is broadcast using on-off keying on a frequency of 60 kilohertz, to within one part in 10^12.
I'd like to use this signal to construct a cheap and accurate 10MHz frequency reference. My tentative plan is to construct a PLL, with a VCTCXO as the VCO component, and lock it to the 60KHz reference. That's the easy part.
However, I'm not sure how to approach a couple of other aspects of the solution. Specifically:
- What's the easiest way to receive and amplify the 60KHz carrier wave, producing a clean 60KHz square wave output from the receiver?
- How should I handle the periods during which the transmitter is not sending the carrier wave (which can last up to 500ms, at the beginning of each minute)? I don't want the phase comparator to decide the clock is way out of phase and skew the TCXO frequency during this period.