modulating time markers

Jan 18, 2025 Last reply: 1 year ago 2 Replies

I'm looking into a time marker modulated onto a rf carrier that is simple and at the same time accurate. The marker on the low frequency signal carrying the US time reference which is said to invert the carrier to mark the time certainly sounds simple. The remarkable accuracy of the RTK GPS devices, actual inches are claimed, suggests a very accurate means of reading the time marker. Anyone know of a text that deals with such circuitry or perhaps a schematic of a gps reciever with enough detail to show how it's done?



Hul


Dear Hul Tytus:

Happy New Year!

This is not as requested but might help to go to where you want to. In the Year that is called 2009 I reviewed "Fundamentals of Global Positioning System Receivers - A Software Approach" by James Bao-yen Tsui. It does not contain schematics. My copy is in storage so I cannot look it up to say what its index or table of contents say about encoding timing or radio signals. Sorry! Good luck!

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GPS is extremely complicated and studying it is probably not worth your while if you're only trying to modulate a time signal onto an RF carrier. For that, look at basic RF digital modulation techniques. Are you trying to get microsecond accuracy? Sub-millisecond? Sub-second? It gets easier at coarser levels. You stop having to account for speed of light delay between the transmitter and receiver, relativistic corrections because of the endpoints being in motion, etc.

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