[time-nuts] Speaking of Costas loops

ed breya eb at telight.com
Tue Jul 2 14:05:34 EDT 2013


This talk of Costas loops reminded me of something I wanted to 
investigate some day. I read somewhere a while back about 
carrier-phase measurements, and various methods for recovering the 
GPS carrier frequencies, including the Costas loop, and something 
with carrier-squaring. Nothing I found showed actual examples or 
detail of how this is done, only high-order mathematical descriptions.

For my needs, I'm more of a frequency-nut - I usually don't care 
about getting time info, but I'd like perfect 10 MHz for reference. 
Can using only the carriers lead to simple ways to get the same (or 
better) frequency stability as a conventional GPSDO, but without the 
time and location info, or is it pointless to worry about it, and 
just go with full GPS decoding of everything? Or, is carrier-phase 
just an enhancement only if you already have the full GPS info?

I know that the group could redesign the whole GPS system with tubes 
if necessary, considering recent philosophical discussions on that, 
so I think there's plenty of knowledge here about carrier-phase 
related stuff too.

Ed



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