[time-nuts] BPSK Receiver & GPS Antenna siting

[Jim Lux]

On 9/27/12 4:34 PM, Bob Camp wrote:
> Hi
>
> A PLL locks to phase. If the phase switches by 180 degrees, the phase tracking switches signs. There's no way to track that. You either need to double the frequency (and thus eliminate the modulation) or demodulate the signal and lock to the result. If you simply put up a real narrow filter and hit it with continuous 180 degree phase shifts, the output will be nothing at all…
>
>
that's the whole thing about the inphase arm on a Costas loop.. that 
gets multiplied by the phase error signal from the quadrature arm and 
fixes the sign flip from the modulation.