[Discuss-gnuradio] Why no phase ambiguity in digital-bert...

[Ian Holland]

Hi All

I have been studying up on the Costas loop, and have a couple of queries as to the benchmark_tx.py and benchmark_rx.py as a result.

Firstly, for BPSK, there should in theory be a 180 deg. phase ambiguity when using a Costas loop. Why does this not seem to occur with the benchmark_rx.py example? Is this related somehow to the PN code introduced by the scrambler.

Secondly, I came across another post in which it was mentioned the Costas loop should only operate on a single sample per symbol. However, as I read the source code, it seems as though it is actually passed sps samples per symbol, where sps > 1. Have I misread something here?

Any help in these matters would be greatly appreciated.

Thanks

Ian.