Forum: GNU Radio Does USRP do phase estimation when down convertion?

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596af7df4dff49c792ef1796d3abbb20?d=identicon&s=25 isulsz (Guest)
on 2009-05-31 22:55
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When USRP down convert the passband signal, does it perform phase
Or in other words, does the phase of the sin wave from the local
lock to the phase of the incoming signal?

Phase is needed in coherent demodulation. I just want to know where it
performed in the USRP and GNU radio. I conjecture that the USRP does not
estimate the phase and the demodulator does phase estimation, for
in gr_mpsk_receiver_cc. But I am not sure.

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998dbc3ac73d5487c59c0ee0f5baeeb1?d=identicon&s=25 Sebastiaan Heunis (Guest)
on 2009-06-01 00:21
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The DDC on the USRP only mixes the signal down using the CORDIC
algorithm.  The CORDIC only multiplies the input signal by scale
values corresponding to cos and sine.  The phase estimation should
happen in the C++ code on the PC then.

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