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Re: [Discuss-gnuradio] Why d_phase in Costas loop different in gr_costa
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From: |
Jason Uher |
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Subject: |
Re: [Discuss-gnuradio] Why d_phase in Costas loop different in gr_costas_loop from gr_mpsk_receiver? |
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Date: |
Wed, 27 May 2009 07:35:38 -0500 |
> gr_costas_loop is wrong, and gr_mpsk_receiver used to have the same
> error and has since been updated. The frequency component of the
> rotation has already been added to the current phase estimate during
> de-rotation of of the samples (in mm_sample, I think); so here all we
> have to do is update the phase estimate by the estimated error.
DOH! I it's still early for me.
gr_costas_loop is /not/ wrong. The reason that d_freq is added is
because the phase advances normally over time, and this line updates
the phase estimate for both changes over time and the error.
It is not need in mpsk receiver because it is split into two parts
(one in mm_sample and one where you got that line from).
Sorry for the confusion.
Jason