How to use gr_clock_recovery_mm_cc

Hi All,

In the gmsk.py, the gr.clock_recovery_mm_ff is used.

I want to use gr.clock_recovery_mm_cc (float omega, float gain_omega,
float
mu, float gain_mu) (which implements Mueller and Mller (M&M) based clock
recovery block with complex input, complex output) to replace the
gr.clock_recovery_mm_ff

I have done these in two steps:

  1. use the same parameters (used to init gr.clock_recovery_mm_ff) to
    init
    gr.clock_recovery_mm_cc.
    omege=2.000000, gain_omega=0.000625, mu=0.050000, gain_mu=0.050000,
    omega_relative_limit=0.005000

  2. move the clock recovery block forward before demod block
    self.connect(self, self.clock_recovery, self.fmdemod, self.slicer,
    self)

Before modification, if I run the benchmark program using gmsk, receive
rate
is almost 100%, but after my modification, receive rate drops to 0%.

Does my method have problem, any help is appreciated!

On Tue, Jun 7, 2011 at 9:13 AM, Shen W. [email protected]
wrote:

  1. use the same parameters (used to init gr.clock_recovery_mm_ff) to init
    Does my method have problem, any help is appreciated!


Wenbo

You HAVE to use the clock recovery after the demod. Pre demodulation,
you
don’t have the right type of signal to lock against.

Tom

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