Re: [Discuss-gnuradio] Channel model - the identity channel

[Andrej Rode]

Hey Raj,

> introduces a delay that can be corrected by applying the taps [0,0,0,1].
> See the attached flowgraph that subtracts the signals before and after
> the channel model; if you let taps = 1, the two signals don't cancel. If
> you use taps = [0,0,0,1], they do. 

The delay you are seeing is introduced by the fractional_resapmler
inside the channel_model block. The FIR filter inside the fractional
resampler needs to build up and therefore introduces a initial delay of
three samples.

If you want to know more about the insides of the channel model I
suggest you look at the sources [0][1] yourself.

Greetings,
Andrej

[0] ./gr-channels/lib/channel_model_impl.cc
[1] ./gr-channels/lib/channel_model_impl.h

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