Re: [Discuss-gnuradio] gr.firdes_hilbert () usage

[Matt Ettus]

Feed a real signal to the hilbert filter to form the Q part of a complex signal.
   Feed a delayed version of the original signal to the I part.  The delay
should be equal to  .5*(number of taps of the hilbert filter - 1)

Matt


Quoting cswiger <address@hidden>:

> Gang - how is the hilbert filter taps used?  Either I don't understand
> hilbert or how to use gr.firdes_hilbert.
>
> If I feed a complex signal directly to output plot I get the expected
> signal for positive and negative freq.  However if I feed it thru a
> hilbert filter first there's a phase shift but there doesn't seem to be
> any difference for positive or negative freq. Or maybe I'm not looking
> at them right.
>
>
>       signal = 10e3   ; set positive or negative
>       sample_rate = 1e6
>       cfir_decimation = 1
>
>       src = gr.sig_source_c (sample_rate,gr.GR_SIN_WAVE,signal,1.0,0)
>
>       hilbert_coeffs = \
>               gr.firdes_hilbert (37, gr.firdes.WIN_HAMMING)
>
>       hilbert = gr.fir_filter_ccf (
>               cfir_decimation,
>               hilbert_coeffs )
>
>       dst - gr.file_sink (gr.sizeof_gr_complex, "hilbert_2_pos.dat")
>
>       fg.connect (src,hilbert)
>       fg.connect (hilbert,dst)
>
>
> --Chuck
>
>
>
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