Wednesday, April 26, 2017

Re: [Discuss-gnuradio] WBFM modulation/demodulation high frequencies highly attenuated

It seems I using the block I should not use:  WBFM TRansmit
Documentation for this block may be found at
https://github.com/gnuradio/gnuradio/blob/master/gr-analog/python/analog/wfm_tx.py#L67
It includes a preenfasis and a low pass filter with passband ending at 16Khz  so I can't use it for a FM stereo transmission whose bandwidth is 53Khz.
I think i should use the block Frequency Mod, although I can find many information about this block.

regards



El 26/04/17 a las 20:02, Fernando escribió:

I'm modulating/demodulating a wide band FM signal and I observe that high frequencies are highly  attenuated.

This is the diagram


And this is the spectrum

High frequencies are attenuated more than 40dB over low frequencies.

It seems to happen for frequencies above 20Khz.

Changing max deviation in WBFM Transmit has no effect.

What am I doing wrong?


regards




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