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 FM with IQ 
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Location: Burnley, IO83VT
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Post FM with IQ
Hi all,

In my spare time I've been trying to understand how different modulation types work with IQ signals. Thus far I've managed OOK and AM. I've now moved onto FM. I'm using:

out[i] = cos(X[i]) + j sin(X[i])

to create the output IQ sample from the input signal X at baseband. However when I listen back to this signal on my radio, demodulating with NFM it sounds very very distorted.

I have some questions about what I'm doing:

Is the above correct for generating an FM signal?
I'm presuming that the signal is being over-modulated and that's why I'm hearing distortion?
I've ran X through a low-pass filter at 6.25kHz, which I think would then give a signal at 12.5kHz deviation?
Is there anything else I could try to attempt to reduce the distortion heard on my radio?

Thanks!
Matt


Wed Nov 18, 2020 10:52 am
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