Re: [Discuss-gnuradio] Help needed to obtain AM Depth of Modulation

[Matt Cooper]

I've been doing some tests, and something strange is happening:

- If I set the generator at 50% modulation depth and I simply plot the
source input, I get  this result <http://i.imgur.com/BLe15C4.png>  , which
is different from the  graph from Wikipedia
<https://upload.wikimedia.org/wikipedia/commons/thumb/b/b0/Amplitude_Modulated_Wave-hm-64.svg/400px-Amplitude_Modulated_Wave-hm-64.svg.png>
 
; in my graph the peaks and valleys of the envelope at the top are not
"synced" with the ones of the bottom envelope. Any ideas of why can this be
happening?

- Also, if I convert the source from complex to magnitude, I get a  strange
waveform <http://i.imgur.com/qpxbrw0.png>  , but the peaks at the bottom
envelope correspond inversely to the modulation depth set in the generator.
For instance, if I set the depth to 30%, the peaks reach 0.7 in amplitude.
If I set the depth to 80%, the peaks reach 0.2 in amplitude. This might be
useful for me! Is there a way I can use this information as a number output
to get the modulation depth ratio in real time?

Thanks for your help!



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