• seblleb

    my mistake sry. :pray:
    thanks a lot! now it works with the positive feedback coeefficients.
    with 440Hz Testtone and 2000Hz carrier I now get -60dB attenuation when demodulated.

    posted in technical issues read more
  • seblleb

    Thanks for the replies!
    @jameslo I am using sonic visualiser to plot the spectra and measure stuff. its very pretty. also for waterfall diagrams
    here you see the analog concepts we implement completely from discrete components: [ https://sound-au.com/project204.htm](link url)
    the math behind single side band is quite easy. In pd I wanted to do a simulation of it just to see how it interacts with other stuff I build.

    @manuels and @Obineg so I tried with opposite signs which was fun waveshaping weardness, but no 90° phase shift.

    then I tried to replace the hilbert~ object with a phasor~ and two cos~ but with 90° phase shift as it is used for the modulator and it worked "clean" regarding the sideband.
    I have only seen Harmonics from over driving somewhere. thats also a thing that confuses me. When modulating like this the signal clearly shouldn't go below 2 so multiplying by 0.5 should attenuate enough to get a linear response.

    could you further explain what you mean by: it kind of only happens with sine or harmonic? If there is no input signal I have the 2* f_modulator bleeding at -40dB.

    also I thought about the one sample delay i made with rzero_rev~ 0, it translates to y[n] = x[n-1] and means a onw sample delay. am I right with that or do I miss sth?

    posted in technical issues read more
  • seblleb


    I played around with sideband modulation using the hilbert~ object and was wondering about the sideband attanuation performance. Here is my patch:

    Screenshot from 2022-10-25 12-11-17.png

    In the picture below you see my modulated output in the first pane and the demodulated output in the second pane. Testsignal is a 440Hz sine shifted by 2000Hz.

    Screenshot 2022-10-25 at 12-08-10 Proton Mail.png

    what I dont understand is why is there only 40 dB attenuation between the 2 Sidebands?
    Is this because the hilbert~ isnt perfect 90° over the frequency range?

    I tried to implement hilberto~ from this blog https://www.katjaas.nl/hilbert/hilbert.html on the very end you see the Max patch
    but its output was not more, but at least, decent glitches... : I dont get what I did wrong here.

    Screenshot from 2022-10-25 12-18-42.png

    any input is appreciated, :smiley:

    posted in technical issues read more

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