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812Re: [SpectrumLabUsers] Q: screen capture as CSV file?, complex FFT?

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  • ehydra
    May 31, 2012
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      wolf_dl4yhf schrieb:
      >> 1. I need the FFT spectrum as a captured screen file but not as picture.
      >> It should be a CSV file or such. Is this possible? I looked in the
      >> online help but there is only doc for pictures. Say something like:
      >> frequency SPACE linearAmplitude CRLF
      >>
      >> with decimal point, not comma.
      >>
      > Not necessarily CSV, but this may be similar to what you are looking for:
      >
      > http://www.qsl.net/dl4yhf/speclab/textexpt.htm#export_fft_results
      >

      Looks like all is in one line. Hm. I will try this converting it with Perl.


      >
      >>
      >>
      >> 2. My second question is: if it is possible to make a complex FFT to
      >> measure impedances and getting amplitude and phase back?
      >>
      > Not sure.. to measure an impedance we'd need something proportional to
      > the current fed into one input, and something proportional to the
      > voltage fed to the other. The complex FFT (i.e. FFT of a complex input
      > signal) has another use: Here, the two inputs are used to distinguish
      > 'positive' and 'negative' frequencies.
      >

      For example, if one measure a loudspeaker with help of an calibrated R.
      Interesting, it looks like that in specific cases there is no need to
      measure the phase. The amplitude vs. frequency is enough to reconstruct
      the whole circuit parameters. Even the correct phase response can be
      reconstructed.


      Thank you!



      - Henry

      --
      ehydra.dyndns.info
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