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RE: sonogram values

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  • tdigitalmusic
    Thank you Wolf! That all makes sense. I would very much like to incorporate Spectrum Lab into my research project. Part of the project is writing a paper about
    Message 1 of 14 , Sep 7, 2013

      Thank you Wolf! That all makes sense.


      I would very much like to incorporate Spectrum Lab into my research project. Part of the project is writing a paper about it, that will then be read by academic staff in the Electronic Music Unit at the University of Adelaide.


      May I please have your permission to write about Spectrum Lab and how I've used it in my project? I think it will be of interest to my supervisors and peers that software intended for amateur radio use can also be employed in music-related projects. I'd also like to highlight how much can be done with free software, so anyone with a computer should be able to replicate my results.


      Thank you again for all your help,

      Thorsten




      --- In spectrumlabusers@yahoogroups.com, <dl4yhf@...> wrote:

      Hello Thorsten,


      you wrote:
       

      So, am I right in saying that each of the 16384 columns in the exported text file is a frequency bin of 1.346Hz width, and column dB1 is a range of amplitudes (over time) starting at 1.346Hz, column dB2 is a range of amplitudes starting at 2.692Hz, and so on…  (with column dB0 starting at 0Hz).

       

      If I’m right, this may be the closest I can get to producing a range of amplitudes for individual frequencies, which I can then divide by the amount of amplitudes to get an average. It seems to make sense to me.


      The interpretation is almost perfect... maybe with an error (offset) of a half FFT bin width. Quite academic if you don't really need this degree of frequency resolution, but here is the reason:

      The 'first bin' has 'DC' (0 Hz) in the *center*. In fact, if the FFT input was complex, the 'DC' bin would cover frequencies from -half_bin_width to +half_bin_width. Here, since the FFT input (in the time domain) is real, negative frequencies fold back into positive frequencies, but the border between the 'first' and 'second' bin is still at +half_bin_width.

      If the exported FFT file shall contain a header line, the coloums titled "BW_Hz" contains the width of each frequency bin in Hertz, and the column titled "F1_Hz" contains the *center* frequency of the first bin, also in Hertz. If the FFT input is real (not complex), this column contains zero in each line, because that's the *center* frequency of that bin - not the *start* frequency.

      All the best,
         Wolf .

    • wolf_dl4yhf
      Hi Thorsten, ... Yes of course, permission granted . The program isn t restricted to radio-related use at all... that s only my main use. But I also use it
      Message 2 of 14 , Sep 9, 2013
        Hi Thorsten,

        you asked:


        May I please have your permission to write about Spectrum Lab and how I've used it in my project? I think it will be of interest to my supervisors and peers that software intended for amateur radio use can also be employed in music-related projects. I'd also like to highlight how much can be done with free software, so anyone with a computer should be able to replicate my results.



        Yes of course,  "permission granted". The program isn't restricted to radio-related use at all... that's only my main use. But I also use it to listen / study bat sounds, and a few music-related purposes like Mike Oldfield's unintentional recording of Morse code from a UK navy transmitter on 'Tubular Bells' ;-)

        All the best,
          Wolf.

      • df6nm
        Hi John, here s my first attempt on a VOR phase measurement: http://dl.dropboxusercontent.com/u/26404526/SDRsharp_VOR/SDRsharp_VOR.jpg
        Message 3 of 14 , Sep 15, 2013

          Hi John,
           
          here's my first attempt on a VOR phase measurement:
           
          I have used an RTL-SDR stick and a dipole to receive my strongest local VOR (Erlangen 114.9 MHz, about 25 km away so SNR may a bit marginal). Demodulation in SDR# software is set to USB with 16 kHz bandwidth, placing the 30 Hz AM carrier at 1 kHz and the upper 9960 Hz FM-modulated subcarrier at 10.96 kHz. Audio output occurs at 32 kS/s and is fed to SpecLab through Virtual Audio Cable software. SpecLab runs an AM demodulator on the left channel and an FM demodulator on the right. The phase between the two 30 Hz outputs is measured by the colour-DF spectrogram function which then outputs azimuth directly. I have not checked whether the RDF measurement should be clockwise or counterclockwise, and whether there should be an angular offset. Note that this technique will probably only work for standard VOR's with a pure carrier, and would have to be modified for a Doppler-type D-VOR.

          BTW I'm having a hard time reading the new Yahoo "neo" website format. Seems much slower than before, and on a small screen, between all the title bars and ads there's hardly any room left for contents.

          Best 73,
           
          Markus (DF6NM)
          http://df6nm.de

          --- In SpectrumLabUsers@yahoogroups.com, <spectrumlabusers@yahoogroups.com> wrote:

          Hello to you all,

          I wonder if one can use SL to decode the phase difference of a VOR
          signal versus our local stn and give the angle or a data which can help
          us to deduct an angle ?

          any trick ?

          best regards

          John F5VLB
        • wolf_dl4yhf
          Greetings John and all, Below is a copy of the response from Markus DF6NM to John s original question. Like myself, Markus is having trouble with Yahoo s new
          Message 4 of 14 , Sep 18, 2013
            Greetings John and all,

            Below is a copy of the response from Markus DF6NM to John's original question.

            Like myself, Markus is having trouble with Yahoo's new "Neo" format .

            Unfortunately, once switched to the stupid new screen-space-wasting 'Neo'-format, there is no way back so beware.
            For myself, the Yahoo website becomes more and more unusable, and I only send + receive messages via email, in pure text format.

            All the best,
             Wolf DL4YHF .



            Original message by DF6NM below.



            ______________________________
            Re: VOR decoding
             
            Hi John,
             
            here's my first attempt on a VOR phase measurement:
             
             
            I have used an RTL-SDR stick and a dipole to receive my strongest local VOR (Erlangen 114.9 MHz, about 25 km away so SNR may a bit marginal). Demodulation in SDR# software is set to USB with 16 kHz bandwidth, placing the 30 Hz AM carrier at 1 kHz and the upper 9960 Hz FM-modulated subcarrier at 10.96 kHz. Audio output occurs at 32 kS/s and is fed to SpecLab through Virtual Audio Cable software. SpecLab runs an AM demodulator on the left channel and an FM demodulator on the right. The phase between the two 30 Hz outputs is measured by the colour-DF spectrogram function which then outputs azimuth directly. I have not checked whether the RDF measurement should be clockwise or counterclockwise, and whether there should be an angular offset. Note that this technique will probably only work for standard VOR's with a pure carrier, and would have to be modified for a Doppler-type D-VOR.
             

            BTW I'm having a hard time reading the new Yahoo "neo" website format. Seems much slower than before, and on a small screen, between all the title bars and ads there's hardly any room left for contents.
             

            Best 73,
             
            Markus (DF6NM)
            http://df6nm.de
             

            Re: [SpectrumLabUsers] VOR decoding  (1723)Reply
            Jean Marie Polard
            Sep 06
             
            Hello to you all,
             
            I wonder if one can use SL to decode the phase difference of a VOR
            signal versus our local stn and give the angle or a data which can help
            us to deduct an angle ?
             
            any trick ?
             
            best regards
             
            John F5VLB
             
             
          • Jurgen Bartels
            ... Me too. And I am happy with it. It works well, and is just so easy to use. I never bothered with their web site Jurgen
            Message 5 of 14 , Sep 18, 2013
              > For myself, theYahoowebsite becomesmore and moreunusable, and I only
              > send + receive messages via email, in pure text format.

              Me too. And I am happy with it.
              It works well, and is just so easy to use. I never bothered with their web site



              Jurgen
            • f5vlb_john
              Hi Markus, I lost your email, can you contact me again at f5vlb@kermaz.com tks and best 73 s John
              Message 6 of 14 , Sep 26, 2014
                Hi Markus, I lost your email, can you contact me again at f5vlb@...

                tks and best 73's

                John
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