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Re: decoding BC station with SDR - changing the LO or filter

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  • hm2612
    dear graham many thanks for your reply. i was thinking about a hardware solution too. once i built a frequency counter with an atmel atmega chip. there i could
    Message 1 of 8 , Jan 31, 2012
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      dear graham

      many thanks for your reply.
      i was thinking about a hardware solution too. once i built a frequency counter with an atmel atmega chip. there i could change the source code to show only the fourth part of the measured frequency. as external LO for the SDR i am using the FA-NWT01 ( funkamateur netzwerk tester ) this one has a very stable QRG.

      the disadvantage of such a hardware solution is the fact, that receiving at the LO isn't possible, as this is the 0 Hz point in the waterfall. therefore i have to use an offset. this could also be easy kept in mind but the configuration of the spectrum lab must reflect this too.

      but finally i want to receive VLF. the frequency steps are there much smaller. therefore i am looking for an easy solution with the software spectrum lab. to receive the BC stations in the LF band is just to play with it, to learn and to get strong signals.

      73
      hans
      oe1smc

      --




      --- In SpectrumLabUsers@yahoogroups.com, Graham Mcleod <g8pha@...> wrote:
      >
      > One Hardware solution is to use a VCO or VFO as the external LO, and add a Divide-by-4 before
      > feeding it into a Frequency Counter. Then it will Directly read the Centre Frequency being received.
      > Building stable oscillators at HF is of course a skill in itself, or add a Phase Lock Loop, etc.
      > One way is to cut down the Frequency Coverage ratio, perhaps using several switched ocillators...
      >  
      > I too am interested in software/SL answers to this... Gra.
      >
    • hm2612
      btw, with slide control on the right side there is the possibility to change the frequency of the LO in 1 Hz steps using the mouse wheel. is there a way to
      Message 2 of 8 , Feb 2, 2012
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        btw, with slide control on the right side there is the possibility to change the frequency of the LO in 1 Hz steps using the mouse wheel. is there a way to change the step size ?
        for example 100 Hz. 10 Hz could be done with clicking the left mouse button ( for a right hand operator )

        73
        oe1smc

        --


        --- In SpectrumLabUsers@yahoogroups.com, "hm2612" <hm2612@...> wrote:
        >
        >
        > dear graham
        >
        > many thanks for your reply.
        > i was thinking about a hardware solution too. once i built a frequency counter with an atmel atmega chip. there i could change the source code to show only the fourth part of the measured frequency. as external LO for the SDR i am using the FA-NWT01 ( funkamateur netzwerk tester ) this one has a very stable QRG.
        >
        > the disadvantage of such a hardware solution is the fact, that receiving at the LO isn't possible, as this is the 0 Hz point in the waterfall. therefore i have to use an offset. this could also be easy kept in mind but the configuration of the spectrum lab must reflect this too.
        >
        > but finally i want to receive VLF. the frequency steps are there much smaller. therefore i am looking for an easy solution with the software spectrum lab. to receive the BC stations in the LF band is just to play with it, to learn and to get strong signals.
        >
        > 73
        > hans
        > oe1smc
        >
        > --
        >
        >
        >
        >
        > --- In SpectrumLabUsers@yahoogroups.com, Graham Mcleod <g8pha@> wrote:
        > >
        > > One Hardware solution is to use a VCO or VFO as the external LO, and add a Divide-by-4 before
        > > feeding it into a Frequency Counter. Then it will Directly read the Centre Frequency being received.
        > > Building stable oscillators at HF is of course a skill in itself, or add a Phase Lock Loop, etc.
        > > One way is to cut down the Frequency Coverage ratio, perhaps using several switched ocillators...
        > >  
        > > I too am interested in software/SL answers to this... Gra.
        > >
        >
      • Jurgen Bartels
        ... These things are surely not created to replace a fancy user interface. So why don t your write your own little app doing all that and send the values to
        Message 3 of 8 , Feb 2, 2012
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          > btw, with slide control on the right side there is the possibility to change
          > the frequency of the LO in 1 Hz steps using the mouse wheel. is there a way to
          > change the step size ?

          These things are surely not created to replace a fancy user interface.
          So why don't your write your own little app doing all that and send the values
          to SpecLab?
          It's so simple thanks to SpecLab's well thought-out command interpreter

          I did excactly that with my StationList program

          Watch the video "OIRT FM-Session ..." in
          http://dx.3sdesign.de/fm_bandwith_talk.htm

          All frequency settings are sent to SpecLab's cmd interpreter




          Jurgen Bartels Suellwarden, N. Germany
          Antennas hor.: 45-87MHz: 11-ele, FM: 15.11, Band-III:13-ele, UHF:48-ele,
          TV: Winradio G305 / Fly2000 + video noise filter & variable IF BW
          FM: Downconverter + Perseus + Speclab as WFM demod.
          MW: 90m bev 220°, 30 x 4m EWE 320° with JB-terminator, Winradio & Perseus
          300m staggered beverages 320° http://dx.3sdesign.de/staggered_beverage.htm
          http://zeiterfassung.3sdesign.de/station_list.htm
        • Graham Mcleod
          Hans, Certain kinds of FFT (& Hardware) can output a -ve & +ve Frequency spectrum, with Zero at the centre. If downmixed, this translates as LO frequency
          Message 4 of 8 , Feb 2, 2012
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            Hans,
            Certain kinds of FFT (& Hardware) can output a -ve & +ve
            Frequency spectrum, with Zero at the centre.
            If downmixed, this translates as LO frequency +/- Separated.
            Upper and Lower Sidebands, with Image Rejection.
            As a new user, I haven't yet discovered if SL can do this,
            or how to configure it for this. However this ought to yield
            reception through "Zero Frequency", with DC coupled ADC's....
            Or a 40Hz central notch, with 20Hz HPF Audio Soundcards?. Gra.
          • wolf_dl4yhf
            ... That s exactly what the FFT s complex input option for the is for:. http://www.qsl.net/dl4yhf/speclab/settings.htm#fft_settings It comes in two flavours:
            Message 5 of 8 , Feb 2, 2012
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              Am 02.02.2012 12:50, schrieb Graham Mcleod:
               
              Hans,
              Certain kinds of FFT (& Hardware) can output a -ve & +ve
              Frequency spectrum, with Zero at the centre.
              If downmixed, this translates as LO frequency +/- Separated.
              Upper and Lower Sidebands, with Image Rejection.
              As a new user, I haven't yet discovered if SL can do this,
              or how to configure it for this.

              That's exactly what the FFT's 'complex input' option for the is for:.

              http://www.qsl.net/dl4yhf/speclab/settings.htm#fft_settings

              It comes in two flavours: with separate input channels (for external quadrature mixers), and with internal frequency shift (for single-channel input, in this case the quadrature mixing is done by software).




              However this ought to yield
              reception through "Zero Frequency", with DC coupled ADC's....
              Or a 40Hz central notch, with 20Hz HPF Audio Soundcards?. Gra.

            • hm2612
              dear all many thanks for the reply. jurgen, i will try it to use the command interpreter. 73 de hans oe1smc --
              Message 6 of 8 , Feb 6, 2012
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                dear all

                many thanks for the reply.
                jurgen, i will try it to use the command interpreter.

                73 de hans
                oe1smc

                --



                --- In SpectrumLabUsers@yahoogroups.com, wolf_dl4yhf <dl4yhf@...> wrote:
                >
                >
                > Am 02.02.2012 12:50, schrieb Graham Mcleod:
                > > Hans,
                > > Certain kinds of FFT (& Hardware) can output a -ve & +ve
                > > Frequency spectrum, with Zero at the centre.
                > > If downmixed, this translates as LO frequency +/- Separated.
                > > Upper and Lower Sidebands, with Image Rejection.
                > > As a new user, I haven't yet discovered if SL can do this,
                > > or how to configure it for this.
                >
                > That's exactly what the FFT's 'complex input' option for the is for:.
                >
                > http://www.qsl.net/dl4yhf/speclab/settings.htm#fft_settings
                >
                > It comes in two flavours: with separate input channels (for external
                > quadrature mixers), and with internal frequency shift (for
                > single-channel input, in this case the quadrature mixing is done by
                > software).
                >
                >
                >
                >
                > > However this ought to yield
                > > reception through "Zero Frequency", with DC coupled ADC's....
                > > Or a 40Hz central notch, with 20Hz HPF Audio Soundcards?. Gra.
                > >
                >
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