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SDR Soundcard tester

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  • Steve
    Some of you might find this useful :- In ELEKTOR 6 2007 there is a simple circuit based on an 555 chip to test the suitability of soundcards for SDR use. My
    Message 1 of 4 , Dec 5, 2007
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      Some of you might find this useful :-

      In ELEKTOR 6 2007 there is a simple circuit based on an 555 chip to
      test the suitability of soundcards for SDR use. My understanding is
      that Elektor do not allow the exact details of their designs to be
      published so I cannot post it here. However an NE555 generates a 15Khz
      rich in harmonics; the frequency can be varied from about 10-20Khz by
      varying the supply voltage. . At the output of the circuit there are 2
      RC filters one high pass, the other low pass which act as simple phase
      shifters at +45 and -45 degrees respectively i.e 90 degrees in total.
      The I&Q signals so produced feed into the soundcard the behaviour of
      which should be seen using your favourite SDR radio application. The
      circuit only has 8 components.

      You should be able to tell if the soundcard has a stereo line level
      input, anti aliasing and if the sample rate is sufficient from the
      display. All of the hard work here has been done by Burkhard Kainka
      who regularly publishes SDR designs in Elektor. For those of you in
      the colonies Borders may well stock Elektor (they do here in England)
      - Tanners Electronics in Dallas did some while back.
      www.elektor-electronics.co.uk may well be able to tell you how you get
      a back copy of the article. If you read German (which i don't - apart
      from warning of the approach of Spitfires, or to order beer) the
      article seems to have been reproduced at:-

      http://www.elexs.de/iq4.htm#tester

      Hope this helps. Respect is due to Burkhard. As an aside G0BBL, M0PUB
      and I attended a seminar at the Hamfest at Friedricshaven a couple of
      years ago. There was an presentation on SDR so we went. It should have
      been in German but when the presenter found out that we did not speak
      much they gave it in English despite the fact that most of the
      audience was German - and it was standing room only!. Now thats
      hospitality!

      Regards,

      Steve G0XAR
    • T Hoflich
      I posted this in the files section back in May. It could be downloaded free at that time. I built it and it did not work for me and I did not spend much time
      Message 2 of 4 , Dec 5, 2007
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        I posted this in the files section back in May.
        It could be downloaded free at that time.
        I built it and it did not work for me and I did not
        spend much time on it.

        Seems like a neat tool. I hope someone else will give
        it a try

        Tom

        KM5H
        --- Steve <squirrox@...> wrote:

        > Some of you might find this useful :-
        >
        > In ELEKTOR 6 2007 there is a simple circuit based on
        > an 555 chip to
        > test the suitability of soundcards for SDR use. My
        > understanding is
        > that Elektor do not allow the exact details of their
        > designs to be
        > published so I cannot post it here. However an NE555
        > generates a 15Khz
        > rich in harmonics; the frequency can be varied from
        > about 10-20Khz by
        > varying the supply voltage. . At the output of the
        > circuit there are 2
        > RC filters one high pass, the other low pass which
        > act as simple phase
        > shifters at +45 and -45 degrees respectively i.e 90
        > degrees in total.
        > The I&Q signals so produced feed into the soundcard
        > the behaviour of
        > which should be seen using your favourite SDR radio
        > application. The
        > circuit only has 8 components.
        >
        > You should be able to tell if the soundcard has a
        > stereo line level
        > input, anti aliasing and if the sample rate is
        > sufficient from the
        > display. All of the hard work here has been done by
        > Burkhard Kainka
        > who regularly publishes SDR designs in Elektor. For
        > those of you in
        > the colonies Borders may well stock Elektor (they do
        > here in England)
        > - Tanners Electronics in Dallas did some while back.
        > www.elektor-electronics.co.uk may well be able to
        > tell you how you get
        > a back copy of the article. If you read German
        > (which i don't - apart
        > from warning of the approach of Spitfires, or to
        > order beer) the
        > article seems to have been reproduced at:-
        >
        > http://www.elexs.de/iq4.htm#tester
        >
        > Hope this helps. Respect is due to Burkhard. As an
        > aside G0BBL, M0PUB
        > and I attended a seminar at the Hamfest at
        > Friedricshaven a couple of
        > years ago. There was an presentation on SDR so we
        > went. It should have
        > been in German but when the presenter found out that
        > we did not speak
        > much they gave it in English despite the fact that
        > most of the
        > audience was German - and it was standing room
        > only!. Now thats
        > hospitality!
        >
        > Regards,
        >
        > Steve G0XAR
        >
        >
      • Merton Nellis
        Actually, if you have an audio oscillator available all you have to make is the R-C phase shifers for +45 and -45. The R and Xc must be equal to get 45 so the
        Message 3 of 4 , Dec 5, 2007
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          Actually, if you have an audio oscillator available all you have to make is
          the R-C phase shifers for +45 and -45. The R and Xc must be equal to get 45
          so the oscillator freq. can be tweeked as necessary to get the freq. where
          Xc is equal to R. I would think that a sine oscillator would work better
          than the square wave from the 555 oscillator. The 90 deg can also be
          verified on a x-y scope by seeing a circle when the freq. is correct for R =
          Xc. Fun!
          --Mert W0UFO


          ----- Original Message -----
          From: "T Hoflich" <km5h@...>
          To: <softrock40@yahoogroups.com>
          Sent: Wednesday, December 05, 2007 4:38 PM
          Subject: Re: [softrock40] SDR Soundcard tester


          > I posted this in the files section back in May.
          > It could be downloaded free at that time.
          > I built it and it did not work for me and I did not
          > spend much time on it.
          >
          > Seems like a neat tool. I hope someone else will give
          > it a try
          >
          > Tom
          >
          > KM5H
          > --- Steve <squirrox@...> wrote:
          >
          > > Some of you might find this useful :-
          > >
          > > In ELEKTOR 6 2007 there is a simple circuit based on
          > > an 555 chip to
          > > test the suitability of soundcards for SDR use. My
          > > understanding is
          > > that Elektor do not allow the exact details of their
          > > designs to be
          > > published so I cannot post it here. However an NE555
          > > generates a 15Khz
          > > rich in harmonics; the frequency can be varied from
          > > about 10-20Khz by
          > > varying the supply voltage. . At the output of the
          > > circuit there are 2
          > > RC filters one high pass, the other low pass which
          > > act as simple phase
          > > shifters at +45 and -45 degrees respectively i.e 90
          > > degrees in total.
          > > The I&Q signals so produced feed into the soundcard
          > > the behaviour of
          > > which should be seen using your favourite SDR radio
          > > application. The
          > > circuit only has 8 components.
          > >
          > > You should be able to tell if the soundcard has a
          > > stereo line level
          > > input, anti aliasing and if the sample rate is
          > > sufficient from the
          > > display. All of the hard work here has been done by
          > > Burkhard Kainka
          > > who regularly publishes SDR designs in Elektor. For
          > > those of you in
          > > the colonies Borders may well stock Elektor (they do
          > > here in England)
          > > - Tanners Electronics in Dallas did some while back.
          > > www.elektor-electronics.co.uk may well be able to
          > > tell you how you get
          > > a back copy of the article. If you read German
          > > (which i don't - apart
          > > from warning of the approach of Spitfires, or to
          > > order beer) the
          > > article seems to have been reproduced at:-
          > >
          > > http://www.elexs.de/iq4.htm#tester
          > >
          > > Hope this helps. Respect is due to Burkhard. As an
          > > aside G0BBL, M0PUB
          > > and I attended a seminar at the Hamfest at
          > > Friedricshaven a couple of
          > > years ago. There was an presentation on SDR so we
          > > went. It should have
          > > been in German but when the presenter found out that
          > > we did not speak
          > > much they gave it in English despite the fact that
          > > most of the
          > > audience was German - and it was standing room
          > > only!. Now thats
          > > hospitality!
          > >
          > > Regards,
          > >
          > > Steve G0XAR
          > >
          > >
          >
          >
        • Kevin Purcell
          I would have thought a Johnson counter clocked at 4x the 10kHz to 20kHz frequency might have been a better idea. Quadrature guaranteed :-) You could probably
          Message 4 of 4 , Dec 5, 2007
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            I would have thought a Johnson counter clocked at 4x the 10kHz to
            20kHz frequency might have been a better idea.

            Quadrature guaranteed :-)

            You could probably do this with the 555 feeding into 74HC74 or
            74AC74. Or with all 74 series parts (a couple of inverters)?

            The advantage over loopback is it does tell you something useful
            about the soundcards filtering and aliasing problems.

            73 Kevin N7WIM

            On Dec 5, 2007, at 2:38 PM, T Hoflich wrote:

            > I posted this in the files section back in May.
            > It could be downloaded free at that time.
            > I built it and it did not work for me and I did not
            > spend much time on it.
            >
            > Seems like a neat tool. I hope someone else will give
            > it a try
            >
            > Tom
            >
            > KM5H
            > --- Steve <squirrox@...> wrote:
            >
            >> Some of you might find this useful :-
            >>
            >> In ELEKTOR 6 2007 there is a simple circuit based on
            >> an 555 chip to
            >> test the suitability of soundcards for SDR use. My
            >> understanding is
            >> that Elektor do not allow the exact details of their
            >> designs to be
            >> published so I cannot post it here. However an NE555
            >> generates a 15Khz
            >> rich in harmonics; the frequency can be varied from
            >> about 10-20Khz by
            >> varying the supply voltage. . At the output of the
            >> circuit there are 2
            >> RC filters one high pass, the other low pass which
            >> act as simple phase
            >> shifters at +45 and -45 degrees respectively i.e 90
            >> degrees in total.
            >> The I&Q signals so produced feed into the soundcard
            >> the behaviour of
            >> which should be seen using your favourite SDR radio
            >> application. The
            >> circuit only has 8 components.
            >>
            >> You should be able to tell if the soundcard has a
            >> stereo line level
            >> input, anti aliasing and if the sample rate is
            >> sufficient from the
            >> display. All of the hard work here has been done by
            >> Burkhard Kainka
            >> who regularly publishes SDR designs in Elektor. For
            >> those of you in
            >> the colonies Borders may well stock Elektor (they do
            >> here in England)
            >> - Tanners Electronics in Dallas did some while back.
            >> www.elektor-electronics.co.uk may well be able to
            >> tell you how you get
            >> a back copy of the article. If you read German
            >> (which i don't - apart
            >> from warning of the approach of Spitfires, or to
            >> order beer) the
            >> article seems to have been reproduced at:-
            >>
            >> http://www.elexs.de/iq4.htm#tester
            >>
            >> Hope this helps. Respect is due to Burkhard. As an
            >> aside G0BBL, M0PUB
            >> and I attended a seminar at the Hamfest at
            >> Friedricshaven a couple of
            >> years ago. There was an presentation on SDR so we
            >> went. It should have
            >> been in German but when the presenter found out that
            >> we did not speak
            >> much they gave it in English despite the fact that
            >> most of the
            >> audience was German - and it was standing room
            >> only!. Now thats
            >> hospitality!
            >>
            >> Regards,
            >>
            >> Steve G0XAR
            >>
            >>
            >
            >
            >
            >
            > Yahoo! Groups Links
            >
            >
            >

            -...-
            73 DE N7WIM / G8UDP
            Kevin Purcell
            kevinpurcell@...
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