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Re: SoftRock and PowerSDR tx mode

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  • joe price
    ... with ... device ... a ... I ve been testing Guido s modifyied SDR code and here are my results along with a few comments. When using two soundcards and VAC
    Message 1 of 9 , Aug 3, 2006
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      --- In softrock40@yahoogroups.com, "joe price" <joeprice@...> wrote:
      > --- In softrock40@yahoogroups.com, Guido <threeme3@> wrote:
      > >
      > > Good afternoon Onno, All,
      > >
      > > I have modified PowerSDR a bit:
      > >
      > > PowerSDR Beta Release 1.6.3 (Rev 585) has been extended for use
      > > SoftRock40 model. Features include:
      > >
      > > - IQ Sample Correction
      > > Necessary to correct the left-right sample event when a sound
      > > introduce a delay in one of the channels. This applies for sound
      > chips like
      > > PCM290x, WM8775ED5 (as used in Creative Soundblaster Live! 24 bit
      > internal
      > > sound card).
      > >
      > > - IQ Output when transmitting
      > > The SoftRock40 model can only Receive Only. However, to enable
      > > experimentation with a SoftRock40-alike transmitter, now it is
      > possible to
      > > generate IQ signals when a PTT/MOX button is pressed. Like in RX,
      > the IQ
      > > signals uses a variable IF frequency which is the VFO frequency
      > relative to
      > > the "Center Freq".
      > >
      > > - Dual soundcard support
      > > To enable the use of cheap soundcards, now it is possible to use
      > specific
      > > soundcard dedicated for TX and RX, in combination with another
      > soundcard
      > > dedicated for Microphone input and Speaker output.
      > >
      > > Find more of this at http://powersdr-sr40.sourceforge.net
      > >
      > > 73, Guido.

      I've been testing Guido's modifyied SDR code and here are my results
      along with a few comments.

      When using two soundcards and VAC although it worked, there is a lot
      of delay (latency) between speaking into the MIC and I/Q output from
      soundcard. I was curious about this and I Bit the bullet and purchased
      a Delta 44 card. When using PowerSDR's setup for Delta the latency is
      much less. But whichever scheme you choose the tx I/Q out works.
      The tx I/Q frequency is determined by where you drag the receive
      signal if you have it at cener then the output will be at audio
      if the signal is draged 15khz off then the tx I/Q signal is at 15khz.
      This is exactly the same as the receive I/Q works. this only works
      with voice modulation (ssb ect.) it will not work in the CW mode.
      because the software (PowerSDR) generates a keyed signal just offset
      from Zero slightly.
      The bottom line about this is Guido's current code can only be used
      in the SSB mode. As it stands transmitt I/Q will follow receive I/Q
      frequency. When going to CW transmitt the tx I/Q will be near zero
      and not match the received frequency. In the Flexradio the receive
      is offset about 11khx to get away from noise at center frequency
      and the tx is a zero.
      I'm not sure if the tx I/Q balance will hold over the entire 96khz
      tuning range this needs to be checked. I would prefer that both
      tx and rx frequency both be offset at 11khz the would allow I/Q
      balance to remain fixed at one frequency and by using a superhet
      based system with WA6UFQ's DDS pc control software to do tuning
      and any offset.
      One final note when using the PowerSDR software external control
      such as PTT and KEYER appear on the printer port so if you where to
      use both PowerSDR and WA6UFQ's dds program at the same time you will
      need two printer ports.

      73 Joe wa9cgz
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