Re: [Discuss-gnuradio] Question about Basic TX/RX boards, the I, Q

[Eric Blossom]

On Wed, Mar 21, 2007 at 05:31:36PM -0400, address@hidden wrote:

> Thanks again for the help.  I think I better understand how to set
> the RX mux.  I am now working on the multi_file.py example to
> receive using 2 daughterboards on the same USRP.  I want to do the
> same type of thing using 2 antennas where RX-A and RX-B (on side A)
> will receive signal 1's I and Q and RX-A and RX-B (on side B) will
> receive signal 2's I and Q.  If my understanding is correct, I would
> set the mux to (0x32103210).  Let me know if this is not correct.

Correct.

> My question now comes on the TX side.  I don't quite understand how
> to set the TX mux.  I want to transmit using 2 daughterboards on 1
> USRP so I am using the fm_tx_2_daughterboards.py example.  I want
> daughterboard 1 to transmit the I (RX-A) and Q (RX-B) of signal 1
> and daughterboard 2 to transmit the I (RX-A) and Q (RX-B) of signal
> 2.  This example uses the command:
> 
> self.u.set_mux(0xba98)
> 
> which I don't think is right for what I want to do, but I don't
> really understand how to set the TX mux in the same way I understand
> how to set the RX mux (it seems to be different).  How would I set
> the TX mux to do what I want?

  self.u.set_mux(0xba98)   ;)

It is different, it's the Tx mux, not the Rx mux...

  /*!
   * \brief Set output mux configuration.
   *
   * <pre>
   *     3                   2                   1                       
   *   1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
   *  +-------------------------------+-------+-------+-------+-------+
   *  |                               | DAC3  | DAC2  | DAC1  |  DAC0 |
   *  +-------------------------------+-------+-------+-------+-------+
   * 
   *  There are two interpolators with complex inputs and outputs.
   *  There are four DACs.
   * 
   *  Each 4-bit DACx field specifies the source for the DAC and
   *  whether or not that DAC is enabled.  Each subfield is coded
   *  like this: 
   * 
   *     3 2 1 0
   *    +-+-----+
   *    |E|  N  |
   *    +-+-----+
   * 
   *  Where E is set if the DAC is enabled, and N specifies which
   *  interpolator output is connected to this DAC.
   * 
   *   N   which interp output
   *  ---  -------------------
   *   0   chan 0 I
   *   1   chan 0 Q
   *   2   chan 1 I
   *   3   chan 1 Q
   * </pre>
   */
  bool set_mux  (int mux);


> Thanks
> Nick

You're welcome!

Eric