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

[Eric Blossom]

On Sun, Mar 18, 2007 at 02:46:26PM -0400, address@hidden wrote:

> It's a little confusing to me why the Basic TX does not have a
> problem using both the I and Q channel but the Basic RX does.

Actually, there's no problem.  You can get it to do what you want 
by explicitly specifying the rx mux value.

To feed both A side inputs into the DDC 0 as I & Q, do

  u.set_mux(0x10101010)

  /*!
   * \brief Set input mux configuration.
   *
   * This determines which ADC (or constant zero) is connected to 
   * each DDC input.  There are 4 DDCs.  Each has two inputs.
   *
   * <pre>
   * Mux value:
   *
   *    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
   * +-------+-------+-------+-------+-------+-------+-------+-------+
   * |   Q3  |   I3  |   Q2  |   I2  |   Q1  |   I1  |   Q0  |   I0  |
   * +-------+-------+-------+-------+-------+-------+-------+-------+
   *
   * Each 4-bit I field is either 0,1,2,3
   * Each 4-bit Q field is either 0,1,2,3 or 0xf (input is const zero)
   * All Q's must be 0xf or none of them may be 0xf
   * </pre>
   */
  bool set_mux  (int mux);



> It seems to me that the command "-R a:1" would tell the RX_B input to
> receive but not the RX_A input anymore.  I need both the inputs to
> receive data at the same time, as I/Q channels connected to my RF
> front end.  Any insights in how I do this would be much appreciated
> (if my assumption that "-R a:1" would only have the RX_B input
> receive).

> Thanks
> Nick

Eric