Re: Question about Basic TX/RX boards, the I, Q

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.

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?

Thanks
Nick

----- Original Message -----
From: Eric B. [email protected]
Date: Tuesday, March 20, 2007 10:15 am
Subject: Re: [Discuss-gnuradio] Question about Basic TX/RX boards, the
I, Q

On Wed, Mar 21, 2007 at 05:31:36PM -0400, [email protected] 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.

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) :wink:

It is different, it’s the Tx mux, not the Rx mux…

/*!

  • \brief Set output mux configuration.
  • 
    
  • 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

*/
bool set_mux (int mux);

Thanks
Nick

You’re welcome!

Eric