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

[njm25]

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 Blossom <address@hidden>
Date: Tuesday, March 20, 2007 10:15 am
Subject: Re: [Discuss-gnuradio] Question about Basic TX/RX boards, the I, Q

> 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
>