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

[njm25]

I can't get the output to the fm_tx_2_daughterbaords.py example to work.  I am 
testing with 2 complex signals and on each signal, the I channel is a sinusoid 
and the Q channel is a sinusoid of a different frequency.  I have connected 
each of the 4 SMA connectors from the 2 Basic TX daughterboards to a different 
channel on an oscope.  I expect to see a sinusoid on each channel but that is 
not the case.  I see some weird waveform on the different channels on the 
oscope.  Originally I didn't think the TX mux was set correct because the 
comments at the beginning of the example says that it transmits SSB (USB) and 
that is not what I'm looking for.  I want each of the 4 different waveforms (2 
sines on the I's and 2 sines on the Q's, all with different frequencies) to 
come out of the 4 SMA connectors.  Any help would be greatly appreciated.

Thanks,
Nick

----- Original Message -----
From: Eric Blossom <address@hidden>
Date: Wednesday, March 21, 2007 9:45 pm
Subject: Re: [Discuss-gnuradio] Question about Basic TX/RX boards, the I, Q

> 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
>