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Re: [Discuss-gnuradio] Question about Basic TX/RX boards, the I, Q
From: |
njm25 |
Subject: |
Re: [Discuss-gnuradio] Question about Basic TX/RX boards, the I, Q |
Date: |
Tue, 03 Apr 2007 09:50:20 -0400 |
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
> >
>
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