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Re: [Discuss-gnuradio] Simultaneous TX/RX Sample Code for RFX (FLEX) 400
From: |
Eric Blossom |
Subject: |
Re: [Discuss-gnuradio] Simultaneous TX/RX Sample Code for RFX (FLEX) 400 |
Date: |
Sat, 20 May 2006 21:11:53 -0700 |
User-agent: |
Mutt/1.5.9i |
On Sat, May 20, 2006 at 08:59:00PM -0700, rdmiller wrote:
>
> Eric,
>
> Thank you very much for the reply. I noticed that I was actually modifying
> a very old version of usrp_rx_cfile.py (found at
> http://www.koders.com/python/fidB649E66943F7649C67371CB015D6E5ACAE276523.aspx).
>
> I've taken a look at the latest version from cvs and have a question
> regarding the proper way to add the call to select_rx_antenna( ). It
> appears that the mux value is set based upon user input or another method,
> and that this may result in improper operation using RX2. I've tried
> setting the rx_subdev_spec to 'RX2' from the command line argument with
> error. The message is to use 'A', 'A:0', or 'A:1' when using the A side of
> the usrp. When trying 'A:1', an error also results. So, when I run the
> code I am using 'A:0' as the input. I am therefore fearful of having bad
> mux values even though the modified code (listed below) runs without error
> in terms of creating the data file. My question is whether or not there is
> a simple alteration to the code below that will result in using RX2 for
> receiving data while transmitting simultaneously from RX/TX?
The subdevice spec has to do with selecting either the daughterboard
on the A or B side. It has nothing to do with the selection of the
TX/RX vs RX2 antenna port. The mux is set up depending on the A vs B
selection.
Your code looks right. Sorry, not near a USRP to test it right now.
> Although I am aware that the signal will need to be attenuated severely, I
> am unsure what the RF front end of the RFX-400 is spec'd for. With a 20 dBm
> signal at the TX, I am planning to use anywhere from 40 to 60 dB of
> attenuation. I believe this will give me a -20 to -40 dBm signal at RX2.
> This should be acceptable, right? Thanks again for your help, it is much
> appreciated.
I'm not sure. Matt's the guy to answer this (unless it's already on
the daughterboard data sheet). He's at the Dayton Hamvention now ;)
Eric