Re: [Discuss-gnuradio] Suse10.1 walkthrough and a question concerning crosstalk

[Mark Sullivan]

Eric,

As an additional experiment I hacked multi_file.py in the multi-antenna
folder so that the multiplexor was set to channel 0 for all four "I"
inputs; with a carrier injected into channel 1, I saw identical
leakage. I then changed the mux setting to channel 1 for all "I" and
saw the injected carrier. This isn't sounding like software.

Best regards,

Mark Sullivan

On 9/22/06, Eric Blossom <address@hidden> wrote:

On Fri, Sep 22, 2006 at 05:38:54PM -0400, Mark Sullivan wrote:
> When I inject a signal at a -45 dBm level on the "RX-B" sma connector on a
> Basic RX daughtercard, I see a copy of the signal on the "RX-A" side when I
> use usrp_fft.py. The level is 10-20 dB below that of what I see if I move
> the signal from "RX-B" to "RX-A," but this seems like too much coupling.
> Using a 50 ohm termination on the unconnected sma connector helps a little
> bit. I see no copy of the signal from either input of the other Basic RX
> daughtercard. Any thoghts, anyone?
>
> Best regards,
>
> Mark Sullivan


Hi Mark,


There's a chance that the code that determines the rx digital mux
setting isn't handling this case properly.


Assuming that the Basic Rx is on the "A" side, please try this:

  $ usrp_fft.py -R a:0 -f <freq>

and try moving the test signal from RX-A to RX-B


and this:

  $ usrp-fft.py -R a:1 -f <freq>

and move the test signal from RX-A to RX-B

What happens?

Thanks,
Eric