[USRP-users] Problem of SBX board to support full-duplex communications.

Alex Zhang cingular.alex at gmail.com
Thu Jun 21 02:30:09 EDT 2012


Hi,

As declared by SBX applications nodes, it supports full-duplex, which means
the transceiver can perform transmission and receiving at the same time.
However, within my application, I found the SBX is working as half-duplex,
even I set the antenna as RX2 for receiver, and TX/RX for transmitter.

In my case, I am setting up a point to point link and try the double-way
communcations, i.e, A send a request to B, and B should send a reply back
to B.
The observed behavior is: B can only send the reply by a delay to ensure
the A receive this reply correctly. I am suspecting this is due to the
half-duplex
switching time at A. My test result shows that the B should delay 9ms after
it gets request from A and then the reply can be delivered to A safely.
Otherwise,
A can not receive this reply or the received packet fails in CRC check.
In GNURadio community, many guys complains the PING test fails, due to the
ARP query failure. I add the delay to the ARP reply and this PING test
passed.
So I believe there is some problem in duplex, either caused by incorrect
setting or board issue.

Is there anything I missed, to get the SBX board supporting full-duplex?

-- 

Alex,
*Dreams can come true – just believe.*
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