On 07/04/2019 11:14 PM, Tom McDermott via USRP-users wrote:
I am trying to use a B205mini in half-duplex mode through the TX/RX
connector
from a GRC flowgraph. Gnuradio 3.7.13.4. Very slow switching,
manually implemented.
The flowgraph implements a simple half-duplex transceiver. In order to
switch
the TX/RX antenna switch, I am starting and stopping samples to the
USRP sink
using the Copy block. When the Copy block is enabled it passes
samples to the USRP sink,
and when disabled it does not copy samples to the USRP sink.
If the Copy block is statically enabled, then the USRP transmits (RED
led 'On' for TX/RX)
continuously without any underruns.
If the Copy is statically disabled, then USRP goes into receive mode
(GREEN led 'On' for TX/RX)
and stays in that mode.
So far so good.
However if I toggle the enable/disable on the copy block to disable
the TX/RX switches as it should
from red to green, but after I re-enable the Copy block and leave it
enabled, the TX/RX LED goes red
for awhile, then rapidly flashes red/green/red etc. while printing
UUUUUUU on the GRC console, then
goes RED for about 5 seconds without underruns, then flashes RED/GREEN
rapidly for 5 or 10 seconds
and underruns, back and forth ad infinitum.
So Copy appears not to be a good way to implement T/R switching.
There is a message port on the USRP sink block. Can this be used to
implement T/R switching?
Is there some place that the messages that this port accepts defined?
I cannot seem to find
the syntax for the message definitions in the USRP documentation, so I
must be looking in the wrong place.
-- Tom, N5EG
There's some documentation here:
https://www.gnuradio.org/doc/doxygen/classgr_1_1uhd_1_1usrp__sink.html
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