[USRP-users] Full Duplex vs. Half Duplex operation?
radiogeek381 at gmail.com
Thu Oct 23 20:32:53 EDT 2014
Posting to the list was the key to finding the solution.
Apparently, libuhd/FPGA determines that we are in "full duplex" mode when
there is an
active (that is to say, extant) tx_streamer alive at the same time we have
an extant rx_streamer.
It doesn't matter if anything is being set to the streamer, its mere
existence (along with
an rx_streamer) will trigger the condition.
As you said, the ATR (automatic-transmit-receive) switch in the GPIO
register is pretty
smart. If you are in full dux, it won't connect the RX input to the TX
bad things will happen. So, to build a transceiver that uses the TX/RX
port for the antenna,
one needs to destroy any active tx_streamers while in RX mode, and recreate
before initiating a new transmission.
So, the rule is:
foo = usrp->get_tx_stream(stream_args);
creates a streamer. The radio will be in the ATR_REG_FULL_DUPLEX (if there
an rx_streamer in existence) or ATR_REG_TX_ONLY (if not.)
destroy the tx_streamer
(like this?) foo->~tx_streamer(); // I'm sure there is a better way
and the mode is either ATR_REG_RX_ONLY (if an rx_streamer is alive) or
The key to finding something yourself is to ask someone else where it
On Thu, Oct 23, 2014 at 7:47 PM, Ian Buckley <ianb at ionconcepts.com> wrote:
> ---- snip -----
> The gist of this is that in your case either: a) For some reason the
> ATR-GPIO has not been programmed by UHD to select the correct SMA or b) The
> USRP is not in the state you think it is (RX vs Full-Duplex)
> Make sense?
> On Oct 23, 2014, at 4:10 PM, Radio User via USRP-users <
> usrp-users at lists.ettus.com> wrote:
> Fellow USRPers..
> ---- snip ----
> USRP-users mailing list
> USRP-users at lists.ettus.com
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