Re: [Discuss-gnuradio] uhd running parallel tx/rx flowgraphs

On 02/26/2012 02:29 PM, Apurv Bhartia wrote:

Its an XCVR2450, but I do *not* start any 'packet' transmissions. All I do, is to start both the flowgraphs, and just listen for packets.

In which case, the TX side is running--even if you aren't sending any *data* bits, it's still transmitting, and blocking the receiver.

You'll have to get more sophisticated about half-duplex flow management, using tagging to tell UHD to turn on/off the TX side.

Josh probably has better words of wisdom on this than I.

On Sun, Feb 26, 2012 at 6:13 AM, Andre Puschmann <andre.puschmann@tu-ilmenau.de> wrote:

On 02/26/2012 10:38 AM, Apurv Bhartia wrote:
> Hi,
>
> I'm running Ubuntu 11.10 + UHD 003.004.000 + USRP2.
>
> I'm trying to run a transceiver script for OFDM, which has both the tx
> and rx flowgraphs (very similar to tunnel.py except the TUN interface).
> But, I can't seem to receive anything successfully in that case. Even
> the preamble correlation fails, it barely sees anything substantial in
> the air at the RF end.
> On the other hand, if I just disable the uhd_transmitter in the script,
> the receiver then works just about great.
>
> I've run the transceiver script earlier on USRP2 with the eth driver -
> could it be something to do with the UHD? Is it possible that the
> transmitter is in some way locking the receiver?
>
> P.S: Individually, tx and rx work just fine.

You did not mention which daughterboard you're using. If it's the
XCVR2450 db and you continuously transmit you sort of block your
receiver indeed. That's because the XCVR2450 is only half-duplex.

-Andre

 
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