Question about full duplex on same frequency with USRP

GNU Radio
1

Hi, I am working on a project using usrp to achieve full duplex(i.e.
transmit
and receive simultaneously) on same frequency. Could anyone tell me if
usrp
can achieve that with one daughterboard or two daughterboards? I have
measured the isolation: one board-30dB, two boards- 60dB. But I cannot
make
it work running my program. The receiver will only receive data after
the
transmitter finishes transmiting, for both one and two daughterboards.
Thank
you.

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2

Hi, I am working on a project using usrp to achieve full duplex(i.e. transmit
and receive simultaneously) on same frequency. Could anyone tell me if usrp
can achieve that with one daughterboard or two daughterboards? I have
measured the isolation: one board-30dB, two boards- 60dB. But I cannot make
it work running my program. The receiver will only receive data after the
transmitter finishes transmiting, for both one and two daughterboards. Thank
you.
You haven’t specified which hardware you’re using, and whether you’re
using UHD, or “classic”, and exactly what it is
you’re doing in your flow-graph.

I can tell you that full-duplex absolutely works in one of the
flow-graphs I’ve been using.

–
Marcus L.
Principal Investigator
Shirleys Bay Radio Astronomy Consortium

3

Hi Marcus,
Thank you for your information. I think I need to state in more detail.
Now I am using two USRPs without UHD with two FLEX 900 daughterboards
inside each USRP. So in total there are four daughterboards. I know it
is impossible to achieve full-duplex on one daughterboard. So I use two
daughterboards in each USRP, one as a TX using TX/RX port, and another
as a RX using RX2 port. I was running two separate programs for Tx and
RX path, but the RX2 port cannot receive data if the TX/RX port does not
finish transmitting. So I changed my flowgraph and build both TX and RX
in a single flowgraph for the top block but still with separate transmit
and receive path. But the probelm still exists. Could you give me some
hints on this?Thank you.

Sincerely,

Chen Dong

Marcus D. Leech wrote in post #1030230:

Hi, I am working on a project using usrp to achieve full duplex(i.e. transmit
and receive simultaneously) on same frequency. Could anyone tell me if usrp
can achieve that with one daughterboard or two daughterboards? I have
measured the isolation: one board-30dB, two boards- 60dB. But I cannot make
it work running my program. The receiver will only receive data after the
transmitter finishes transmiting, for both one and two daughterboards. Thank
you.
You haven’t specified which hardware you’re using, and whether you’re
using UHD, or “classic”, and exactly what it is
you’re doing in your flow-graph.

I can tell you that full-duplex absolutely works in one of the
flow-graphs I’ve been using.

–
Marcus L.
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org