[Discuss-gnuradio] How to reconfigure automatically the channel used to received data in USRPs

[Lebowski80]

Hello everyone,

Before to explain my problem I give some technical information about my
hardaware. I'm using USRPs v1 and the boards integrated are XCVR2450
Transceivers.  

I'm using the script usrp_spectrum_sense.py in a USRP (called USRP1) to make
sensing in the ISM band, after a few seconds it sends to another USRP
(Called USRP2) a free sensed channel on the central frequency 2484 MHz.
USRP2 listens to the channel 2484 MHz through the script benchmark_rx.py and
it can properly receive the free ISM channel sent by USRP1. Then, I want to
use the USRP2 to receive data from another USRP (called USRP3) that uses the
script benchmark_tx.py.

In the script benchmark_rx.py (used by USRP2) that listens to channel 2484
MHz I want to run another script that I called benchmark_rxr.py that waits
for data sent by USRP3 to be received in the free ISM channel sent by USRP1.

Relevant line of the code in the script benchmark_rx.py is attached below:

p = Popen('python benchmark_rxr.py', shell =  True)

While this is the error that I get:

usrp_open_interface:usb_claim_interface: failed interface 2
could not claim interface 2: Device or resource busy
usrp_basic_rx: can't open rx interface
Traceback (most recent call last):
  File "benchmark_rxr.py", line 153, in <module>
    main()
  File "benchmark_rxr.py", line 138, in main
    tb = my_top_block(demods[options.modulation], mods[options.modulation],
rx_callback, options)
  File "benchmark_rxr.py", line 46, in __init__
    self.rxpath = usrp_receive_path.usrp_receive_path(demodulator,
rx_callback, options)
  File "/opt/gnuradio/gnuradio-examples/python/usrp/usrp_receive_path.py",
line 65, in __init__
    self._setup_usrp_source(options)
  File "/opt/gnuradio/gnuradio-examples/python/usrp/usrp_receive_path.py",
line 78, in _setup_usrp_source
    self.u = usrp_options.create_usrp_source(options)
  File "/usr/local/lib/python2.6/dist-packages/gnuradio/usrp_options.py",
line 88, in create_usrp_source
    gain=options.rx_gain,
  File
"/usr/local/lib/python2.6/dist-packages/gnuradio/blks2impl/generic_usrp.py",
line 138, in __init__
    _generic_usrp_base.__init__(self, **kwargs)
  File
"/usr/local/lib/python2.6/dist-packages/gnuradio/blks2impl/generic_usrp.py",
line 63, in __init__
    except: raise Exception, 'Failed to automatically setup a usrp device.'
Exception: Failed to automatically setup a usrp device.

I read different post with this problem such as "Full duplex and half duplex
does not work" and "help: cannot send after transport endpoint shutdown" but
I could not solve the problem yet. I need to close the reception in 2484 MHz
channel for a new reception in another channel in USRP2. The only way to do
that seems to close the port manually (i.e. pressing ctrl+c) but I want to
do that by code. I tried different things before the line "p = Popen('python
benchmark_rxr.py', shell =  True)" such as "id_process = os.getpid()" and
"os.killpg(id_process, 2)", or by "tb.lock()" and "tb.unlock" and so on, but
nothing helped me, I keep obtaining the same error. I don't know what to do
else, can I change by code reception frequency in USRP2? Any advice will be
welcome, thanks a lot!

Regards 


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