[USRP-users] Problems using Airprobe with USRP1

Thomas Tsou tom at tsou.cc
Fri Apr 12 14:48:22 EDT 2013


On Thu, Apr 11, 2013 at 12:39 PM, GSM Research
<gsm.research.group at gmail.com> wrote:
> We are trying to use uhd_rx_cfile for the capture.  When running the
> program, it does appear to be capturing data (at least a large file is
> created), but we are unable to decode the datafile that is created.
>
> A typical run of uhd_rx_cfile that we have tried (for ARFCN 800) is:
>     root# uhd_rx_cfile -g 52 -N 2000000 -f 1987800000 output.cfile

As previously stated, Airprobe assumes a decimation of 112 on a 64 MHz
clocked USRP1. The decimation rate itself isn't relevant in
gsm-receive.py, just sample rate. I ran the following on B100
similarly clocked at 64 MHz.

$ uhd_rx_cfile.py --samp-rate 571428.571429 -f 1978e6 capture.dat

$ ./go.sh capture.dat
>>> gr_fir_ccc: using SSE
>>> gr_fir_ccf: using SSE
Key: '0000000000000000'
Configuration: ''
  No configuration set.
configure_receiver
gr_buffer::allocate_buffer: warning: tried to allocate
   115 items of size 568. Due to alignment requirements
   512 were allocated.  If this isn't OK, consider padding
   your structure to a power-of-two bytes.
   On this platform, our allocation granularity is 4096 bytes.
2336549 0: 31 06 21 20 08 39 01 62 50 46 91 16 84 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b
2336553 0: 15 06 21 00 01 f0 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b
2336559 0: 15 06 21 00 01 f0 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b
2336563 0: 49 06 22 a0 0b 5a d9 4d f8 59 15 2d 17 05 f4 c4 5a 36 4d cb 2b 2b 2b
...

  Thomas




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