[USRP-users] Most performant way to save samples to disk from a B200?

Hans Van Ingelgom hvaningelgom at gmail.com
Tue Oct 21 01:14:55 EDT 2014


I just did a test with uhd_rx_cfile, but when I try to read these samples
back into grc, I stumble upon a road block: I can read samples as short,
but not complex shorts. Maybe an extension to this block is appropriate?

On Tue, Oct 21, 2014 at 5:47 AM, Marcus D. Leech via USRP-users <
usrp-users at lists.ettus.com> wrote:

>  On 10/20/2014 11:42 PM, Hans Van Ingelgom via USRP-users wrote:
>
> Hello,
>
>  I want to record samples to disk from a B200. I could make a flowgraph
> in gnuradio-companion, but that will save floating point values. Is there a
> more efficient way to store samples, as the raw format is only 12 bits? Any
> tips on getting the most performance?
>
>  (I have been playing with this thing for a few months now, and "drinking
> from a firehose" is a saying that really applies to that piece of hardware).
>
>  Thanks,
> Hans Van Ingelgom
>
>
> _______________________________________________
> USRP-users mailing listUSRP-users at lists.ettus.comhttp://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>
>  Here's the --help output for rx_samples_to_file:
>
> ./rx_samples_to_file --help
> linux; GNU C++ version 4.7.2 20121109 (Red Hat 4.7.2-8); Boost_105000;
> UHD_003.007.002-94-ge56809a0
>
> UHD RX samples to file Allowed options:
>   --help                         help message
>   --args arg                     multi uhd device address args
>   --file arg (=usrp_samples.dat) name of the file to write binary samples
> to
>   --type arg (=short)            sample type: double, float, or short
>   --nsamps arg (=0)              total number of samples to receive
>   --time arg (=0)                total number of seconds to receive
>   --spb arg (=10000)             samples per buffer
>   --rate arg (=1000000)          rate of incoming samples
>   --freq arg (=0)                RF center frequency in Hz
>   --gain arg                     gain for the RF chain
>   --ant arg                      daughterboard antenna selection
>   --subdev arg                   daughterboard subdevice specification
>   --bw arg                       daughterboard IF filter bandwidth in Hz
>   --ref arg (=internal)          reference source (internal, external,
> mimo)
>   --wirefmt arg (=sc16)          wire format (sc8 or sc16)
>   --setup arg (=1)               seconds of setup time
>   --progress                     periodically display short-term bandwidth
>   --stats                        show average bandwidth on exit
>   --sizemap                      track packet size and display breakdown
> on
>                                  exit
>   --null                         run without writing to file
>   --continue                     don't abort on a bad packet
>   --skip-lo                      skip checking LO lock status
>   --int-n                        tune USRP with integer-N tuning
>
> And, uhd_rx_cfile  (A Gnu Radio app):
>
> linux; GNU C++ version 4.7.2 20121109 (Red Hat 4.7.2-8); Boost_105000;
> UHD_003.007.002-94-ge56809a0
>
> Usage: uhd_rx_cfile: [options] output_filename
>
> Options:
>   -h, --help            show this help message and exit
>   -a ARGS, --args=ARGS  UHD device address args , [default=]
>   --spec=SPEC           Subdevice of UHD device where appropriate
>   -A ANTENNA, --antenna=ANTENNA
>                         select Rx Antenna where appropriate
>   --samp-rate=SAMP_RATE
>                         set sample rate (bandwidth) [default=1000000.0]
>   -f FREQ, --freq=FREQ  set frequency to FREQ
>   -g GAIN, --gain=GAIN  set gain in dB (default is midpoint)
>   -s, --output-shorts   output interleaved shorts instead of complex floats
>   -N NSAMPLES, --nsamples=NSAMPLES
>                         number of samples to collect [default=+inf]
>   -v, --verbose         verbose output
>   --lo-offset=LO_OFFSET
>                         set daughterboard LO offset to OFFSET [default=hw
>                         default]
>   --wire-format=WIRE_FORMAT
>                         set wire format from USRP [default=sc16
>   --stream-args=STREAM_ARGS
>                         set stream arguments [default=]
>   --show-async-msg      Show asynchronous message notifications from UHD
>                         [default=False]
> linux; GNU C++ version 4.7.2 20121109 (Red Hat 4.7.2-8); Boost_105000;
> UHD_003.007.002-94-ge56809a0
>
> Usage: uhd_rx_cfile: [options] output_filename
>
> Options:
>   -h, --help            show this help message and exit
>   -a ARGS, --args=ARGS  UHD device address args , [default=]
>   --spec=SPEC           Subdevice of UHD device where appropriate
>   -A ANTENNA, --antenna=ANTENNA
>                         select Rx Antenna where appropriate
>   --samp-rate=SAMP_RATE
>                         set sample rate (bandwidth) [default=1000000.0]
>   -f FREQ, --freq=FREQ  set frequency to FREQ
>   -g GAIN, --gain=GAIN  set gain in dB (default is midpoint)
>   -s, --output-shorts   output interleaved shorts instead of complex floats
>   -N NSAMPLES, --nsamples=NSAMPLES
>                         number of samples to collect [default=+inf]
>   -v, --verbose         verbose output
>   --lo-offset=LO_OFFSET
>                         set daughterboard LO offset to OFFSET [default=hw
>                         default]
>   --wire-format=WIRE_FORMAT
>                         set wire format from USRP [default=sc16
>   --stream-args=STREAM_ARGS
>                         set stream arguments [default=]
>   --show-async-msg      Show asynchronous message notifications from UHD
>                         [default=False]
>
>
> You should try them both--they both support recording data as "shorts".
> Which is certainly space efficient.  There is no packed-12-bit recording
> format.
>
>
>
>
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>
>
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