Bitrate doubt

GNU Radio
1

hi folks,
I am using BENCHMARK_TX.PY, BENCHMARK_RX.PY to test the
transmission and reception of signals. I have doubts regarding the outpu
that is appearing on the screen.

gr_fir_fff: using SSE
socket(PF_PACKET, SOCK_RAW, htons(0xBEEF)): Operation not permitted
eth0: socket: No such file or directory
Requested RX Bitrate: 100k
Actual Bitrate: 125k
Warning: Failed to enable realtime scheduling.

  1. What is the SOCKET part in the output
  2. What is the difference between Actual Bitrate and Requested Bitrate
    3)How to enable real time scheduling
    4)I am always loosing the last 5-10 packets during the reception. What
    is
    the reason behind this loss. ( I tried varying packet size , bitrate
    also.
    But no use)

Thanks,
Amarnath

2

amarnath alapati wrote:

Warning: Failed to enable realtime scheduling.

  1. What is the SOCKET part in the output
    Running as root should resolve this. But this should also be resolved by
    means described on the wiki- page.
  2. What is the difference between Actual Bitrate and Requested Bitrate
    The actual bit rate is calculated from a couple of parameters, and I
    think actual bit- rate is “close enough” to the requested one, given
    that there are some limitations regarding decimation/interpolation rates
    and so forth…
    3)How to enable real time scheduling
    There are some ways to elivate the privs. The quickest way is to run the
    aplication as root. This is not the recomended way, which has something
    to do with setting some privlegies and execution bits for an
    application. More information should be avaliable in the archives, and
    on the wiki- page.
3

Run:

sudo chmod u+s /usr/local/bin/usrp2_socket_opener

  1. As root edit /etc/security/limits.conf and add the line:

@usrp - rtprio 50

If your not already in the USRP group add your user with:

useradd -G usrp username

(This will create the group if it doesn’t already exist)

–

Tim

4

Mattias K. wrote:

Actual Bitrate: 125k
Warning: Failed to enable realtime scheduling.

  1. What is the difference between Actual Bitrate and Requested Bitrate
    The actual bit rate is calculated from a couple of parameters, and I
    think actual bit- rate is “close enough” to the requested one, given
    that there are some limitations regarding decimation/interpolation
    rates and so forth…

Yes, right now the code is designed to only allow an integer number of
samples per symbol and then find the decimation/interpolation rate that
gets as close to the requested bit rate as it can. We should update the
code to use the pfb_resampler to allow any requested bitrate.

Tom