Questions about benchmark_tx/benchmark_rx

GNU Radio
1

I used the benchmark_tx and benchmark_rx to transmit data and I have
some
questions:

  1. I set the frequency of both benchmark_tx and benchmark_rx to 300M,
    the
    transmission succeed; but it failed when I set the frequency to 2.4G or
    other frequencies. Why is this?
  2. Both the benchmark_tx and benchmark_rx gives the warning as I marked
    red: the actual frequency is not same but the transmission succeed. Why
    is
    it?
  3. In the receiving end, the pktno is disordered some pktnos are much
    larger than averages. Why is it?
  4. What does the n_right=0 means? Does it mean the packet is corrupted
    in
    the receiving end?

The benchmark_tx messages as following:
belltestbed@belltestbed-OptiPlex-790
:~/Desktop/gnuradio/gr-digital/les/narrowband$ ./benchmark_tx.py -f 300M
–from-file=pic.jpg
linux; GNU C++ version 4.6.3; Boost_104601;
UHD_003.004.002-128-g12f7a5c9

gr_fir_ccf: using SSE
– Opening a USRP2/N-Series device…
– Current recv frame size: 1472 bytes
– Current send frame size: 1472 bytes

UHD Warning:
The recv buffer could not be resized sufficiently.
Target sock buff size: 50000000 bytes.
Actual sock buff size: 1000000 bytes.
See the transport application notes on buffer resizing.
Please run: sudo sysctl -w net.core.rmem_max=50000000

UHD Warning:
The recv buffer could not be resized sufficiently.
Target sock buff size: 50000000 bytes.
Actual sock buff size: 1000000 bytes.
See the transport application notes on buffer resizing.
Please run: sudo sysctl -w net.core.rmem_max=50000000

UHD Warning:
The send buffer could not be resized sufficiently.
Target sock buff size: 1048576 bytes.
Actual sock buff size: 1000000 bytes.
See the transport application notes on buffer resizing.
Please run: sudo sysctl -w net.core.wmem_max=1048576

UHD Warning:
Unable to set the thread priority. Performance may be negatively
affected.
Please see the general application notes in the manual for
instructions.
EnvironmentError: OSError: error in pthread_setschedparam

No gain specified.
Setting gain to 17.500000 (from [0.000000, 35.000000])

UHD Warning:
The hardware does not support the requested TX frequency:
Target frequency: 300.000000 MHz
Actual frequency: 4500.000000 MHz

UHD Warning:
The hardware does not support the requested TX sample rate:
Target sample rate: 0.050000 MSps
Actual sample rate: 0.195312 MSps

Symbol Rate: 25000.000000
Requested sps: 2.000000
Given sample rate: 195312.500000
Actual sps for rate: 7.812500

Requested sample rate: 50000.000000
Actual sample rate: 195312.500000
Using Volk machine: avx_32
Warning: failed to enable realtime scheduling
…

And the benchmark_rx messages as follwing:
bell@bell-HP-Compaq-4000-Pro-SFF-PC
:~/Desktop/USRP/gnuradio/gr-digital/examples/narrowband$
./benchmark_rx.py
-f 300M
linux; GNU C++ version 4.6.3; Boost_104601;
UHD_003.004.001-129-g23344268

gr_fir_ccf: using SSE
– Opening a USRP2/N-Series device…
– Current recv frame size: 1472 bytes
– Current send frame size: 1472 bytes

UHD Warning:
The recv buffer could not be resized sufficiently.
Target sock buff size: 50000000 bytes.
Actual sock buff size: 1000000 bytes.
See the transport application notes on buffer resizing.
Please run: sudo sysctl -w net.core.rmem_max=50000000

UHD Warning:
The recv buffer could not be resized sufficiently.
Target sock buff size: 50000000 bytes.
Actual sock buff size: 1000000 bytes.
See the transport application notes on buffer resizing.
Please run: sudo sysctl -w net.core.rmem_max=50000000

UHD Warning:
The send buffer could not be resized sufficiently.
Target sock buff size: 1048576 bytes.
Actual sock buff size: 1000000 bytes.
See the transport application notes on buffer resizing.
Please run: sudo sysctl -w net.core.wmem_max=1048576

UHD Warning:
Unable to set the thread priority. Performance may be negatively
affected.
Please see the general application notes in the manual for
instructions.
EnvironmentError: OSError: error in pthread_setschedparam

No gain specified.
Setting gain to 49.500000 (from [0.000000, 99.000000])

UHD Warning:
The hardware does not support the requested RX frequency:
Target frequency: 300.000000 MHz
Actual frequency: 2400.000000 MHz

UHD Warning:
The hardware does not support the requested RX sample rate:
Target sample rate: 0.050000 MSps
Actual sample rate: 0.195312 MSps

Symbol Rate: 25000.000000
Requested sps: 2.000000
Given sample rate: 195312.500000
Actual sps for rate: 7.812500

Requested sample rate: 50000.000000
Actual sample rate: 195312.500000
Warning: Failed to enable realtime scheduling.
Using Volk machine: ssse3_32
ok = False pktno = 3850 n_rcvd = 1 n_right = 0
ok = False pktno = 53042 n_rcvd = 2 n_right = 0
ok = False pktno = 61454 n_rcvd = 3 n_right = 0
ok = False pktno = 27 n_rcvd = 4 n_right = 0
ok = False pktno = 41 n_rcvd = 5 n_right = 0
ok = False pktno = 44 n_rcvd = 6 n_right = 0
ok = False pktno = 44 n_rcvd = 7 n_right = 0
ok = False pktno = 51 n_rcvd = 8 n_right = 0
ok = False pktno = 43 n_rcvd = 9 n_right = 0
ok = False pktno = 64 n_rcvd = 10 n_right = 0

I am using two USRP N210.

2

UHD Warning:
The hardware does not support the requested TX frequency:
Target frequency: 300.000000 MHz
Actual frequency: 4500.000000 MHz

UHD Warning:
The hardware does not support the requested TX sample rate:
Target sample rate: 0.050000 MSps
Actual sample rate: 0.195312 MSps

  1. Be careful to pick frequencies and sample rates that the hardware is
    capable of handling. That will help you immensely.

Here is a list of freq ranges for each particular daughter-board:
http://files.ettus.com/uhd_docs/manual/html/dboards.html

  1. I recommend debugging at a lower level to ensure the fidelity of your
    setup, like a test tone, and so on.

-josh

3

On Fri, Jun 1, 2012 at 1:01 PM, Weixian Z. [email protected] wrote:

I used the benchmark_tx and benchmark_rx to transmit data and I have some
questions:

  1. I set the frequency of both benchmark_tx and benchmark_rx to 300M, the
    transmission succeed; but it failed when I set the frequency to 2.4G or
    other frequencies. Why is this?

What daughter board u are using, maybe your daughter board doesn’t
support
2.4GHz,
Target frequency: 300.000000 MHz
Actual frequency: 4500.000000 MHz
means u daughter board runs on 4.5GHz

  1. Both the benchmark_tx and benchmark_rx gives the warning as I marked
    red: the actual frequency is not same but the transmission succeed. Why is
    it?

Target frequency: 300.000000 MHz
Actual frequency: 4500.000000 MHz
means u daughter board runs on 4.5GHz, maybe it doesn’t support 300MHz

  1. In the receiving end, the pktno is disordered some pktnos are much
    larger than averages. Why is it?

They are disrupted, so maybe some random numbers

  1. What does the n_right=0 means? Does it mean the packet is corrupted
    in

the receiving end?

n_right means how many packets are correctly received, which means their
crc check should be true (ok=True)