Command Line Arguments for usrp transmission and reception

GNU Radio
1

Hi,
I posted my question a couple of days ago but could not get any
response, probably because it was an over-datailed mail. Here, I am just
posting a part of it,

Is there any problem if I do call benchmark_rx.py and benchmark_tx.py
with following command line arguments?
$ python ./benchmark_rx.py -f 10M -R A --rx-gain=70 -v -r 500K
$ python ./benchmark_tx.py -TA -f 10M -r 500k -v --tx-amplitude=20000

While doing so, I am getting following outputs:

I called benchmark_rx on my usrp and left it running,

$ python ./benchmark_rx.py -f 10M -R A --rx-gain=70 -v -r 500K

bits per symbol = 1
M&M clock recovery omega = 2.000000
M&M clock recovery gain mu = 0.175000
M&M clock recovery mu = 0.500000
M&M clock recovery omega rel. limit = 0.005000
frequency error = 0.000000

Receive Path:
Using RX d’board A: Basic Rx
Rx gain:Â Â Â Â Â Â Â Â 70
modulation:Â Â Â Â Â gmsk_demod
bitrate:Â Â Â Â Â Â Â Â 250kb/s
samples/symbol:Â Â Â 2
decim:Â Â Â Â Â Â Â Â Â Â 128
Rx Frequency:Â Â Â 10M

I then called benchmark_tx on my second usrp,

$ python ./benchmark_tx.py -TA -f 10M -r 500k -v --tx-amplitude=20000

gr_fir_fff: using SSE
bits per symbol = 1
Gaussian filter bt = 0.35
Using TX d’board A: Basic Tx
Tx amplitude    20000.0
modulation:Â Â Â Â Â gmsk_mod
bitrate:Â Â Â Â Â Â Â Â 500kb/s
samples/symbol:Â Â Â 2
interp:Â Â Â Â Â Â Â Â Â 128
Tx Frequency:Â Â Â 10M

This shows packets are apparently being transmitted. However when I
checked the console of second machine for benchmark_rx, no packet
notifications are being displayed.

My Questions:
1- Is the USRP transmitting data?
2- Why is it not receiving this data if it is transmitting?

-Ahmed

2

2009/3/23 Ahmed Majeed K. [email protected]:

$ python ./benchmark_rx.py -f 10M -R A --rx-gain=70 -v -r 500K
bitrate: 250kb/s

$ python ./benchmark_tx.py -TA -f 10M -r 500k -v --tx-amplitude=20000
bitrate: 500kb/s

The transmitter and receiver are operating at different rates. Try
changing your transmitter to -r250k to match the receiver.

Johnathan

3

Quoting “Johnathan C.” [email protected]:

$ python ./benchmark_rx.py -f 10M -R A --rx-gain=70 -v -r 500K
bitrate:Â Â Â Â Â Â Â Â 250kb/s

$ python ./benchmark_tx.py -TA -f 10M -r 500k -v --tx-amplitude=20000
bitrate:Â Â Â Â Â Â Â Â 500kb/s

Bitrate while using above command line arguments is 500kb/s at both,
transmitter and receiver.

The transmitter and receiver are operating at different rates. Try
changing your transmitter to -r250k to match the receiver.

Changing transmitter to -r 250k makes transmitter rate 250kb/s,
apparently creates a mismatch between transmitter and receiver. However,
in either case, receiver console displays nothing for any packet
reception. The outputs include:

$ python ./benchmark_rx.py -f 10M -R A --rx-gain=70 -v -r 500K

gr_fir_fff: using SSE
bits per symbol = 1
M&M clock recovery omega = 2.000000
M&M clock recovery gain mu = 0.175000
M&M clock recovery mu = 0.500000
M&M clock recovery omega rel. limit = 0.005000
frequency error = 0.000000

Receive Path:
Using RX d’board A: Basic Rx
Rx gain:Â Â Â Â Â Â Â Â 70
modulation:Â Â Â Â Â gmsk_demod
bitrate:Â Â Â Â Â Â Â Â 500kb/s
samples/symbol:Â Â Â 2
decim:Â Â Â Â Â Â Â Â Â Â 64
Rx Frequency:Â Â Â 10M

$ python ./benchmark_tx.py -TA -f 10M -r 500k -v --tx-amplitude=20000

gr_fir_fff: using SSE
bits per symbol = 1
Gaussian filter bt = 0.35
Using TX d’board A: Basic Tx
Tx amplitude    20000.0
modulation:Â Â Â Â Â gmsk_mod
bitrate:Â Â Â Â Â Â Â Â 500kb/s
samples/symbol:Â Â Â 2
interp:Â Â Â Â Â Â Â Â Â 128
Tx Frequency:Â Â Â 10M

$ python ./benchmark_tx.py -TA -f 10M -r 250k -v --tx-amplitude=20000

gr_fir_fff: using SSE
bits per symbol = 1
Gaussian filter bt = 0.35
Using TX d’board A: Basic Tx
Tx amplitude    20000.0
modulation:Â Â Â Â Â gmsk_mod
bitrate:Â Â Â Â Â Â Â Â 250kb/s
samples/symbol:Â Â Â 2
interp:Â Â Â Â Â Â Â Â Â 256
Tx Frequency:Â Â Â 10M

-Ahmed

4

On Tue, 2009-03-24 at 13:34 -0400, Ahmed Majeed K. wrote:

$ python ./benchmark_rx.py -f 10M -R A --rx-gain=70 -v -r 500K
bitrate: 250kb/s

$ python ./benchmark_tx.py -TA -f 10M -r 500k -v
–tx-amplitude=20000

bitrate: 500kb/s

Bitrate while using above command line arguments is 500kb/s at both,
transmitter and receiver.

Um, the lines quoted above are from your own output, clearly showing
they are different. Also, the correct form for specifying the bitrate
is to use lower case ‘k’; the above will actually give you an error.

Changing transmitter to -r 250k makes transmitter rate 250kb/s,
apparently creates a mismatch between transmitter and receiver.

What are you talking about?

However, in either case, receiver console displays nothing for any
packet reception.

You are using two different USRPs, and they are connected by some sort
of cable, correct?

Johnathan