Hi,
I completed the installations and checked tone generation and benchmark_tx/rx
over a pair of usrp, along with usrp_wfm_rcv.py for or FM reception. These
examles ran pretty fine. Then I tried tunnel.py with command line arguments as
in README file:
./tunnel.py -f 423.0M --bitrate=500k
The output was a series of 'B', stating no carrier sensing.
I reduced the carrier freauency to 10 M and tried running it again. This time,
there was no 'B' sequence and the output of first machine was:
>>>gr_fir_fff
modulation: gmsk
frequency: 10M
bitrate: 500kb/sec
sample/symbol: 2
Carrier Sense Threshold: 30dB
Allocated Virtual Network Interface: gr0
Then, after ifconfig on another terminal window, first window showed:
Tx: len(payload) = 90
Tx: len(payload) = 54
Rx: ok = false len(payload) = 90
Tx: len(payload) = 289
Tx: len(payload) = 193
Tx: len(payload) = 289
Tx: len(payload) = 78
Tx: len(payload) = 289
Tx: len(payload) = 265
Rx: ok = false len(payload) = 265
and so on..........
The output of the second machine was identical, except there was NO "Rx: ok =
true/false len(payload) = xx" in that.
When I pinged one machine with other, the following error message appeared:
PING 192.168.200.1 (192.168.200.1) 56(84) bytes of data
>From 192.168.200.2 icmp_seq=1 Destination Host Unreachable
(Till icmp_seq=32, when I disconnected).
After that, I am able to run usrp_wfm_rcv.py, but when I again ran
benchmark_rx.py and benchmark_tx.py, following is the output with NO packet
reception:
(Please note, earlier I used same command line arguments and got some packets
received)
I call benchmark_rx on my usrp and leave 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: 70
modulation: gmsk_demod
bitrate: 250kb/s
samples/symbol: 2
decim: 128
Rx Frequency: 10M
I then call 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: gmsk_mod
bitrate: 500kb/s
samples/symbol: 2
interp: 128
Tx Frequency: 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?
3- Do 'Carrier Sensing' has something to do with frequency, in tunnel.py?
-Ahmed
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