Help required tunnel.py

GNU Radio
1

Hi,After playing with the parameters I finally got some communication
possible. I must say that the code is highly unriable. However when I do
“sudo ifconfig gr0 192.168.200.1” i get “BBBBBBBBBBBBBBBB”. I think
that it means that the usrp is not getting free carriers to transmit on.
If so what is the solution. If i am wrong please correct me.,Thank you.

2

On Tue, Jul 06, 2010 at 03:32:45PM +0000, chuck lorres wrote:

Hi,After playing with the parameters I finally got some
communication possible. I must say that the code is highly
unriable. However when I do “sudo ifconfig gr0 192.168.200.1” i get
“BBBBBBBBBBBBBBBB”. I think that it means that the usrp is not
getting free carriers to transmit on. If so what is the solution. If
i am wrong please correct me.,Thank you.

Try adjusting the carrier threshold using the command line option.

Eric

3

That’s pretty much the same settings that I have. Can you clarify a bit
more:

  • How far apart are your boards?

  • What options did you use to run tunnel, benchmark_ofdm_, benchmark_.

  • When you run benchmark_*, did you get a lot of packet drops at the end
    of
    transmission (about 15%)?

Thanks a lot,

Tuan

4

I finally found a setting that actually works. So the real problem I
think
lies in the bit rate. I had no communication whatsoever in low bit rate
(~250k). I started to have unreliable comm. at 500k and at 1Mbps I got
no
packet drops for tunnel.py. However, even at 1Mbps I still got about 5%
drops using benchmark_* (always at the end).

My theory is that lower bit rate corresponds to lower signal bandwidth.
I
think in some mixer/filter stage the frequency offset is too large thus
push
all of my useful bandwidth out of the passing band. With higher
bandwidth, a
large path of the useful bandwidth remains in spite of the frequency
offset,
thus the receiver was able to pick up some thing. Lower bandwidth works
fine
for Chuck so he might not have the frequency offset problem.

Let me know if anyone has a better explanation.

Tuan

5

Thanks for your reply.Well I am trying to run the tunnel.py in ofdm
folder. However there is no bit rate option in it.If you have been able
to successfully run it, please send me the parameters that you changed?I
have tried all day to run it but to no avail.Not even a single packet is
being sensed.In digital folders tunnel.py is running perfectly.Thanks.

Date: Thu, 8 Jul 2010 13:07:04 -0400
Subject: Re: [Discuss-gnuradio] Re: Help required tunnel.py
From: [email protected]
To: [email protected]; [email protected]

I finally found a setting that actually works. So the real problem I
think lies in the bit rate. I had no communication whatsoever in low bit
rate (~250k). I started to have unreliable comm. at 500k and at 1Mbps I
got no packet drops for tunnel.py. However, even at 1Mbps I still got
about 5% drops using benchmark_* (always at the end).

My theory is that lower bit rate corresponds to lower signal bandwidth.
I think in some mixer/filter stage the frequency offset is too large
thus push all of my useful bandwidth out of the passing band. With
higher bandwidth, a large path of the useful bandwidth remains in spite
of the frequency offset, thus the receiver was able to pick up some
thing. Lower bandwidth works fine for Chuck so he might not have the
frequency offset problem.

Let me know if anyone has a better explanation.

Tuan

On Thu, Jul 8, 2010 at 11:12 AM, chuck lorres [email protected]
wrote:

-How far apart are your boards?
1meter apart

  • What options did you use to run tunnel, benchmark_ofdm_, benchmark_.
    default with 2.41G frequency.
  • When you run benchmark_*, did you get a lot of packet drops at the end
    of transmission (about 15%)?

perfect reception was observed. 0 packets were dropped.

Date: Thu, 8 Jul 2010 11:09:30 -0400
Subject: Re: [Discuss-gnuradio] Re: Help required tunnel.py
From: [email protected]

To: [email protected]; [email protected]

That’s pretty much the same settings that I have. Can you clarify a bit
more:

  • How far apart are your boards?

  • What options did you use to run tunnel, benchmark_ofdm_, benchmark_.

  • When you run benchmark_*, did you get a lot of packet drops at the end
    of transmission (about 15%)?

Thanks a lot,

Tuan

On Thu, Jul 8, 2010 at 10:55 AM, chuck lorres [email protected]
wrote:

I am using RFX 2400, gnuradio 3.2.2, ubuntu 9.10 and 9.04 on another

Date: Thu, 8 Jul 2010 10:48:24 -0400
Subject: Re: [Discuss-gnuradio] Re: Help required tunnel.py
From: [email protected]

To: [email protected]
CC: [email protected]

Chuck,

What hardware are you using?

On Thu, Jul 8, 2010 at 10:38 AM, chuck lorres [email protected]
wrote:

Hi,
I have successfully run digital folders tunnel.py.
However, I am not receiving anything when i run the ofdm folder
tunnel.py.
Whereas the benchmark_ofdm_tx+rx.py is running perfectly.
I have varied almost all the available parameters but to no avail.

Please help me out.
Thanks in advance.
Chuck.

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6

Unfortunately tunnel.py in the ofdm folder doesn’t work for me either.
Since
you had benchmark_ofdm_* running, I would use the same settings for
tunnel.
I don’t even have benchmark_ofdm_* going at any setting. I’m trying to
get a
hold of a spectrum analyzer. Hopefully it would help to clear things up.

A quick question: what bit rate did you use for your benchmark_tx/rx?
The
default bit rate is 100kbps, which would get bumped up to 125kbps.

Tuan