Dvb-t project with two USRPN200 devices failure

Hi all,

I am using ubuntu 13.04, GNURADIO 3.7.
I cannot transmit or receive using two (USRPN200 + XCRV2450
d.board+VERT2450 antennas) devices for DVB-T project.
Here is the dvb-t project: https://github.com/BogdanDIA/gr-dvbt

It will be very helpful and appreciated if you help me. If someone
tested it or can do it, please let me know. As far as I know someone
tested it with N210 model.

I think this failure is due to high noise/interference or smt. else.
However I tested it already with all possible configurations. I also
attach my .grc files.

Hi, not having access to my setup for now but for the beginning you
could try recording the spectrum with your USRP and then use the file
source to decode the signal offline. There is a script file
apps/capture.sh that I usually use to capture data. You may tweak it for
your needs (frequency, gain).

Sometimes it was reported that on old cpus the processing power is not
enough so that the result is an overflow (you directly see a long OOO
message in this case). Try to see if this is the case.

One way to reduce the overhead is to run the receiving flow directly
from command line instead of gnuradio-companion (e.g. ./top_block >
out.txt) after you have generated the flowgraph. The gnuradio-companion
cannot cope with big amount of data when the blocks gets out a lot of
text.

Bogdan

On Monday, March 31, 2014 1:22 PM, Nasi [email protected] wrote:

Hi all,

I am using ubuntu 13.04, GNURADIO 3.7.
I cannot transmit or receive using two (USRPN200 + XCRV2450
d.board+VERT2450 antennas) devices for DVB-T project.
Here is the dvb-t project:https://github.com/BogdanDIA/gr-dvbt

It will be very helpful and appreciated if you help me. If someone
tested it or can do it, please let me know. As far as I know someone
tested it with N210 model.

I think this failure is due to high noise/interference or smt. else.
However I tested it already with all possible configurations. I also
attach my .grc files.

Hi,

Thanks!

I am using collected data also as you say.
I am using sampling rate of 1 Mbps instead of 10 Mbps which must be the
same for static transmission. Isn’t it?

Mon, 31 Mar 2014 08:23:01 -0700 (PDT) от Bogdan D.
[email protected]:

Hi, not having access to my setup for now but for the beginning you could try
recording the spectrum with your USRP and then use the file source to decode the
signal offline. There is a script file apps/capture.sh that I usually use to
capture data. You may tweak it for your needs (frequency, gain).

Sometimes it was reported that on old cpus the processing power is not enough so
that the result is an overflow (you directly see a long OOO message in this case).
Try to see if this is the case.

One way to reduce the overhead is to run the receiving flow directly from command
line instead of gnuradio-companion (e.g. ./top_block > out.txt) after you have
generated the flowgraph. The gnuradio-companion cannot cope with big amount of
data when the blocks gets out a lot of
text.

ohhh, now I understand.
It produces UUUU in the transmitter side - which probably means
underflow with my laptop.
Do you know how to decrease this power?

Mon, 31 Mar 2014 08:44:49 -0700 (PDT) от Bogdan D.
[email protected]:

I am using collected data also as
you say.
One way to reduce the overhead is to run the receiving flow directly from command
line instead of gnuradio-companion (e.g. ./top_block > out.txt) after
you have generated the flowgraph. The gnuradio-companion cannot cope
with big amount of data when the blocks gets out a lot of
text.

For dvbt the bandwidth is around 9.14Msps so with the rational resampler
you need to set-up the USRP at 10Msps. 1Msps will not work as only a
part of the spectrum will be received.

Bogdan

On Monday, March 31, 2014 6:36 PM, Nasi [email protected] wrote:

Hi,

Thanks!

I am using collected data also as you say.
I am using sampling rate of 1 Mbps instead of 10 Mbps which must be the
same for static transmission. Isn’t it?

Mon, 31 Mar 2014 08:23:01 -0700 (PDT) от Bogdan D.
[email protected]:

Hi, not having access to my setup for now but for the beginning you
could try recording the spectrum with your USRP and then use the file
source to decode the signal offline. There is a script file
apps/capture.sh that I usually use to capture data. You may tweak it for
your needs (frequency, gain).

Sometimes it was reported that on old cpus the processing power is not
enough so that the result is an overflow (you directly see a long OOO
message in this case). Try to see if this is the case.

One way to reduce the overhead is to run the receiving flow directly
from command line instead of gnuradio-companion (e.g. ./top_block >
out.txt) after you have generated the flowgraph. The gnuradio-companion
cannot cope with big amount of data when the blocks gets out a lot of
text.

Bogdan

On Monday, March 31, 2014 1:22 PM, Nasi [email protected] wrote:

Hi all,

I am using ubuntu 13.04, GNURADIO 3.7.
I cannot transmit or receive using two (USRPN200 + XCRV2450
d.board+VERT2450 antennas) devices for DVB-T project.
Here is the dvb-t project: https://github.com/BogdanDIA/gr-dvbt

It will be very helpful and appreciated if you help me. If someone
tested it or can do it, please let me know. As far as I know someone
tested it with N210 model.

I think this failure is due to high noise/interference or smt. else.
However I tested it already with all possible configurations. I also
attach my .grc files.


NE

One thing I did once and worked are:

  1. Use a file sink instead of USRP when transmitting. Then, once the
    file is generated send the samples from file (opened in a file source)
    directly to USRP. That will need a good harddrive with at least 80MB/s
    read speed, a SSD will work probably.

  2. Do the above but write the file int RAM like dd if=yourfile.bin
    of=/dev/ram0 - you may need to give root access. Then open /dev/ram0 in
    a file source and send it to USRP. This will consume you RAM and will
    potentiall lock your laptop if the .bin file is bigger than RAM size.

But, indeed you probably need a better computer.

Bogdan

On Monday, March 31, 2014 6:59 PM, Marcus M. [email protected]
wrote:

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

I’m afraid you can’t reduce needed sample rate for a fixed bandwidth.

You need a stronger laptop. Often, plugging it into mains power helps.

Marcus

On 31.03.2014 17:52, Nasi wrote:

work as only a part of the spectrum will be received.
you say.
offline. There is a script file apps/capture.sh that I usually
line instead of gnuradio-companion (e.g. ./top_block > out.txt)
I am using ubuntu 13.04, GNURADIO 3.7. I cannot transmit or
configurations. I also attach my .grc files.

_______________________________________________ Discuss-gnuradio
mailing list [email protected]
https://lists.gnu.org/mailman/listinfo/discuss-gnuradio

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Thanks a lot! I will try them too…

Mon, 31 Mar 2014 09:08:04 -0700 (PDT) от Bogdan D.
[email protected]:

Marcus

For dvbt the bandwidth is around 9.14Msps so with the rational

now but for the beginning you could try recording the spectrum
with your USRP and then use the file source to decode the signal
offline. There is a script file apps/capture.sh that I usually
use to capture data. You may tweak it for your
needs (frequency,

after you have generated the flowgraph. The gnuradio-companion
cannot cope with big amount of data when the blocks gets out a lot
of text.

Bogdan

On Monday,
March 31, 2014 1:22 PM, Nasi < [email protected] >

I think this failure is due to high
noise/interference or smt.

– NE

_______________________________________________ Discuss-gnuradio

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

I’m afraid you can’t reduce needed sample rate for a fixed bandwidth.

You need a stronger laptop. Often, plugging it into mains power helps.

Marcus

On 31.03.2014 17:52, Nasi wrote:

work as only a part of the spectrum will be received.
you say.
offline. There is a script file apps/capture.sh that I usually
line instead of gnuradio-companion (e.g. ./top_block > out.txt)
I am using ubuntu 13.04, GNURADIO 3.7. I cannot transmit or
configurations. I also attach my .grc files.

_______________________________________________ Discuss-gnuradio
mailing list [email protected]
https://lists.gnu.org/mailman/listinfo/discuss-gnuradio

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Yes, it’s possible. The use of the rational re-sampler
is to be compatible with commercial DVB-T receivers.
If you’re just interested in USRP to USRP, then it’s
okay to use a 10 Msps sample rate. The signal will
be slightly wider than a standard 8 MHz signal at
9.142857 Msps.

You can modify my DVB-T Transport Stream bitrate
calculator to determine the required bitrates at 10 Msps.

https://github.com/drmpeg/dtv-utils/blob/master/dvbtrate.c

Ron

Can I trans/receive without Rational Resampler?
It distorts the signal too much :frowning:

Mon, 31 Mar 2014 20:12:27 +0400 от Nasi [email protected]:

I’m afraid you can’t reduce needed sample rate for a fixed bandwidth.

On Monday, March 31, 2014 6:36 PM, Nasi < [email protected] >

Mon, 31 Mar 2014 08:23:01 -0700 (PDT) ?? Bogdan D.
< [email protected] >: Hi, not having access to my setup for
now but for the beginning you could try recording the spectrum
with your USRP and then use the file source to decode the signal
offline. There is a script file apps/capture.sh that I usually
use to capture data. You may tweak it for your
needs (frequency,

after you have generated the flowgraph. The gnuradio-companion
cannot cope with big amount of data when the blocks gets out a lot
of text.

Bogdan

On Monday,
March 31, 2014 1:22 PM, Nasi < [email protected] >

I think this failure is due to high
noise/interference or smt.

– NE

_______________________________________________ Discuss-gnuradio

Not actually, not possible. I tested today. It does not receive
anything.

Thu, 17 Apr 2014 15:53:39 -0700 от Ron E. [email protected]:

https://github.com/drmpeg/dtv-utils/blob/master/dvbtrate.c

Thanks a lot! I will try them too…

Mon, 31 Mar 2014 09:08:04 -0700 (PDT) от Bogdan
Diaconescu [email protected] :

One thing I did once and worked are:

  1. Use a file sink instead of USRP when
    transmitting. Then, once the file is
    generated send the samples from file (opened
    in a file source) directly to USRP. That
    will need a good harddrive with at least
    80MB/s read speed, a SSD will work probably.
  1. Do the above but write the file int RAM
    like dd if=yourfile.bin of=/dev/ram0 - you
    may need to give root access. Then open
    /dev/ram0 in a file source and send it to
    USRP. This will consume you RAM and will
    potentiall lock your laptop if the .bin file
    is bigger than RAM size.

But, indeed you probably need a better
computer.

Bogdan

On Monday, March 31,
2014 6:59 PM, Marcus Müller
[email protected] wrote:

-----BEGIN PGP SIGNED
MESSAGE-----

Hash: SHA1

I’m afraid you can’t reduce needed
sample rate for a fixed bandwidth.

You need a stronger laptop. Often,
plugging it into mains power helps.

Marcus

On 31.03.2014 17:52, Nasi wrote:

ohhh, now I understand. It
produces UUUU in the transmitter
side -

which probably means underflow
with my laptop. Do you know how to

decrease this power?

Mon, 31 Mar 2014 08:44:49 -0700
(PDT) ?? Bogdan D.

< [email protected] >:

For dvbt the bandwidth is
around 9.14Msps so with the rational

resampler you need to
set-up the USRP at 10Msps. 1Msps
will not

work as only a part of the
spectrum will be received.

Bogdan

On Monday, March 31, 2014
6:36 PM, Nasi < [email protected] >

wrote: Hi,

Thanks!

I am using collected data
also as

you say.

I am using sampling rate of
1 Mbps instead of 10 Mbps which must

be the same for static
transmission. Isn’t it?

Mon, 31 Mar 2014 08:23:01
-0700 (PDT) ?? Bogdan D.

< [email protected] >:
Hi, not having access to my setup
for

now but for the beginning
you could try recording the spectrum

with your USRP and then use
the file source to decode the signal

offline. There is a script
file apps/capture.sh that I usually

use to capture data. You
may tweak it for your needs
(frequency,

gain).

Sometimes it was reported
that on old cpus the processing
power

is not enough so that the
result is an overflow (you directly
see

a long OOO message in this
case). Try to see if this is the

case.

One way to reduce the
overhead is to run the receiving
flow

directly from command
line instead of
gnuradio-companion (e.g. ./top_block
out.txt)

after you have generated the
flowgraph. The gnuradio-companion

cannot cope with big amount of
data when the blocks gets out a lot

of text.

Bogdan

On Monday, March 31, 2014
1:22 PM, Nasi < [email protected] >

wrote: Hi all,

I am using ubuntu 13.04,
GNURADIO 3.7. I cannot transmit or

receive using two (USRPN200

                                + XCRV2450 d.board+VERT2450
                                antennas)

devices for DVB-T project.
Here is the dvb-t project:

https://github.com/BogdanDIA/gr-dvbt

It will be very helpful and
appreciated if you help me. If

someone tested it or can do
it, please let me know. As far as I

know someone tested it with
N210 model.

I think this failure is due
to high noise/interference or smt.

else. However I tested it
already with all possible

configurations. I also
attach my .grc files.

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