What is the current status of the OFDM project? Is it such that I could
give it a try using a tunnel.py type setup over a shared wireline - or
at least over two separate RX/TX wires?
Last I heard the receiver and transmitter were working but not over the air.
Hello,
Who is doing the OFDM project? May I get some info on that, because my thesis
project is on the same and I would love help in this regard.
Thanks a lot.
Regards,
Kuntal
Need Mail bonding?
Go to
http://www.gnuradio.org/trac/browser/gnuradio/branches/developers/n4hy
is the trac and
svn co http://gnuradio.org/svn/gnuradio/branches/developers/n4hy/ofdm
gets you the source. I am merging the trunk into this about every 50
revisions unless I see major progress on mblock, usrp, etc that
Hi!
I kicked the can down the road with Matt Ettus and Tom Rondeau. We have
spent two weeks on this total and others are welcome to contribute. We
need to have the argument: How do we specify the constellations? How do
we map carrier usage (which are pilots, clocks, etc.)?
To open a
Hi!
So there is no obvious fault, e.g. that I set the wrong
decimation/interpolation rate? (the samplerate should be 400kS/s?)
I just compared tx_ofdm.dat, recorded in your simulation, to my
recorded file. Therefore I modified usrp_fft.py. In tx_ofdm.dat, it
shows a large frequency band in use,
Hi!
Just curious on the channel transfer function, I did some modification
on the ofdm simulation to see the magnitude and the argument. I am
inverting your equalizer coefficients (and actually scaling them down).
The coefficients of the region of interest in frequency domain are sent
out through
Hello,
I'm currently trying to make your ofdm simulation work with two usrp
rev4. The scripts benchmark_ofdm_tx.py and ...rx.py are modified in
order to send (I looked on the examples in the directory
examples/python/digital/).
Decimation rate ist 160, interpolation rate 320. Frequency 2.4G, two
-Original Message-
From: [EMAIL PROTECTED] [mailto:discuss-
[EMAIL PROTECTED] On Behalf Of Dominik Auras
Sent: Tuesday, February 27, 2007 10:09 AM
To: discuss-gnuradio@gnu.org
Subject: [Discuss-gnuradio] OFDM - on air?
Hello,
I'm currently trying to make your ofdm simulation
In the n4hy developers branch, we spent today adding some new code and
cleaning up a huge mess. The old temporary mess (ofdm2) is gone and
ofdm has replaced it. This was current with the trunk this after and
has the ofdm code. We transmitted with this in the lab today.
My apologies for
Robert McGwier wrote:
In the n4hy developers branch, we spent today adding some new code and
Congratulations on the cleanup!
What is ofdm? What is n4hy?
Chris
___
Discuss-gnuradio mailing list
Discuss-gnuradio@gnu.org
On Mon, Feb 19, 2007 at 05:13:28PM -0800, Chris Stankevitz wrote:
Robert McGwier wrote:
In the n4hy developers branch, we spent today adding some new code and
Congratulations on the cleanup!
What is ofdm?
http://en.wikipedia.org/wiki/Orthogonal_frequency-division_multiplexing
What
On Fri, Feb 16, 2007 at 09:56:39AM -0500, Brian Padalino wrote:
On 2/16/07, Tom Rondeau [EMAIL PROTECTED] wrote:
Our biggest concern will probably be getting the signal to work on the RFX
boards, which (I think) all have the same output amplifier stage. What we
do
with all of the modulators
-Original Message-
From: Brian Padalino [mailto:[EMAIL PROTECTED]
Sent: Thursday, February 15, 2007 3:15 PM
To: Tom Rondeau
Cc: gnuradio mailing list
Subject: Re: [Discuss-gnuradio] OFDM PHY (802.11) ?
On an semi-related note, which of the RF front end cards will work
On 2/16/07, Tom Rondeau [EMAIL PROTECTED] wrote:
Our biggest concern will probably be getting the signal to work on the RFX
boards, which (I think) all have the same output amplifier stage. What we do
with all of the modulators is scale it from +1 to -1 (even my QAM modulators
are normalized
Hi all,
Is the OFDM implementation (see below) compliant to that of 802.11 ?
http://gnuradio.org/trac/browser/gnuradio/branches/developers/n4hy/ofdm2/gnuradio-examples/python/ofdm
I am looking for source code which implements 802.11a scrambler,
convolution encoder etc .. I couldn't find it in
Shravan Rayanchu wrote:
Is the OFDM implementation (see below) compliant to that of 802.11 ?
http://gnuradio.org/trac/browser/gnuradio/branches/developers/n4hy/ofdm2/gnuradio-examples/python/ofdm
No. This is a work in progress implementation of a generic,
parameterized OFDM
-Original Message-
From: [EMAIL PROTECTED] [mailto:discuss-
[EMAIL PROTECTED] On Behalf Of Shravan Rayanchu
Sent: Thursday, February 15, 2007 2:56 PM
To: gnuradio mailing list
Subject: [Discuss-gnuradio] OFDM PHY (802.11) ?
Hi all,
Is the OFDM implementation (see below
On an semi-related note, which of the RF front end cards will work
with the OFDM waveform? From my understanding, it has a pretty high
peak-to-average ratio which might cause some problems with some
transmitters.
How are the floating point numbers calculated on the PC going to be
normalized
The OFDM work has begun under my (n4hy) branch. Next week it will
continue as I travel to Virginia Tech to work with Tom, Matt, and others
on this and other work.
When we have an OFDM transceiver and can drive one of the Flexible
boards from Matt on the air, we will move it into the trunk
[EMAIL PROTECTED] wrote:
I'm pretty new to gnu radio and I want to transmit an OFDM signal
using different modulation types (BPSK, QPSK, and 64-QAM). The
concept is pretty simple: read data, map it to a specified
constellation map, and then send it through an IFFT. I don't know if
this
Johnathan Corgan wrote:
[EMAIL PROTECTED] wrote:
I'm pretty new to gnu radio and I want to transmit an OFDM signal
using different modulation types (BPSK, QPSK, and 64-QAM). The
concept is pretty simple: read data, map it to a specified
constellation map, and then send it through an IFFT.
Robert McGwier wrote:
Like all things in branches, until they are not in branches, this is
absolutely development code and here is no guarantee of completeness
or even correctness. It is the reason for doing this kind of work in
branches rather than imposing it on everyone in the trunk.
In
I did a bootstrap, configure, make, make install on n4hy's tree and when I
try to run ofdm_benchmark_tx, I get
[EMAIL PROTECTED] ofdm]# ./benchmark_ofdm_tx.py
Traceback (most recent call last):
File ./benchmark_ofdm_tx.py, line 23, in ?
from gnuradio import gr, gru, modulation_utils
File
Brett Trotter wrote:
I did a bootstrap, configure, make, make install on n4hy's tree and when I
try to run ofdm_benchmark_tx, I get
[EMAIL PROTECTED] ofdm]# ./benchmark_ofdm_tx.py
Traceback (most recent call last):
File ./benchmark_ofdm_tx.py, line 23, in ?
from gnuradio import gr,
Brett Trotter wrote:
Replying to myself here, I heard from someone that I should do make
uninstall on the standard tree before doing make install on n4hy's tree. I
make uninstalled both just to make sure it was cleaned out, and toasted
/usr/local/lib/python2.4/site-packages/gnuradio (same for
On Fri, Jan 26, 2007 at 02:55:29PM -0800, Brett Trotter wrote:
Brett Trotter wrote:
I did a bootstrap, configure, make, make install on n4hy's tree and when I
try to run ofdm_benchmark_tx, I get
[EMAIL PROTECTED] ofdm]# ./benchmark_ofdm_tx.py
Traceback (most recent call last):
I am doubting the libtool error in this one. If you have the libtool
error, it shows up well before this. You cannot complete the make.
IF you cannot complete the make, and it dies in making the mblock
message block code, then you can go back to the pmt directory and in
that directory do
Robert McGwier-2 wrote:
I am doubting the libtool error in this one. If you have the libtool
error, it shows up well before this. You cannot complete the make.
IF you cannot complete the make, and it dies in making the mblock
message block code, then you can go back to the pmt
On Fri, Jan 26, 2007 at 06:25:29PM -0800, Brett Trotter wrote:
I took Dan Halperin's advice and totally deleted my build tree- I also
totally cleaned out all traces of gnuradio and re-checked out everything
from subversion and re-built (n4hy's tree) and am still missing
Hello,
if someone is interested in OFDM / DAB, I posted what I did so far
on http://www.1c3.de/gr-dab.tar.bz2.
It contains a small GI correlation based OFDM transmitter / receiver
for experiments, and a mode 2 DAB receiver (just displays the
constellation).
Jens
Hello,i'm an italian student and i'm studying gnu radio for writing my
future degree.I need that someone give me informations about how to write an ofdm
block that follow the 802.11g standards.. Thank you
___
Discuss-gnuradio mailing list
Hi Prateek,
yes - I sampled another radio station (this time at 1,5 GHz - broader
subcarriers) and the jitter was significantly reduced. I implemented
deinterleavingi, channel coding, and descrambling - but so far no success in
demodulating. Yesterday I wrote a sender to check my receiver but I
(comments inlined)
On Wed, Apr 05, 2006 at 02:02:23PM -0400, Robert McGwier wrote:
Yes. Here is what you are missing:
Let us concentrate (as does your nice animated gif) on one channel in
the OFDM.
Yes, what's depicted are all decoded symbols in one OFDM frame.
Let us suppose you have a
Achilleas,
thanks for your comments. I am beginning to like this problem, as it has
extended my knowlegde of OFDM tremendously - thanks everybody.
Nevertheless I'd like to see it solved. We have ruled out pretty much
every effect - I'm beginning to suspect that the transmitter actually sends
Achilleas,
my estimate is based on frequency domain correlation. Just count the
offset of the maximum (o). Then estimate the fractional offset (fo) by taking
the
value left (l) and right (r) of the maximum and calculate fo = (r-l)/(r+l).
To compensate substract the resulting frequency offset
Thanks for the reply! I'm really struggeling here...
Yes, I think this is a critical step. small letters are time domain and
capital letters are frequency domain.
x(n) --- X(k)
FFT
x(n-n') - e^(j*2*pi*n'*k/N) * X(k)
FFT
for one OFDM symbol, 0 =
Further more this means that the demodulated symbol (differences!) should
always have phase 0, pi/4, 2pi/4, 3pi/4 (plus a *constant* offset of pi/8).
But this offset is varying.
Am I right?
And why should the transmitter introduce a varying offset? The problem is
somewhere in the demodulation
Jens,
I got interested in this discussion and looked at the
standard briefly and at your matlab code.
I have a couple of initial points; I will spend more time sometime this
week on your code:
1) where in the standard it says that this is pi/4 DQPSK ?
I only saw that the modulation used is
Achilleas,
thanks for taking the time. My goal is to implement COFDM in gnuradio,
DAB is a nice start.
To your points:
I got interested in this discussion and looked at the
standard briefly and at your matlab code.
I have a couple of initial points; I will spend more time sometime this
Jens,
I used a complete ad-hoc method for automatic frequency estimation:
tracing the minimum ratio of the power of DC over the total power of the
remaining channels, averaged over all symbols in a frame.
Your estimate seems quite good!
I atatch the .m file
I have not tried anything with the
Prateek Dayal wrote:
On 4/4/06, *Robert McGwier* [EMAIL PROTECTED]
mailto:[EMAIL PROTECTED] wrote:
http://www.cds.caltech.edu/~yasi/publications.html
http://www.cds.caltech.edu/%7Eyasi/publications.html
Also for frequency offset, what really matters is not the frequency
offset in Hz,
Jens:
This pi/4-DQPSK. That means
New-symbol * (complex conjugate (Old-symbol)) is pi/4 modulo pi/2.
Are you taking this into account on both the transmitter and the
receiver and it in all of the bins before your inverse fft provides the
time domain signal to transmit would be my
To resample, I used the Matlab resample function
chunk_resamp = resample(chunk, 2048, 2000);
It's basically an FIR low-pass - phase is linear.
I'll try again today without resampling, but then the timing is
pretty much screwed up.
Jens
On Fri, Mar 31, 2006 at 04:28:14PM -0800, Eric Blossom
Well - you can download the standard at ETSI. It's open and published.
I don't know about the US.
On Fri, Mar 31, 2006 at 05:46:49PM -0500, Charles Swiger wrote:
On Fri, 2006-03-31 at 17:08 +0200, Jens Elsner wrote:
I sampled a local DAB radio station at 225.648 MHz, decimation factor 32
On Sat, 2006-04-01 at 10:53 +0200, Jens Elsner wrote:
Well - you can download the standard at ETSI. It's open and published.
I don't know about the US.
Ok - last time I asked about the US hdradio standard I got the
impression that the lower levels of the stack were for licensee
eyes only.
:
[chunk_filt, z] = filter(b,a,chunk,z);
This would cause phase discontinuities at the edges of each block.
-Clark
From: Jens Elsner [EMAIL PROTECTED]
To: discuss-gnuradio@gnu.org
Subject: Re: [Discuss-gnuradio] OFDM / DAB demodulation
Date: Sat, 1 Apr 2006 10:48:29 +0200
To resample, I used
You are absolutely right - the matlab code is attached.
You can get my sample data (local radio station, 3 MBytes) from
http://www.1c3.de/dab_ml.dat.bz2.
Jens
On Sat, Apr 01, 2006 at 10:27:57AM -0500, Robert McGwier wrote:
Why don't you allow us to provide you with help based on the reality as
On Sat, Apr 01, 2006 at 01:59:09PM -0800, Matt Ettus wrote:
Jens Elsner wrote:
I resampled all the data to do a proof-of-concept. The frames are
only a small part of the chunk variable. What I am getting is a
fairly nice pi/4 DPSK. Only that in between OFDM Symbols (there are
76 in a
Good morning,
I sampled a local DAB radio station at 225.648 MHz, decimation factor 32
with the USRP/tvrx.
DAB is using COFDM with pi/4-DPSK on 1536 subcarriers (see www.etsi.com,
standard
EN300401 for details). I wrote some Matlab code to demodulate the
signal. The data is resampled from 2 MHz
filter transition are distorting the final result.
-Clark
From: Jens Elsner [EMAIL PROTECTED]
To: discuss-gnuradio@gnu.org
Subject: Re: [Discuss-gnuradio] OFDM / DAB demodulation
Date: Fri, 31 Mar 2006 19:28:38 +0200
After some thinking: Could this be phase noise? If it is, which
oscillator
On Fri, 2006-03-31 at 17:08 +0200, Jens Elsner wrote:
I sampled a local DAB radio station at 225.648 MHz, decimation factor 32
with the USRP/tvrx.
DAB is using COFDM with pi/4-DPSK on 1536 subcarriers (see www.etsi.com,
standard
EN300401 for details). I wrote some Matlab code to
On Fri, Mar 31, 2006 at 05:10:40PM -0500, Clark Pope wrote:
I would doubt that unless your USRP is defective. The phase noise should
only become a major factor at baud rates below about 10 kbaud.
What's the actual bandwidth of the DAB signal? Did you try collecting at 4
MSPS and then
Hi everyone,In our group, we are trying to experiment with OFDM and want to setup an OFDM Tx/Rx chain and performs experiments and evaluate several synchronization (timing/frequency) and equalization algorithms. We finally want to be able to transmit/receive OTA at
2.4 Ghz ISM band. I saw some
Gang - Yesterday I finally figured out how to create a rudimentary
ofdm signal, and today I slapped a receiver together and was suprised to
see they actually (somewhat) work - at least it's something to work with
and play with parameters and see what happens. Currently using psk31
and gmsk
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