Hello,

I am an electrical engineering student, and I would like to implement a

DAB receiver as a semester thesis (about 1/3 the size of a Master

thesis).

I intend to implement each part first in Matlab and then in GNU Radio.

Ideally, I hope to use the existing OFDM code in gnuradio-core and some

external MP2 library for the audio decoding.

However, I am wondering if this is feasible as a semester thesis. Any

comment about the rough amount of work that would be needed would be

greatly appreciated.

In the mailing lists, there are some references to an existing DAB

implementation from ([1],[2]). Can anyone tell me how far this got? The

referenced website (http://www.1c3.de/gr-dab.tar.bz2) is empty.

Regards, Andreas

[1]

http://lists.gnu.org/archive/html/discuss-gnuradio/2006-08/msg00205.html

[2]

http://lists.gnu.org/archive/html/discuss-gnuradio/2006-03/msg00397.html

Hallo Andreas,

with the current status of OFDM PHY code in GNU Radio I think it is

definately

worth a try.

The work I did on DAB was basically OFDM synchronization in one GNU

Radio block. The code was more or less a hack, but it deepened my

understanding of digital signal processing. Not as easy as in text

books. I’ll email the report to you separately.

I wouldn’t underestimate the complexities of the higher DAB layers,

it has quite a protocol stack. But you should give it a try. If you

need captured Mode I/II samples I can make them available for download.

Gruesse,

Jens

On Wed, Feb 20, 2008 at 07:14:24PM +0100, Andreas Müller wrote:

comment about the rough amount of work that would be needed would be

[2]

[Discuss-gnuradio] OFDM / DAB demodulation

Hello Jens

The work I did on DAB was basically OFDM synchronization in one GNU

Radio block. The code was more or less a hack, but it deepened my

understanding of digital signal processing. Not as easy as in text

books. I’ll email the report to you separately.

Thanks …

I wouldn’t underestimate the complexities of the higher DAB layers,

it has quite a protocol stack. But you should give it a try. If you

I actually did get a bit scared when I first looked at the 200 page

standard, but I hope that if I go for the “simplest possible” approach

for a start, a lot can be omitted (like service information). As DAB+

isn’t available here, I also intend to just go for DAB.

need captured Mode I/II samples I can make them available for download.

Thanks, but I can get quite a nice Mode I signal with the TVRX, so no

need…

Regards, Andreas

Hello Ravi

Ravi Trivedi wrote:

Hello all,

I am trying to implement synchronization of DAB receiver in matlab. I

have been facing some problems when I test the matlab receiver code for

real time streams.

First issue is sampling rate estimation problem. I see that real time

frame has shortage of samples when compared to values given in

specification. I do frame detection first followed by joint estimation

What is your sampling rate, and how many samples are you missing? It’s

likely that your sampling rate is not exactly what you expect, when you

use real-world data, and maybe you have to do sampling rate correction

as well.

of fine timing and coarse frequency offset. After compensation, I

perform fine frequency offset estimation and compensation. I see that

for real time streams FIC decoder doesn’t pass the CRC. If I use

simulated data CRC check gets passed.

Does anyone have receiver matlab code working for real time data which

I can use for comparison with my code? Thanks in advance.

I did an implementation for GNU Radio a while ago. You can find it at

[1] and a description in [2]. Although it’s not complete, it does

everything on the lower levels, up to (and including) FIC CRC

verification (which works, also with real-world data).

Regards, Andreas

[1] http://people.ee.ethz.ch/~andrmuel/files/gnuradio/gr-dab.tgz

[2] http://people.ee.ethz.ch/~andrmuel/files/gnuradio/dab-doc/thesis.pdf

Hello Andreas,

Sampling rate is 2.048Msps. When I analyze every DAB frame captured, I

see

that in total the whole frame has shortage of 9 to 10 samples. There

could

be a very high possibility due to ADC clock drift when we capture the

data

from DAB generator and digitize it.

Thanks for the references. I have developed the receiver side matlab

code

which works for simulated data. But I face issues in getting it working

for

real time streams. I need to add sampling rate converter in the code

which I

will be doing. You have mentioned in your thesis.pdf that you did refer

to a

matlab code for DAB receiver. If possible and if it’s not copyrighted

can

you share the same to me?

Best Regards

Ravi

Hello all,

I am trying to implement synchronization of DAB receiver in matlab. I

have been facing some problems when I test the matlab receiver code for

real time streams.

First issue is sampling rate estimation problem. I see that real time

frame has shortage of samples when compared to values given in

specification. I do frame detection first followed by joint estimation

of fine timing and coarse frequency offset. After compensation, I

perform fine frequency offset estimation and compensation. I see that

for real time streams FIC decoder doesn’t pass the CRC. If I use

simulated data CRC check gets passed.

Does anyone have receiver matlab code working for real time data which

I can use for comparison with my code? Thanks in advance.

Hello Andreas,

Sampling rate is 2.048Msps. When I analyze every DAB frame captured, I

see

that in total the whole frame has shortage of 9 to 10 samples. There

could

be a very high possibility due to ADC clock drift when we capture the

data

from DAB generator and digitize it.

Thanks for the references. I have developed the receiver side matlab

code

which works for simulated data. But I face issues in getting it working

for

real time streams. I need to add sampling rate converter in the code

which I

will be doing. You have mentioned in your thesis.pdf that you did refer

to a

matlab code for DAB receiver. If possible and if it’s not copyrighted

can

you share the same to me?

Best Regards

Ravi

Hello Ravi

Sampling rate is 2.048Msps. When I analyze every DAB frame captured, I see

that in total the whole frame has shortage of 9 to 10 samples. There could

be a very high possibility due to ADC clock drift when we capture the data

from DAB generator and digitize it.

Sounds reasonable - and afaik, 9 to 10 samples drift per frame could

corrupt

the signal enough to invalidate the CRC.

Thanks for the references. I have developed the receiver side matlab code

which works for simulated data. But I face issues in getting it working for

real time streams. I need to add sampling rate converter in the code which I

will be doing. You have mentioned in your thesis.pdf that you did refer to a

matlab code for DAB receiver. If possible and if it’s not copyrighted can

you share the same to me?

Unfortunately it is copyrighted, and I don’t have the permission of the

author to distribute it - but I’ll forward his email to you, you can try

asking him directly.

Regards, Andreas