ITU speech coders for gnuradio

GNU Radio
1

Hi All,

I’m using Ubuntu 9.10, gnuradio version 3.2.2 and two USRP2 boards
with XCVR2450 daughter boards.

I would like to establish G.711 encoded voice communication between
the two USRPs. I tested the link with tx_voice.py and rx_voice.py
example scripts and the Full Rate GSM encoding works fine. However, I
don’t see a python interface for ITU speech coders (G.711, G.721,
etc.) although there are appropriately named C files in
gnuradio-core/src/lib/g72x directory. I’m really curious about these
files as I can’t see g72x.h being used anywhere in the gnuradio code.

Are there any plans for a g72x interface?

Also, if there is anyone with experience in voice over gnuradio, any
suggestions are highly appreciated.

Thank you,

Veljko

2

On Thu, Jan 07, 2010 at 10:21:14AM -0800, Veljko P. wrote:

gnuradio-core/src/lib/g72x directory. I’m really curious about these
files as I can’t see g72x.h being used anywhere in the gnuradio code.

Are there any plans for a g72x interface?

Not in the sense of “Gee, it’s on my list of things to do” :wink:
But if you’re interested, you’re probably the right person to make it
happen!

Also, if there is anyone with experience in voice over gnuradio, any
suggestions are highly appreciated.

Thank you,
Veljko

Eric

3

On Thu, Jan 7, 2010 at 10:21, Veljko P. [email protected] wrote:

Also, if there is anyone with experience in voice over gnuradio, any
suggestions are highly appreciated.

I have successfully used the GSM and CVSD vocoder blocks in commercial
GNU Radio-based work. The tx_voice.py and rx_voice.py examples are
the right place to understand how they fit into an overall flowgraph.

I suggest, however, than unless you are already familiar with Python
programming, you start with grc for experimentation, as this is a
gentler learning curve and you can focus on DSP/GNU Radio blocks
design.

The CVSD blocks are in the current git version of grc, but the GSM
ones are not. Guess we should fix that.

There are no block wrappers around the G.7xx code in gnuradio-core.
That would be a good project to learn how to write custom blocks in
C++, and we’d welcome the contribution.

Johnathan

4

On Thu, Jan 7, 2010 at 11:29, Veljko P. [email protected] wrote:

I’ll see if I can write a wrapper. I assume that the G.7xx code in
gnuradio-core is working?

We assume so too. It’s all Sun developed CCITT reference code,
released into the public domain.

Johnathan

5

Thanks for the clarification.

I’ll see if I can write a wrapper. I assume that the G.7xx code in
gnuradio-core is working?

cheers,

Veljko

2010/1/7 Johnathan C. [email protected]:

6

hi all,
may be i am going to ask a stupid question but please answer it if
somebody
knows!!!

can any body tell what tools(hardware+software) are required to make a
commercial gsma5.1 interceptor

waiting for your answer