GNU Radio conditional operation

GNU Radio
1

Hi,

I’m wondering whether I can use GNU Radio with conditional operation

For example,

Listens signal, and if preamble received, skip preamble and continue
listening
if payload received, store it into file sink

Like that.

Currently, I use GNU Radio with USRPs just sending and receiving a
sequence.

2

On Wed, Apr 27, 2011 at 08:54:15PM +0900, Songsong G. wrote:

if payload received, store it into file sink

Like that.

Hi Songsong G.,

when using gr_blocks, you can do all kinds of stuff like that. Remember
that you can output pretty much anything when receiving something. So
you could write a block that simply doesn’t output anything as long as
no payload is being pushed into its input.

There are some examples for this. Check out
gnuradio-examples/python/digital.

MB

–
Karlsruhe Institute of Technology (KIT)
Communications Engineering Lab (CEL)

Dipl.-Ing. Martin B.
Research Associate

Kaiserstraße 12
Building 05.01
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Phone: +49 721 608-43790
Fax: +49 721 608-46071
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KIT – University of the State of Baden-Württemberg and
National Laboratory of the Helmholtz Association

3

Thank you for your answer.

I have one more question,
In that directory, there are lots of python script,
Unfortunately, I’m not good at that language
and I have just learned GNU Radio with GRC

Is that what I wanted now available in GRC?

2011/4/27 Martin B. [email protected]

4

Hi Marcus and the folks at Ettus,

I am an extremely satisfied and happy user of your USRP’s. We plan on
buying a lot more USRP’s for our company since it is an outstanding cost
effective platform for testing and measurements.

However if I have to offer some criticism (and I assure you that this is
the only complaint that I have amidst all the good things i have to
say), it is about the threadbare documentation available on getting
started with doing applications - whether that be for GRC, or python
programming for the USRP. I had to google the web for some examples and
this is how I learnt. There has to be a much easier way to getting
started. The folks at Ettus attribute too much intelligence to the
average user if this how they expect people to learn; it is actually a
disservice to Ettus as a company to make it so hard to start using your
products.

Hope what i have said above does not in any way detract from the overall
considerably positive feedback that i would like to convey.

Best regards,
-Vijay

— On Wed, 4/27/11, Marcus D. Leech [email protected] wrote:

From: Marcus D. Leech [email protected]
Subject: Re: [Discuss-gnuradio] GNU Radio conditional operation
To: [email protected]
Date: Wednesday, April 27, 2011, 12:40 PM

On 27/04/2011 12:27 PM, Songsong G. wrote:

Thank you for your answer.

I have one more question,
In that directory, there are lots of python script,
Unfortunately, I’m not good at that language
and I have just learned GNU Radio with GRC

Is that what I wanted now available in GRC?

Generally, custom processing blocks, which is what you’ll likely be
having to do, are written in C++.

In Gnu Radio, the Python is used as a kind of “glue” that sets up and
“manages” flow-graphs, but the
underlying signal-processing elements, and buffer and task scheduling
is generally handled in C code.
The vast majority of those blocks have mappings into Python (via Swig)
to allow the Python
``management` structure to manage them.

GRC emits Python code, using the underlying Gnu Radio conventions and
mechanisms to form a flow-graph.

Blocks you write yourself can be manifested (via Swig) into Python,
and then manifested via XML into
GRC.

The XML that GRC uses exists as a way of describing the surface of a
processing block, and also as a way of
describing the Python code that must be emitted in order to plug the
block into the overall flow-graph.

5

On 27/04/2011 12:27 PM, Songsong G. wrote:

Thank you for your answer.

I have one more question,
In that directory, there are lots of python script,
Unfortunately, I’m not good at that language
and I have just learned GNU Radio with GRC

Is that what I wanted now available in GRC?

Generally, custom processing blocks, which is what you’ll likely be
having to do, are written in C++.

In Gnu Radio, the Python is used as a kind of “glue” that sets up and
“manages” flow-graphs, but the
underlying signal-processing elements, and buffer and task scheduling
is generally handled in C code.
The vast majority of those blocks have mappings into Python (via
Swig) to allow the Python
``management` structure to manage them.

GRC emits Python code, using the underlying Gnu Radio conventions and
mechanisms to form a flow-graph.

Blocks you write yourself can be manifested (via Swig) into Python,
and then manifested via XML into
GRC.

The XML that GRC uses exists as a way of describing the surface of a
processing block, and also as a way of
describing the Python code that must be emitted in order to plug the
block into the overall flow-graph.

6

On 04/27/2011 03:00 PM, Vijay P. wrote:

programming for the USRP. I had to google the web for some examples and
-Vijay
Vijay,

Thank you for both your kind words and for the constructive feedback. I
agree fully that our documentation certainly could be better. We have
been trying to remedy that, and I believe that the UHD and basic
hardware documentation is reasonably complete:

http://www.ettus.com/uhd_docs/manual/html/

However, it does not address using GNU Radio with UHD or creating GRC
applications, so this is definitely the next area which we will be
covering. One other thing in the works is a screencast of creating some
simple applications using GRC.

Thanks,
Matt

7

I recently started using the USRP at work, so I thought I’d share a few
things. Obviously python is important (http://diveintopython.org/ is a
good
resource). To learn the basics of how gnuradio works, it helped me to
use
gnuradio-companion. So what I would do is put together some blocks in
grc
and look at the generated python code. I’ve been writing my experiences
on
my blog which some might find useful (
Intro to GNURadio and USRP | PwnHome Research). I am not an RF guy (CS
background), so there are a lot of things that I still don’t understand,
but
hopefully this will help.

8

On 04/28/2011 02:06 PM, Matt E. wrote:

On 04/27/2011 03:00 PM, Vijay P. wrote:

Hi Marcus and the folks at Ettus,

…

However, it does not address using GNU Radio with UHD or creating GRC
applications, so this is definitely the next area which we will be
covering. One other thing in the works is a screencast of creating some
simple applications using GRC.

I feel someone should point out the GNU Radio is a community project,
not an Ettus sponsored project. So it is up to everyone on this list to
help improve the GNU Radio new users experience.

Philip