Fg.run() doesn't return if gr.head() is used

GNU Radio
1

Hey Guys

I used gr.head() as my source, so I assumed fg.run() should be able to
return, but it doesn’t. Anybody has any idea which could be the reason?
Here
is the error message if I press ctrl+C to stop the program.

mygraph.run()

File
“/usr/local/lib/python2.5/site-packages/gnuradio/gr/flow_graph.py”,
line 113, in run
self.wait ()
File
“/usr/local/lib/python2.5/site-packages/gnuradio/gr/flow_graph.py”,
line 104, in wait
self.scheduler.wait ()
File
“/usr/local/lib/python2.5/site-packages/gnuradio/gr/scheduler.py”,
line 68, in wait
thread.join(timeout)
File “/usr/lib/python2.5/threading.py”, line 569, in join
self.__block.wait(delay)
File “/usr/lib/python2.5/threading.py”, line 233, in wait
_sleep(delay)
KeyboardInterrupt

Thanks.

Dawei

2

On Thu, Aug 09, 2007 at 09:32:56PM -0400, Dawei Shen wrote:

Hey Guys

I used gr.head() as my source, so I assumed fg.run() should be able to
return, but it doesn’t. Anybody has any idea which could be the reason? Here
is the error message if I press ctrl+C to stop the program.

It should stop. However, if you happen to be using gr.udp_source or
anything else that is in the habit of returning a zero count from
work, it won’t return.

Eric

3

Hi, Eric and Johnathan

Thank you guys for the quick answer. I have done some tests with my code
and
got the following observation: I used a low-pass filter in the
processing
chain, if the decimation rate is set to 1, then fg.run() can return; if
the
decimation rate is set to any other integers, fg.run() won’t. I am not
sure
whether this is something random in my machine or caused by the code
itself.

BTW: Eric, you mentioned the gr_udp_source, I am quite interested in it,
is
there any example in the svn using this block? If so, please point some
of
them to me. Thanks.

Dawei

4

Hi, Johnathan

Thank you for the answer. But what’s the difference between the new
blocks
and old blocks? Thanks.

Dawei

5

Dawei Shen wrote:

BTW: Eric, you mentioned the gr_udp_source, I am quite interested in it,
is there any example in the svn using this block? If so, please point
some of them to me. Thanks.

See gnuradio-examples/python/hier/networking.

These use the new-style flowgraph code, but you can see the
instantiation of gr.udp_source and _sink and how they are used.

–
Johnathan C.
Corgan Enterprises LLC
http://corganenterprises.com