Forum: GNU Radio Non-deterministic behavior

Dear all,
we are experiencing an undesired random behavior when we run an
offline OFDM flow graph.
Specifically, we store a transmitted sequence of packets in a *.dat
file (file_sink) and then we run the receiver chain using always the
same file as source (file_source).

Repeating several times the same run using the same source file, we
get a varying number of received right/wrong packets.

Is there an explanation to this behavior?
How can we generate a repeatable experiment?


Regards,
Vanessa

Hi,

Make sure you are using a 'throttle' block. Have a look at the 
following:

http://gnuradio.org/redmine/projects/gnuradio/wiki...


Mike
M0MIK

Yes, we are using a throttle but when we execute the same python file
we obtain always different outcomes.
We would like to have repeatable experiments.
Any tips?

Thank you
Vanessa

On Mon, Jan 28, 2013 at 5:46 PM, Mike Jameson <mikejamo@gmail.com> 
wrote:
> On 28 January 2013 16:40, Vanessa Gardellin <vanessa.gardellin@iit.cnr.it>
>> get a varying number of received right/wrong packets.
>> Discuss-gnuradio@gnu.org
>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>
>



--
Vanessa GARDELLIN, Ph.D.
Researcher
Institute for Informatics and Telematics (IIT),
Italian National Research Council (CNR)
Via G. Moruzzi 1
56124 Pisa - ITALY
Phone: +390503158297
Room: B65/c
E-mail: vanessa.gardellin@iit.cnr.it
WWW: http://www.iit.cnr.it/staff/vanessa.gardellin/
Skype: gardellin.vanessa

Hi Vanessa,

If you are using a random number generator, remember to save and re-use 
the
same 'seed' and also to reset it to the beginning of each run.

Mike
M0MIK

We do not have any random generator in the code that we wrote.
We generate 100 packets always of the same size and containing all "a".

Could it be something that depends on the scheduler or on how threads
are handled?

On Tue, Jan 29, 2013 at 12:09 PM, Mike Jameson <mikejamo@gmail.com> 
wrote:
> wrote:
>> > Hi,
>> > On 28 January 2013 16:40, Vanessa Gardellin
>> >> Repeating several times the same run using the same source file, we
>> >> Discuss-gnuradio mailing list
>> Institute for Informatics and Telematics (IIT),
>> Italian National Research Council (CNR)
>> Via G. Moruzzi 1
>> 56124 Pisa - ITALY
>> Phone: +390503158297
>> Room: B65/c
>> E-mail: vanessa.gardellin@iit.cnr.it
>> WWW: http://www.iit.cnr.it/staff/vanessa.gardellin/
>> Skype: gardellin.vanessa
>
>



--
Vanessa GARDELLIN, Ph.D.
Researcher
Institute for Informatics and Telematics (IIT),
Italian National Research Council (CNR)
Via G. Moruzzi 1
56124 Pisa - ITALY
Phone: +390503158297
Room: B65/c
E-mail: vanessa.gardellin@iit.cnr.it
WWW: http://www.iit.cnr.it/staff/vanessa.gardellin/
Skype: gardellin.vanessa

Hi Vanessa,

a question like this pops up every once in a while. Is your dat file
pretty large? This would fit with what others have been reporting.

Is there any way you could provide an example of something that is
failing?

Also, have you tried reducing the throttle to something pretty
ridiculously slow?

MB

On Mon, Jan 28, 2013 at 05:40:46PM +0100, Vanessa Gardellin wrote:
> Is there an explanation to this behavior?
> How can we generate a repeatable experiment?
>
>
> Regards,
> Vanessa
>
> _______________________________________________
> Discuss-gnuradio mailing list
> Discuss-gnuradio@gnu.org
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio

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

Dipl.-Ing. Martin Braun
Research Associate

Kaiserstraße 12
Building 05.01
76131 Karlsruhe

Phone: +49 721 608-43790
Fax: +49 721 608-46071
www.cel.kit.edu

KIT -- University of the State of Baden-Württemberg and
National Laboratory of the Helmholtz Association

No, I am not.

On Tue, Jan 29, 2013 at 4:01 PM, Marcus D. Leech <mleech@ripnet.com> 
wrote:
> Are you using a channel model in the middle of your simulation?
>
>
> _______________________________________________
> Discuss-gnuradio mailing list
> Discuss-gnuradio@gnu.org
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio



--
Vanessa GARDELLIN, Ph.D.
Researcher
Institute for Informatics and Telematics (IIT),
Italian National Research Council (CNR)
Via G. Moruzzi 1
56124 Pisa - ITALY
Phone: +390503158297
Room: B65/c
E-mail: vanessa.gardellin@iit.cnr.it
WWW: http://www.iit.cnr.it/staff/vanessa.gardellin/
Skype: gardellin.vanessa

This might be easier to get help with if you sent some code or a GRC
file. Or we can go with 21 questions in which case I have my own :-)

Are you getting any over/under flows (O's or U's being printed to
console) when you run the flowgraph? Any output at all?

On Thu, Jan 31, 2013 at 1:31 AM, Vanessa Gardellin