[Discuss-gnuradio] Is there any way in GRC to send a finite pulse?

Is there any way in GRC to stop sending a signal? For example, I attach a snapshot of a simple GRC flowgraph with a 250 Hz cosine signal source outputting floats into an audio sink, and also into a file sink called "test.dat". Everything works fine and I see the output, and I can graph the file with a simple python script.

Is there any way in GRC to automatically stop the signal after some time, say a finite pulse? I don't want to send a continuous signal, but I want it to stop, say, after ten periods.

Now some of you (e.g., Josh) have pointed me to a way of using Python or C++ to maybe tag the last sample with an EOB metadata, and I will try this when I need to do something in Python or C++, but I don't understand how it would change anything in this particular flow graph. I mean, just coloring the last sample with an EOB tag won't stop the datafile from being populated by a continuous data stream.

I guess I don't understand why it should be so hard just using GRC to stop sending a signal after some time., or maybe it's easy, and I just don't get it. I know there is a burst tagger object in GRC that someone once mentioned in this group, but it was used to feed into the USRP, and I assume that the USRP knew somehow to stop reception? I guess I am confused, and need some kind of help in understanding this. :-(.

Thanks for any insights....

From:	Bill Peter
Subject:	[Discuss-gnuradio] Is there any way in GRC to send a finite pulse?
Date:	Wed, 30 Jan 2013 19:07:28 -0500