[Discuss-gnuradio] PSK31 dynamic TX flow

[Louis Brown]

I'm experimenting with PSK31 transmission.  I can transmit bits streamed from a 
file, but to take it to the next level, I need to dynamically switch between 
keyboard keystroke generated data and a repetitive 1010 without stopping the 
flow.

Is there a way in GRC (or the main GR python script) to dynamically select 
between a signal source and a file source, using the signal source when the 
file source is empty?  The file source would be a FIFO that I would fill with 
an external python script that translates keyboard strokes into a varicoded bit 
stream.  When that FIFO is empty I need to switch back to the alternating 1010. 
 I'd rather not source the 1010 from the FIFO since that may lead to timing 
issues.

I'm trying to avoid, in the short term, writing a custom GR source block, but 
that may be inevitable.  I read there is a way to probe data in the flow; is 
there a way to stuff bits into a stream?

Thanks,
Lou