Re: [Discuss-gnuradio] Implementing controlled transmission

[Eric Blossom]

On Tue, Oct 07, 2008 at 07:35:43AM -0700, kaleem ahmad wrote:
> 
> Hi,
> 
> I am using RFX2400+USRP+SUSI
> 
> I am using following flowgraph to transmit data:
> 
> gr.file_source -> gr.simple_framer -> gr.bytes_to_syms ->
> gr.interp_fir_filter_fff -> gr.frequency_modulator_fc ->
> gr.multiply_const_cc -> usrp.sink_c
> 
> When I start the flowgraph by either start() or run() or MainLoop(), the
> data is sent sussessfully for once if repeat option is False in file_source
> or continuesly if repeat option is True.
> 
> Actually I want to implement cyclic transmission (different from
> gr.file_source.repeat=True) in such a way that whenever I want I can again
> send data from that file (But if and only if I want, so I need control over
> data transmission which I cant by just setting repeat in file_source=True )
> 
> But the problem is that the graph gets complete when data in the file is
> finished and I cant ask the flowgraph to retransmit the data in the file. I
> want to have an implementation where I could dictate the graph to transmit
> data (externally, just like setting the frequency or gain while the graph is
> still running). Furthermore is it possible to change the file name
> externally while the graph is still running.
> 
> Any suggestions!!!!
> 
> Best Regards

Use a source that blocks when there's nothing in it.
This could be a gr.file_source connected to a named pipe, or a
file_descriptor_source connected to a pipe or socket.
Then write into the other end of the connection when you want to send
something.

Eric