Re: [Discuss-gnuradio] Rearranging a running flow graph

[Eric Blossom]

On Sat, Mar 17, 2007 at 12:29:34PM +0100, Patrick Strasser wrote:
> Hello!
> 
> I'd like to construct a demo for grc which can switch between two or 
> more branches in a flow graph, like AM or FM: given a Signal, this would 
> be modulated by an FM and an AM branch, then one is selected for a 
> simulated channel (noise) and afterwards the signal is fed to either a 
> FM or a AM demodulator. I want easily switch between the two behaviours, 
> but am not shure about how to do this the Right Way.

I think the "right answer" will be available as soon as Johnathan
finishes the work on "disconnect" in the gr_hier_block2 stuff.  This
will replace the existing hierarchical blocks, and will treat both
gr_blocks and hierarchical blocks as first class objects, able to be
connected and disconnected on the fly.

Johnathan, any estimate as to when this will be ready?

> I'd do this now with multiplicators, but that introduces for every 
> branch a new block, and keeps the unused paths running, which is 
> rousource hungry (I don't have that much CPU power).

Yes.

> An other way would be to do disconnects and connects in the flow graph. 
> Is this a sensible way to go? Can I rearrange a running flow graph or do 
> I have to stop before rearranging and start the flow graph afterwards?
> Josh: What do you think about integrating this into grc?

Yes, see above.  The existing gr.hier_blocks don't handle disconnect well.

> The third possibility would be contruct a swtich block that takes n 
> inputs and has a method to select the input by a number. Would this be 
> possible an a way so that the not-to be consumed path temporarily 
> discontinues processing? On continuation, the interrupted path would 
> work with old data. Any way to flush this or are the buffers small 
> enough to neglect this effect? I guess this would also be true for 
> connect/disconnect.
> 
> Patrick

Eric