Re: [Discuss-gnuradio] dynamically changing delay in gr_delay (or history in any gr_block)

[Josh Blum]

On 11/15/2011 12:00 PM, Achilleas Anastasopoulos wrote:
> I made a simple example with a cosine and a delayed version of that
> going through
> a multiplier, and observing the output together with a slider that
> changes the delay dynamically.
> However i do not see any change (eg, elimination of the dc component
> when delay ~ pi/2).
> 
> 
> Looking at the code of the block gr_delay it shows that the delay can
> dynamically change
> and this results essentially in a call to set_history() in gr_block.
> Looking further into the set_history() method, it sets the private
> variable d_history.
> 
> The question is: does the dynamic change of history have any effect in 
> gr_block?
> What happens in the guts of the block when d_history changes?
> and why don't i see any effect in the example above?
> 

I dont think that set history works quite that way. I made a new delay
block in gr-basic. Demo in GRC attached. Here is the implementation:
http://gnuradio.org/cgit/jblum.git/tree/gr-basic/lib/gr_basic_delay.cc?h=gr_basic

-Josh

delaydemo.grc
Description: application/gnuradio-grc