Re: [Discuss-gnuradio] gr_delay

[Marcus D. Leech]

On 11/02/2011 09:33 PM, Johnathan Corgan wrote:

On Wed, Nov 2, 2011 at 17:19, Marcus D. Leech <address@hidden> wrote:

 

Your assertion that "it does take effect eventually" appears to not be true in reality (at least in this little test graph) (attached).

Looking at the code, there's an inline function, set_delay, that calls set_history().  And the SWIG goop appears to be correct.

Quit finding bugs in years old, assumed working code!

:)

It looks like this has never worked, and maybe was never even implemented.  I'm combing through the appropriate archaeological strata in the tree to see if the needed handling was removed at some point, but it looks unlikely.

Johnathan

I even tried a quick "hack" that sets an "updated" flag, and at the top of the work function, calling set_history() on a d_pending
  delay value, and then immediately returning 0.  That did nothing useful.

If people have ever tried to use this for phased-array coarse delay setting in a dynamic sense, it never would have worked.

I want it for two-element interferometry (the nearly-degenerate-case of a phased array :-) ).  I can already do fine phase adjustment just using
  complex phase rotation, but coarse adjustment requires that delays be inserted.  I need to be able to do it dynamically.

One quick hack I tried was to have a bunch of delay blocks, each with their own initial delay setting, and then selecting which one
  I wanted.  That worked just fine.  So the initial set_history() appears to have the desired effect.

-- 
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org