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Re: [Discuss-gnuradio] synchronization between blocks
From: |
Michael Dickens |
Subject: |
Re: [Discuss-gnuradio] synchronization between blocks |
Date: |
Mon, 3 Feb 2014 14:30:48 -0500 |
On Feb 3, 2014, at 10:14 AM, Nemanja Savic <address@hidden> wrote:
> at the moment I thought that the problem was solved, but actually something
> strange is going on. I would only like to ask whether delay between two paths
> can roll out somehow (i don't know if this verb exists). The point is that at
> the beginig of the execution, it looks like the script is doing fine, but
> then I realize signs of unalligned signals which I can't in some other way.
IIRC: Because of the way GNU Radio internally handles data processing (it waits
for data upstream to become available before -starting- processing for a given
block), and since -your specific graph- contains only sync blocks (yes?), then
the sample delay difference between the 2 branches of -your specific graph-
should be constant. Further, it should be the same constant for every graph
execution.
If any blocks within a specific path are not sync blocks, e.g., a packet
decoder, then the sample delay difference is not guaranteed (constant or
otherwise).
The wall-clock delay difference will not be constant; it can be any
non-negative (and, generally > 0) time.
All of the above said: If you're into compiling GNU Radio, you can go into
gnuradio-runtime/lib/block_executor.cc and set "ENABLE_LOGGING" to 1.
Recompile/reinstall GNU Radio, then when you execute your graph you'll get a
printout dump of what each block is doing. That printout might help you debug
this issue; or, not. You might also add LOG messages in that file which could
help ... maybe; or, not.
Hope this helps! - MLD