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[Discuss-gnuradio] having another Python gateway block problem


From: Paul Miller
Subject: [Discuss-gnuradio] having another Python gateway block problem
Date: Mon, 19 Dec 2011 10:58:19 -0500
User-agent: Mutt/1.5.21 (2010-09-15)

If I'm doing something dumb, I can't find it.  Happens all the
time though.  I'm using the python_blocks branch
5cd66eef8ab8a81589dc08a134457d15b431434e .

I made a really simple sync_block that square-waves an input
signal.  I have a fancy block that does all kinds of things and I
think it's having the same sorts of trouble, but that thing's all
big.  This cute little block demonstrates the problem nicely.

Basically, what I'm seeing is that in QA tests with vector sinks,
everything runs all peachy and everything lines up.  All set.

But when I run my sync_blocks against a WX Scope, nothing lines
up right.  It's much less obvious when the input signal is well
behaved.  I imagined it was just lagging by a few items, but when
I mixed two non-harmonic waves, it was very clear that the
gateway block just didn't match up at all.

I have attached the block, a grc connector xml, the QA I used to
show that this doesn't happen with vector sinks, the gnuradio
companion diagram (png) and the gnuradio companion source file
I'm using.  (I hope attaching isn't rude on this list… if it is,
sorry in advance.)

The GRC program also has an add_const block in there (select with
variable).  Note that add_cost lines up perfectly, like we expect
but no amount of twiddling the connections (moving throttles,
removing switches, etc) will get the square-waver to line up with
the input signal.

-- 
If riding in an airplane is flying, then riding in a boat is swimming.
116 jumps, 48.6 minutes of freefall, 92.9 freefall miles.

Attachment: onesquare-test.grc.png
Description: PNG image

Attachment: onesquare-test.grc
Description: Text document

Attachment: onesquare.py
Description: Text Data

Attachment: onesquare.xml
Description: application/xml

Attachment: sq1.qa
Description: Text document


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