Having another Python gateway block problem

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.

On 12/19/2011 07:58 AM, Paul Miller wrote:

everything runs all peachy and everything lines up. All set.
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.

Are you positive that its not a problem with the gui sink itself. See
this bug: http://gnuradio.org/redmine/issues/464

One way around it would be to feed both float signals into a float to
complex. The wxgui sink block will not mess with the alignment of the
real/imag channels in a complex stream. See if that makes a difference.

-Josh

On Mon, Dec 19, 2011 at 10:54:02AM -0800, Josh B. wrote:

Are you positive that its not a problem with the gui sink itself. See
this bug: http://gnuradio.org/redmine/issues/464

One way around it would be to feed both float signals into a float to

Yeah, that’s the problem, thanks. The work around works,
suggesting the bug is the problem.

I never would have found that bug had I looked, since I’ve never
seen it with other blocks. Does this bug depend on what’s
feeding in? Did I just get lucky?


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