Meaning of Center Frequency in QT GUI Sink / QT Waterfall Sink

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1

Hi,

what is the meaning of the variable “Center Frequency” in the
qt_gui_sink / qt_waterfall_sink ?

If I remember well, in pre 3.7 version it served as base of the x -
axis legend.

Now, if I choose a value > bandwidth/2 the spectrum will not be
displayed.

Do I misinterpret the meaning of “Center Frequency” or is this a bug ?

– Volker

2

On Wed, Aug 14, 2013 at 6:29 AM, Volker S. [email protected] wrote:

Do I misinterpret the meaning of “Center Frequency” or is this a bug ?

– Volker

Volker,

This sounds like a bug. Someone else reported some related issues with
this sink in 3.7, too. Probably a versioning issue that I didn’t
properly take care of with the update.

Now, the main reason this would have slipped through is because I’m
trying to get rid of the qt_gui_sink. Since I’ve split out the
different sinks, it doesn’t make sense to keep them in two different
places with duplicated code that can’t easily be shared (which can
then lead to mistakes like this). I will be moving to a new structure
for the qtgui_sink_X blocks that is just a tab container for the other
individual classes to simplify the code.

Now, you’re also saying that it’s a problem with the
qt_waterfall_sink? That’s more surprising, but again, probably a
Qt/Qwt version issue and should be a simple fix once identified. Not
sure when I’ll be able to get to it, so either submit a patch or at
least open a bug report on our Issues Tracker to make sure I remember
to get to it soon.

But remember, setting the center frequency is just a display issue. It
simply sets the tick labels on the x-axis and nothing more.

–
Tom
Visit us at GRCon13 Oct. 1 - 4
http://www.trondeau.com/grcon13

3

Am 14.08.2013 23:45, schrieb Tom R.:

Now, the main reason this would have slipped through is because I’m
sure when I’ll be able to get to it, so either submit a patch or at
least open a bug report on our Issues Tracker to make sure I remember
to get to it soon.

But remember, setting the center frequency is just a display issue. It
simply sets the tick labels on the x-axis and nothing more.

Tom,

thanks for the info. I’ll see if I can fix it, otherwise I’ll report a
bug.

I’m using qwt-5.2 and pyqwt-5.2 on my system ( gentoo)

– Volker

4

On Fri, Aug 16, 2013 at 1:43 AM, Volker S. [email protected] wrote:

If I remember well, in pre 3.7 version it served as base of the x - axis
Volker,
for the qtgui_sink_X blocks that is just a tab container for the other
simply sets the tick labels on the x-axis and nothing more.

Tom,

thanks for the info. I’ll see if I can fix it, otherwise I’ll report a bug.

I’m using qwt-5.2 and pyqwt-5.2 on my system ( gentoo)

– Volker

Hi Volker,

Looks like this is specifically a Qwt 5.2 issue. I’ve resolved another
minor problem, but I’m seeing what you are seeing now by moving back
from Qwt 6. I’m working on a fix for it.

–
Tom
Visit us at GRCon13 Oct. 1 - 4
http://www.trondeau.com/grcon13