On Tue, Aug 13, 2013 at 6:34 PM, Tom McDermott <tom.mcdermo...@yahoo.com> wrote: > Hi, > > Recently upgraded to GRC 3.7 (from 3.6.5). The QT GUI Sink Frequency Display: > Center > Frequency (Hz) control and the 'Display RF Frequencies' checkbox do not seem > to be > operating correctly in GRC 3.7. > > In GRC 3.6, Center Frequency (on the block properties) had no effect on the > actual display. > If a value was entered in Center Frequency (Hz), there was no change to the > display at all. > If the 'Display RF Frequencies' checkbox was checked and a non-zero value was > in the > Center Frequency (Hz) block, then the display did not change, but the X-Axis > labels were > changed to the sum of (display + Center Frequency). I think this agrees with > the > documentation. This was very useful for example as the NCO frequency of a > down-converting > receiver could be entered in the Center Frequency box, and when 'Display RF > Frequencies' > box was checked, the frequency display would show the actual RF frequency of > the signal prior > to downconversion. Searching the discuss-gnuradio archives on the topic > revealed the last > post on this topic in 2011, and that this seemed to be the intended operation > of the controls. > > In GRC 3.7 however it does not work this way. Placing a value in Center > Frequency (Hz) shifts > the graphical display. If Center Frequency has a value greater than the > display width, then > in fact nothing at all is displayed on the graph (it would all be shifted > past the right side). The X-Axis > labels are altered whether or not the Display RF Frequencies checkbox is > selected. For > example: a 10 KHz complex waveform shows a single peak at 10 KHz when Center > Frequency = 0. But if Center Frequency = 10000 is selected (Display RF = > off), then the single > peak is shifted to the right on the display, and appears over the 20000 Hz > indicator. The display > range is labeled -6 to +26 KHz. For the above, when Display RF Frequencies is > selected, the > X-Axis displays +5 to +15 KHz, and the single peak shows at a frequency of > 11.56 KHz. > > I've tried to think of the ways that these controls might have been > repurposed, but can't come up > with a combination that would give this behavior, so assume that it may be a > bug. The way > it worked in GRC 3.6 would be desired behavior. > > Below is the simple GRC 3.7 flowgraph to demonstrate: > (Signal Source (complex) -> throttle (complex) -> QT GUI Sink (complex)). > > > Thanks. > > -- Tom, N5EG
I just pushed a fix for this to our git repo yesterday. Silly bug between Qwt 5.2 and 6 for handling the zoomer object. -- Tom Visit us at GRCon13 Oct. 1 - 4 http://www.trondeau.com/grcon13 _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
