Would it be possible to get a visualizer like the THD bar graph, but showing 1/3 octave bars?
Hi @Westerdahl, it’s definitely possible. I think the idea of octave made sense a long time ago before DSP was really practical and the spectrum displays was implemented with analog filter banks. But with DSP, we can get much better clarity. What specifically are you thinking about?
Hi matt,
The standard that I am testing against requires to do the measurement in 1/3 octave bands for some of the tests.
IEC 60645-1:2017 eg. clause 5.7.2
BR, Westerdahl
Hi @Westerdahl, yes, I see your point as talk of octaves is rampant throughout the standards. Would it be suitable to have a visualizer that could report the energy in each band? You specify the octaves and start freq (eq 1 octave starting at 20 Hz) and then the energy in each span is reported as a bar graph? Currently it would be very hard to get on the main display.
Hi Matt,
Yes I can live with a visualizer as long it can show each band in dB’s.
Is it possible to use cursors on the visualizer?
BR, Westerdahl
Hi @Westerdahl, I think it will look a bit like below. You have the ability to specify channel, octaves per bin, the start freq, number of bins, and then the end freq is calculated for you. If you right click on the graph, you can display values of each bin. You can see the energy in the bin hovered over in this case -100.1 dBV.
This currently shows “Energy (dBV)” but that’s a bug and will be fixed. The correct Y axis is Amplitude (dBV). For example, the first bin is 20-40 Hz (one octave). If you make an RMS measurement set from 20 to 40 Hz, it will report the same number as shown in the bar.
Maybe it would be useful to have the level of each bar shown and have that turned on/off by the user. If you pick L+R and 1/3 octave, it’s a lot of bins and hard to make sense of the level of each bar. But if the user can enable/disable the option, it might be OK? What do you think?
Hi Matt,
Looks good.
It would be very nice if we could say lock to one bin eg. 1 kHz and then when you hover over another bin it will show the energy and the delta to the 1 kHz bin. In that way I do not think I need to have the energy for each bin.
BR, Westerdahl