Spectrum Analyzer datalogging

[VirtinsTech]

It is possible to log the sound level (dB) in any user specified frequency band. Just leave the X Scale of the Spectrum Analyzer in Linear or Log mode (right click anywhere within the Spectrum Analyzer window and choose [Spectrum Analyzer X Scale]), and then go to [Spectrum Analyzer Processing] and select "Energy in User Defined Frequency Bands". You can define up to 8 frequency bands per channel and these values can be accessed via Derived Data Points (DDPs): fBand1RMS_A(EU)~fBand8RMS_A(EU), fBand1RMS_B(EU)~fBand8RMS_B(EU).

If you want to log the sound level (dB) of an octave band, you need to know the low and high limits of that octave band. They can be calculated as follows, given the center frequency of that octave band:

fn_lowlimit = fn / sqrt(2)
fn_highlimit = fn x sqrt(2)
where fn is the center frequency of the octave band. In Multi-Instrument, you can get the center frequency of an octave band by putting the cursor on it and pressing down the left key of the mouse (the Spectrum Analyzer X Scale should be in octave mode).

Once you get the low and high limits of an octave band, you can then use the "Energy in User Defined Frequency Bands" function to get the energy contained in that frequency band (the Spectrum Analyzer X Scale should be in linear or log mode).