Contents - Index

Measurement Accuracy

Frequency Accuracy:
The frequency accuracy depends directly on the accuracy of the sampling clock on the sound card.  This is typically a fraction of a Hertz (Hz).  You may wish to check your sound card by using a known signal source for comparison.  

Amplitude Accuracy:
By default, the analyzer is calibrated to show the relative power levels where 0dB is the strongest possible 16 or 24 bit signal.  It is possible to calibrate the amplitude axis by equating a known reference signal level with a measured sampling level; however, the frequency response of your sound card still comes into play.. 

Octave Scaling Accuracy:
Historically, spectrum analyzers have utilized analog filters for each band and standards (ANSI S1.11-2004) have been developed which specify the performance of these filters .  SpectraPLUS-RT uses a  Fast Fourier Transform (FFT) to compute the spectral data and then derives the octave data.  This algorithm uses the same ISO center frequencies and bandwidths as analog instruments; however, the FFT filtering method produces much steeper "shoulders".  These digital filters meet or exceed the performance of traditional analog filters.  

Dynamic Range:
The theoretical dynamic range of the system is as follows:
16 bit sampling precision = 96 dB
24 bit sampling precision = 144 dB
The actual dynamic range achieved is dependent upon the performance of your sound card.

See also:  Settings , Calibration