17
MORDAX : DATA
User Guide
SYS V. 01.00.00
BOOT V. 01.00.00
Updated: 161229
Program : Spectrum Analyzer & Spectrograph
One of the most interesting things about sounds (and periodic signals in general) is that they can be described as the sum of
an infinte set of sine waves at various frequencies and amplitudes. This collection of sine waves that make up a signal is the
signal’s frequency spectrum, and the individual sine waves in the spectrum are its harmonics (also called partials).
For example, a square wave can be created by starting
with a sine wave of a given frequency (the fundamental or
first harmonic), then adding subsequent sine waves at odd
multiples of the fundamental frequency and decreasing
amplitudes (odd harmonics). The green waveform right
shows the additive synthesis of a fundamental and three
additional odd harmonics (blue sine waves). It’s not a
perfect square wave, but it’s starting to take shape. If you
continued adding subsequent odd harmonics in this fashion
the combined wave to become increasingly more square, as
seen with the magenta wave, which is the result of 50 sine
waves combined.
The DATA’s spectral programs allow you to view these
frequency components, taking a time domain signal and
displaying it in frequency domain, showing it’s harmonic
content (the various sinewaves that make up the signal).
This is accomplished by Fourier analysis, specifically fast
Fourier transform (FFT). Both the DATA’s Spectrum Analyzer
and Spectrograph display the incoming signal’s frequency
spectrum, with the Spectrum Analyzer showing the output
of one FFT analysis at a time, and the Spectrograph
showing multiple FFT’s. The Spectrum Analyzer provides
the frequency components of a signal as a bar graph, with
each bar representing a small frequency range (also called a
bin); the higher the bar, and the lighter it’s color, the greater
the magnitude of the frequency band in the signal. The
Spectrograph shows the same information as the Spectrum
Analyzer, but only displays magnitude as a a function of
color.
RUN/STOP button:
Push to switch
between RUN and STOP of the display.
Peak Bin:
The tallest bar in the bar graph is the
frequency bin with the greatest magnitude. This is
the signal’s first harmonic (fundimental frequency).
Channel buttons:
The currently active input channel is highlighted. Push the
soft buttons below each channel number to change inputs.
Window Type:
Shows
the current windowing
function (filter) applied to
the incoming signal. Push
button 2-1 and scroll
with the encoder to apply
different window types.
