Spectrum Lab
Glossary
< under construction >

ADC

Analog to Digital Converter. Used, for example, in the input section of
a soundcard, to convert the analog audio signal into "numbers" which can
be processed with this program.

DAC

Digital to Analog Converter. Used, for example, in the output section of
a soundcard, to convert the processed signal back into analog audio signals.


DSP

Digital Signal Processing, or digital signal processor. In Spectrum Lab,
DSP is done entirely in software (no "hardware DSP" is used here).


ELF, SLF, ULF

Extremely Low Frequency: 3 ... 30 Hz, Super Low Frequency: 30 ... 300
Hz, Ultra Low Frequency: 300 ... 3000 Hz .
SLF and ULF can be easily processed with a soundcard. ELF can be a problem
due to the lower edge frequency of most soundcards, caused by the coupling
capacitors between the line input jack, and the ADC.

FFT

Fast Fourier Transform. An algorithm which can transform a signal from the
time domain into the frequency domain. The number of samples in the time
domain, and the number of samples in the frequency domain, are often restricted
to powers of two (as in SpecLab). The FFT is the heart of SpecLab's frequency
analyser, and also used in the DSP filter when running in "FFT mode". In
the SL manual, a single sample in the frequency domain (=often the "result"
of the FFT as we use it here) is often called an "FFT bin".


FFT bin (aka "FFT frequency bin", "Frequenzeimer")

A single bin in the fourier transform. Contains the energy of a signal in
a narrow frequency range.

LF

Low Frequency = radio spectrum between 30 and 300 kHz. This is beyond the
frequency range which can be handled with most audio soundcards, so you will
need an extra receiver to catch these signals. Some "shortwave" receivers
go down to 30 kHz, so they make decent LF receivers (but beware, their
sensitivity in the LF spectrum can be very limited, or, as radio amateurs
call it, they are "pretty deaf down there").


VLF

Very Low Frequency = radio spectrum between 3 and 30 kHz. Can be processed
directly with modern soundcards.