Spectrum Lab Glossary

< under construction >

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.
Digital- to Analog Converter. Used, for example, in the output section of a soundcard, to convert the processed signal back into analog audio signals.
Digital Signal Processing, or digital signal processor. In Spectrum Lab, DSP is done entirely in software (no "hardware DSP" is used here).
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.
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.
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").
Very Low Frequency = radio spectrum between 3 and 30 kHz. Can be processed directly with modern soundcards.