Signal processing units (SPUnits) provide the S_TOOLS-STx programmer with the possibility to create their own signal processing algorithms. Using a set of predefined atoms, the programmer can develop such things as a synthesis circuit (e.g. sample generators by additive synthesis), a real-time spectrum analyzer (using SPECTRUM and WAVEIN atoms) or a complete speech analysis (e.g. by using the atoms F0SIFT, RMS and LPCOEFS).
SPUnits are defined using the S_TOOLS-STx signal processing language. Once defined, they can be instantiated in an SPUnit item, or used as an 'atom' in another SPUnit.