Optimal detection method e.g. for dual-tone multi-frequency (DTMF) signals, involves projecting vectorial display of input signal into vector area adapted to DTMF signal so that energy of projected signal representation is determined

摘要

The method involves projecting a vectorial display of an input signal into a vector area adapted to a dual-tone multi-frequency (DTMF) signal (3) so that the energy of the projected signal representation is determined (4, 5). The energy is then consulted as decision criterion (6), whether in the input signal a DTMF signal is contained (7a). The nominal DTMF frequency is determined in accordance with International Telecommunication Union T (ITU-T) standard under a four-dimensional vector area.