Circuit arrangement for the determination of the fundamental frequency of a non band-limited, harmonics - and interference signal hold strength signal, preferably for determining the vocal fundamental frequency from the voice for vocal fundamental frequency synchronous triggering of the flash tube of a laryngostroboskops

摘要

The circuit contains a low-pass filter (FI) with controllable limit frequency receiving an electrical tuning signal and followed by an amplifier (GV) regulated to a constant output voltage, a null crossing detector (ND) and an evaluation and control circuit (AS). The evaluation and control circuit is a microcomputer with evaluation and control algorithms controlling the limit frequency in a search and a control phase. The limit frequency is controlled so that the ratio of the limit frequency and the tuning frequency is less than 1:4 and is pref. 1.0. ADVANTAGE - Reliable extraction of coherent triggering signal is achieved under extremely unfavourable signal conditions.