Apparatus for distinguishing between speech and certain other signals

摘要: Apparatus for distinguishing between speech and, example, data and noise signals, example use in a non-speech squelch circuit broadcast receiver, utilises the fact that an autocorrelogram of signal exhibits peaks which wander backwards forwards along delay axis, this not being case autocorrelograms most other signals. Autocorrelograms input applied to terminal (1) hard-limited by means comparator (5) are formed under control computer (14) shift register (3), multiplexer (10) inverting EXOR-gate (7), up/down counter(19) memory (41). For each clock pulse fed (30) output (11) multiplexer, hence one EXOR-gate, is switched succession taps (8) on register. Thus first tap (6) multiplied signals results used increment or decrement corresponding quantities (41) counter (19), relating successive periods time way determines positions (if any) comparison these whether they stationary wandering.