Signal compressors and expanders

Abstract

Abstract CHARACTERISTIC SAID SECOND FILTER INCLUDING A VARIABLE IMPEDANCE MEANS RESPONSIVE TO AN INCREASE IN THE AMPLITUDE OF AT LEAST ONE OF THE OUTPUT OF AND THE INPUT TO SAID FURTHER SIGNAL PATH FOR ALTERING SAID CUTOFF CHARACTERISTICS FROM WIDE BAND PASS UNDER VERY LOW INPUT SIGNAL CONDITIONS TO PROGRESSIVELY NARROWER BAND PASS, PROVIDING A CUTOFF FREQUENCY WHICH SHIFTS AWAY FROM SAID SECOND LIMIT SUFFICIENTLY TO ATTENUATE, IN COMBINATION WITH THE SAID CHARACTERISTICS OF SAID FIRST FILTER, ANY HIGH-LEVEL INPUT SIGNAL COMPONENTS AT ANY GIVEN FREQUENCY IN SAID SPECIFIED FREQUENCY BAND TO A SPECIFIED LEVEL CORRESPONDING IN SAID SECOND SIGNAL TO A SMALL FRACTIONAL PART OF THE MAXIMUM LEVEL OF SAID INPUT SIGNAL, WHILE PERMITTING INPUT SIGNAL COMPONENTS BELOW SAID SPECIFIED LEVEL AT FREQUENCIES NEARER TO SAID FIRST LIMIT THEN SAID GIVEN FREQUENCY TO PASS THROUGH SAID FILTERS AND TO APPEAR IN SAID SECOND SIGNAL WITH A LESSER DEGREE OF ATTENUATION. 1. A SIGNAL PROCESSING SYSTEM FOR PRODUCING AN OUTPUT SIGNAL IN RESPONSE TO AN INPUT SIGNAL COMPRISING A MAIN SIGNAL PATH RESPONSIVE TO SAID INPUT SIGNAL AND INCLUDING MEANS FOR PROVIDING IN A SPECIFIED FREQUENCY BAND EXTENDING BETWEEN FIRST AND SECOND LIMITS A FIRST SIGNAL SUBSTANTIALLY PROPORTIONAL TO SAID INPUT SIGNAL, A FURTHER SIGNAL PATH COUPLED TO SAID MAIN SIGNAL PATH AND RESPONSIVE TO A SIGNAL DERIVED FROM SAID MAIN SIGNAL PATH FOR PRODUCING A SECOND SIGNAL IN SAID SPECIFIED FREQUENCY BAND, AND SIGNAL COMBINING MEANS FOR COMBINING SAID FIRST AND SECOND SIGNALS TO PRODUCE SAID OUTPUT SIGNAL, SAID FURTHER SIGNAL PATH INCLUDING A FIRST FILTER HAVING FIXED VALUE COMPONENTS FOR PROVIDING PASS CHARACTERISTICS IN A FIXED BAND EXTENDING FROM SAID FIRST LIMIT TO A CUTOFF FREQUENCY INTERMEDIATE SAID FIRST LIMIT AND SAID SECOND LIMIT; AND MEANS FOR LIMITING THE AMPLITUDE OF THE OUTPUT SIGNAL OF THE FURTHER SIGNAL PATH, SAID MEANS INCLUDING A SECOND FILTER CONNECTED IN CASCADE WITH SAID FIRST FILTER AND HAVING VARIABLE CUTOFF

Inventors

No inventors recorded.

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