Signal communication capable of avoiding an audible reproduction of a sequency of information signals

Abstract From the Canadian patent

537126, Abstract of the Disclosure, In a communication system for use in transmitting a sequence of information signals in addition to a sequence of digital voice signals subjected to adaptive delta modulation the information, signal sequence is modulated by a phase modulator (51) of the transmitter section (11a) into a phase modulated signal sequence and is combined with the digital signals by a combining circuit (15) into output signals. The phase modulated signals might be sent through an ADM decoder (36) and a switch (44) of a receiver section (12a) to a loudspeaker (45) to be reproduced togeter with the digital voice signals. However such phase, modulated signals are not substantially …