JPS5511638A - Privacy circuit - Google Patents

Abstract

PURPOSE:To realize a simple and mineature structure for the circuit and unit as well as the quick alteration of the types of the private talk by using the transmission-side privacy circuit incorporating the delta modulator and demodulator plus the digital circuit and the reception-side privacy reproduction circuit. CONSTITUTION:Delta modulator 109 converts aural signal (a) supplied into binary pulse row signal (b). Divider circuit 110 regards the supplied signal (b) as (a) polynomial on the Galois substance and then divides it by the known polynomial to which only the coefficient is specified optionally to obtain the quotient. Pulse row signal (e) given from circuit 110 is suplied to delta demodulator 11 to be converted into analog signal (f). Signal (f) is then demodulated by the radio receiver to be changed into analog signal (g) and then to be supplied to delta modulator 209. Signal (h) which converted signal (g) into the binary pulse row is delivered from modulator 209 and then supplied to multiplier circuit 210. Here a multiplication which is exactly same as the polynomial of circuit 110 is carried out. Thus pulse row signal (k) delivered from circuit 210 is supplied to delta demodulator 211, and analog signal is delivered. Signal is the same as signal (a) transmitted.