JPS5752238A - Radio receiving circuit - Google Patents

Abstract

PURPOSE:To obtain a radio receiving circuit which requires no adjustment, and has high accuracy and high reliability, by directly executing a digital conversion of a receiving high-frequency modulation or phase modulation signal. CONSTITUTION:A timing controlling circuit 43 for inputting a signal from a local oscillator 4, and a frequency digital converting circuit 12 for inputting a reference clock S2 from the circuit 43 and a signal from an intermediate frequency amplifier 7 are provided on the radio receiving circuit. On the circuit 12, a differentiating circuit 31 for sampling an input pulse number signal S1 of a pulse rate H, by an input clock of a pulse rate F from a timing generating circuit 34 for inputting the clock S2, a comparing circuit 32 to which an output of this circuit 31 is inputted, a counter 33 for counting an output pulse of this circuit 32, and a multiplier ML35 for receiving the pulse from the circuit 34 and generating a pulse in accordance with a counting value of the counter 33 are provided. The circuit 32 compares outputs of the circuit 31 and the ML35, increases or decreases the counting value of the counter 33 in accordance with a result of said comparison, and generates an output having magnitude corresponding to the frequency of the input pulse number signal.