Fsk receiver

Abstract

Abstract PURPOSE:To make the size of an FSK receiver small and to make the weight light by adopting the orthogonal detection reception system to omit a high frequency filter and an intermediate frequency filter requiring a large area. CONSTITUTION:A reception wave subject to frequency modulation by a binary digital signal is amplified by a high frequency amplifier 101 and inputted to a mixer circuit 102. Moreover, an output of a VCO 109 is given to a 90 deg. phase shifter 108, in which the phase is shifted by +45 deg. and -45 deg. and the result is inputted to the mixer circuit 102. The VCO 109 is controlled by an AFC circuit 110 and since the carrier frequency and the local oscillating frequency are coincident with each other, the base band signal is a beat frequency signal. An LPF 103 extracts only the base band signal to limit the band of noise and the result is inputted to a limiter circuit 104, where the signal is binarized and signals I, Q are obtained. Signals I, A are inputted to a demodulation circuit 105, where they are frequency-detected and demodulated by the demodulation circuit 105, given to an LPF 106 and a comparator circuit 107 obtains a binarized digital signal.

Inventors

• 👤 Yoichiro Minami
• 👤 南　洋一郎

Bibliographic Details