Frequency stabilization circuit for local oscillator used in radio equipment

Abstract

Abstract PURPOSE:To realize highly precise frequency control with a small-scale circuit constitution by using a voltage varactor diode for a local oscillation circuit, and adjusting impressed voltage to the voltage varactor diode. CONSTITUTION:A receiving part 24 is constituted of an FSK demodulation circuit 1 and a phase detector 2, and a frequency control part 4 is constituted of a CPU 41 and a D/A converter 42, and a local oscillator 5 is constituted of the voltage varactor diode 51 and the local oscillation circuit 52. The number A of the leading parts of a signal Dq during a unit period of a modulation code '1' and the number B of the leading parts of the signal Dq during a unit period of the modulation code '0' are sampled N-times, and the respective mean values of A and B are calculated, and in the case of A=B, the CPU 41 keeps control voltage to the voltage varactor diode 51 at a constant value.

Inventors

• 👤 Yasunobu Watanabe
• 👤 渡邊　保信
• 👤 Kazuo Kawabata
• 👤 和生 川端

Bibliographic Details