Demodulating method of fsk signal

Abstract

Abstract PURPOSE:To make it possible to obtain the change point of the state of a modula- tion signal accurately, by measuring the period between two binary signals different from each other. CONSTITUTION:White-and-black television signal (a) is subjected to FSK modulation by frequencies fA and fB corresponding to binaries A and B, and periods of fA and fB are denoted as TA and TB respectively. The time for T1 TB of the period of the carrier wave for state transfer A B and the time for TB TA of the period of the carrier wave for state transfer B A are denoted as TAB and TBA respectively. TAB is a time based on TA before the change point of the state and is a time based on TB after the change point of the state. Since relational expressions (1) and (2) are true in respect to TA, TB, TAB, and TBA, times 95 and 96 for change A B and change B A can be detected accurately. As a result, states of binaries A and B can be demodulated accurately.

Inventors

• 👤 Hideji Yanase

Bibliographic Details