FM SIGNAL DEMODULATING METHOD USING WIDE BAND 90amp;deg; PHASE SHIFTER AND DEVICE THEREFOR

摘要

PROBLEM TO BE SOLVED: To provide an FM (frequency modulated) signal demodulating method using a wide band 90° phase shifter and a method thereof, which has a characteristic in which an output is smoothly saturated for frequency deviation largely exceeding a range to be demodulated.;SOLUTION: The FM signal demodulating method using a wide band 90° phase shifter, is characterised in that reference signals having frequencies whose phases differ by 90° from each other in the center frequency of an FM signal to be demodulated are subjected to frequency mixing with inputted FM signals respectively, and are converted to intermediate frequency signals I and Q whose phases differ by 90° from each other centered at 0 Hz, four kinds of signals IS, IC and QS, QC obtained by operating the phases of each of the intermediate frequency signals I and Q by the wide band 90° phase shifter are generated, and an operation IS×QC-IC×QS between these signals is outputted.;COPYRIGHT: (C)2005,JPO&NCIPI