MODULATION CIRCUIT AND SIGNAL MODULATION METHOD

摘要

PROBLEM TO BE SOLVED: To provide a modulation circuit that can emit a large power in excess of a maximum electric field strength in comparison with a conventional modulation circuit even in the case of wireless communication using a very weak radio wave or the like where the maximum electric field strength is limited and allows a receiver side to use a conventional ASK demodulator with low power and to demodulate the signal without the need for a matched filter needing a high power and to provide a signal modulation method. SOLUTION: The modulation circuit includes an FM modulation means that applies FM modulation to a first carrier with a noise whose spectral is widely spread or a signal whose spectral is widely spread and whose power is concentrated on a particular frequency and outputs a second carrier, and an ASK modulation means that applies ASK modulation to the second carrier outputted from the FM modulation means by using a first digital signal.