64 QAM-FM MODULATED DIGITAL MULTIPLE TRANSMISSION SYSTEM

摘要

PROBLEM TO BE SOLVED: To prevent deterioration of a CN ratio due to long-distance transmission, rain, etc., by converting an analog video and audio signals into an MPEG-2 transport stream (MPEG-2TS) signal and using 64 QAM modulation in a primary modulator and a microwave band FM modulation in a secondary modulator. SOLUTION: A CS digital tuner 3 demodulates a modulated signal from a parabolic antenna 1, converts it into a digital MPEG-2TS signal and output it. A real time encoder 4 converts analog video and audio signals from a camera 2 into an MPEG-2TS signal and outputs it. A digital multiplexer 5 digitally multiplexes the MPEG-2TS signal. A 64 QAM modulator 6 is a primary modulator which modulates a multiplexed signal from the multiplexer 5 into digital phase and amplitude signals and a microwave is modulated with an FM modulator that is a secondary modulator according to a 64 QAM signal from the modulator 6, and is transmitted by a microwave band transmitter 7.