| 摘要 |
PURPOSE:To operate the title modulator even when a carrier frequency is lower than a half of the maximum frequency of a modulation signal by applying digital signal processing to a modulation wave and a carrier wave so as to produce directly a single side band wave signal without producing both side band signals. CONSTITUTION:A modulation signal is fed to a modulation signal input terminal 1 and a carrier is fed to a carrier input terminal 2. They are divided into two respectively, the one is fed respectively to the 1st and 2nd 90 deg. phase shifters 3, 4. Four kinds of analog signals in total; the modulation signal, the carrier, output signals of the phase shifters 3, 4, are converted into digital signals by the 1st-4th A/D converters 5-8. Output signals of the 1st and 3rd A/D converters 5, 7 are multiplied by the 1st multiplier 9, and digital output signals of the 2nd and 4th A/D converters 6, 8 are multiplied by the 2nd multiplier 10 respectively. Digital output signals of the multipliers 9, 10 are added by an adder 11, its output signal is converted into an analog signl by a A/D converter 12 and a single side band signal is outputted directly at an output terminal 13.
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