| 摘要 |
1. In combination, means to generate a first noise signal having predetermined characteristics, means to generate a second noise signal having predetermined characteristics different from that of said first noise signal, means to generate a carrier wave, means to generate a message signal, means to modulate said first noise signal with said carrier wave in the presence of said message signal to derive a first modulated wave, means to modulate said second noise signal with said carrier wave in the absence of said message signal to derive a second modulated wave, means to suppress said carrier wave in said first and second modulated wave, means to transmit at least one sideband of said first or second modulated wave, means to receive said transmitted wave, means for generating a second carrier wave, means for heterodying said received wave against said second carrier to derive a resultant signal of desired frequency, means for generating a third noise signal having the same amplitude characteristics as said first noise signal on a controllably variable time base, means for generating a fourth noise signal having the same amplitude characteristics as said second noise signal on a controllably variable time base, means for starting said third and fourth noise generators at the same point on the predetermined characteristic as the first and second noise generators, means for starting said third and fourth noise generators at a time determined by reception of said received wave, means for controlling the time base of said third and fourth noise signal to be identical with the time base of said first and second noise signal as received by the receiver, means for correlating said received wave with said third and fourth noise generator to derive said message signal.
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