| 摘要 |
A modulator is adapted for use in a transmitter of an information transmission signal in which the information is in the form of a frequency shift keyed code. The signal is centered on a fictional carrier frequency fc, on either side of which are emitted two actual frequencies separated from the frequency fc by DELTA f, according to whether the binary information has a high value (+1) or a low value (-1). A first generator (1) creates carrier signals in the form of sin(2 pi fct) and cos(2 pi fct). A second generator (6) creates, as a function of the information, modulation signals of the form sin(2 pi DELTA ft) and cos(2 pi DELTA ft) which are mixed with the carrier signals. At each transition of the information, first phase shifting means (8,14) modify by k pi the phase of one of the modulation signals. Second phase shifting means (8,9,10,12), simultaneously with the action of the first phase shifting means and at each transition of the information, change the sign of the argument of the modulation signals. The carrier signal is thus devoid of phase jumps.
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