| 摘要 |
Transmitters and receivers are disclosed for communicating composite modulated signals including at least two modulated components. The transmitters include phase and envelope operators (54, 56) which generate the phase and envelope portions of the composite modulated signals separately by directly implementing the mathematical equations defining them. The phase operator (54) derives the phase portion as an audio frequency signal, and a phase modulator (58) responds to this phase signal to modulate the phase of an RF carrier signal in accordance therewith. The receivers include circuits (230, 232) for separately detecting the envelope and phase portions of the composite modulated signal. The phase signal is directed through a trigonometric operator such as a cosine (234), sine (236), or tangent (258) operator, and the output of this operator is multiplied by the envelope signal in an analog multiplier (238, 240) to recover a selected component of the modulated signal. The signals modulated onto the composite modulated signal are therefore asynchronously recovered so that carrier recovery circuitry such as is utilized in conventional synchronous detectors is no longer necessary.
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