| 摘要 |
<p>A multiple-channel information translation system includes a Bragg light-sound interaction cell interposed in the path of a spatially coherent input light beam. Carrier generating means generates a plural number greater than two of electrical carriers each having a different RF frequency. The carriers are respectively amplitude modulated by information-bearing input signals to produce a like plural number of amplitude-modulated carrier signals used to drive the Bragg cell. The cell Bragg-diffracts the input beam into a corresponding plural number of primary output light beams respectively amplitude-modulated in accordance with the input signals. The carrier generating means causes the frequencies, or frequencies and relative phase, of the carriers to be such that random, signal-related spurious amplitude modulation of the primary output light beams which might otherwise result from cross-channel interference effects in the cell is suppressed. In one disclosed embodiment the carrier frequencies are selected such that the frequency differences between each carrier frequency and all others are equally spaced in the frequency domain. In a second disclosed embodiment the carriers are phase-locked in order to effect the said suppression of spurious amplitude modulation of the primary output beams.</p> |
