| 单词 | repeater |
| 释义 | repeater A device that amplifies, reshapes, and retimes an input digital signal for retransmission. In an electrically based system, the repeater essentially guesses the binary value (1 or 0) of the attenuated incoming signal, including any accumulated noise, based on its relative voltage level and the relative time, and regenerates a stronger signal of the same value without the noise. The repeater also reshapes and retimes the signal, essentially redefining the distinct bit values and restoring the bit pace. In combination, these processes considerably enhance the signal quality, as compared to the simple amplification process performed by an amplifier. In a fiber optic transmission system (FOTS), the repeater comprises a light detector and a light source, positioned back-to-back.The detector receives an attenuated optical signal, converts it to an amplified electrical signal, reshapes and retimes it, converts it back to optical signal, and retransmits it. Such optical repeaters are characterized as being optical-electrical-optical (OEO) in nature.A repeater also may perform other signal processing functions. A satellite repeater, for example, also performs frequency translation, or frequency shifting, in order to differentiate in frequency the uplink and downlink signals, thereby to avoid their mutual interference. The spacing of repeaters is sensitive to a variety of factors, including the specifics of the transmission medium and the frequency of the carrier signal. See also amplifier, attenuation, and signal. |
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