| 释义 |
white-to-black amplitude range white-to-black amplitude range[¦wīt tə ¦blak ′am·plə‚tüd ‚rānj] (communications) In a facsimile system employing positive amplitude modulation, the ratio of signal voltage (or current) for picture white to the signal voltage (or current) for picture black at any point in the system. In a facsimile system employing negative amplitude modulation, the ratio of the signal voltage (or current) for picture black to the signal voltage (or current) for picture white; this ratio is often expressed in decibels. |