AN INSTANTANEOUSLY-RESPONDING EXPANSION AMPLIFIER: A METHOD AND DEVICE FOR SIGNAL ENHANCEMENT IN NOISY COMMUNICATION SYSTEMS
ELECTRONIC SYSTEMS DIV HANSCOM AFB MA
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A variable-gain amplifier having instantaneous responsetime has been designed, constructed and tested, to enable recovery of a usable audiofrequency signal from noisy analog and digital systems. For 1-dB increments in signal level at or above -40 dBm, this device will provide increments on the order of 5 dB, over the frequency-range 50 to 10,000 cps. The rise and decay envelope is apparently symmetrical, with slopes approximating one millisecond. This report discusses design features, including a modification for analog speech signals, and gives detailed results of laboratory and field tests.