An Instantaneously-Responding Expansion Amplifier: A Method and Device for Signal Enhancement in Noisy Communication Systems

摘要

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. (Author)