Analog signal channel equalization with signal-in-noise embodiment

Abstract

Apparatus for reducing (a) background noise in a signal channel, and (b) channel gain variations, useful with spectral analysis equipment. Two feed forward circuits are disclosed: one to enhance a signal in noise (deriving an estimated signal); the other for AGC (relative to a preselected level). Background noise is estimated as a bias level corresponding to a minimum signal level detected within a preselected interval, the duration of such interval corresponding to a spectral interval of interest. Such noise estimate is then subtracted from the noisy signal of interest to provide a compensatorily biased signal or estimated signal. The compensatorily biased or estimated signal is then subjected to compensatory gain control by employing the ratio of a reference level to a peak detected level occurring within the preselected time interval as a gain control signal.