Dynamic control circuit for multichannel system

Abstract

This invention provides an improved circuit for dynamically controlling a predetermined characteristic of each input channel of a system having a plurality of input channels to achieve a desired characteristic profile with predetermined time variances in channel aperture size and/or focal point depth. More particularly, the invention dynamically controls the gain of each input channel to maintain a desired apodization profile. A plurality of basic time varying functions (basis functions) are generated, such functions being, for example, a constant, a ramp, a parabola an exponential or the like, and at least selected ones of the basis functions are combined by appropriately weighting the functions and adding the weighted functions to obtain a desired control signal. The control signal which has the desired dynamic gain characteristic for the given channel is then applied to control a gain-controllable amplifier for such channel. The number of combining elements may be reduced by providing such combining elements for only a selected number of spaced channels and by linearly interpolating the signals obtained from such combining elements for each pair of spaced channels to obtain control signals to control gain for channels between each pair of spaced channels. System gain may also be controled by a signal generated by combining at least selected ones of the basis functions through weighting and adding.