US Patent 7386074 Digital automatic gain control method and apparatus

An RF receiver which produces quadrature digitized outputs and has a gain control is coupled to a digital gain controller which converts the quadrature digitized outputs into an rms voltage, and iterates over a finite number of steps to quickly control the gain to a level sufficient to achieve subsequent digital signal processing without limitations caused by insufficient dynamic range or nonlinear saturation effects caused by insufficient signal or excessive signal at the A/D input, respectively.