MODE DECISION CONTROLLER FOR SELECTIVELY ACTUATING A CHROMINANCE BANDWITH ENHANCEMENT IN A TELEVISION RECEIVER

A mode decision controller is described for actuating a conventional chrominance bandwith enhancement scheme in a color television receiver. A video signal detected by the receiver typically includes a relatively wide band luminance element and a relatively narrow band chrominance element, each of which are processed by the enhancement scheme to develop their first derivatives for use in enhancing the bandwith of the chrominance element. Either of these derivatives may be used as an input to the mode decision controller. The selected derivative is applied to a filter for removing components therefrom which extend above a given frequency range, thereby developing a frequency-limited output signal whose time domain exceeds the time domain of the selected first derivative. A signal processor receives the frequency-limited output signal and compresses its time domain to develop a control signal whose time domain is substantially equivalent to the time domain of the selected first derivative. The control signal is then used to activate the enhancement scheme.