A Microcomputer Controlled Frequency Synthesizer for TV

This microcomputer controlled frequency synthesizer is a unique electronic television tuning system. It is a frequency synthesizer that always insures crystal stability by forcing the local oscillator in the tuner to assume the same stability as a fixed frequency crystal reference oscillator. Also, microcomputer controlled tuning provides many desireable features. The microcomputer controlled signal seek will only allow the system to stop on channels that are active. It can automatically adjust for MATV frequency offsets up to ±2MHz. There never is any programming either by the user or in the factory because the system automatically seeks to the channels that are active in its present location. There is a threshold control that allows the user to skip weak signals if he wishes. Manual fine tuning is available to increase the signal-to-noise ratio for fringe area reception or as a means of minimizing disturbing signals. Finally, the direct access channel entry is arranged to clear itself if the user is interrupted in the middle of a command.