Digital tuning system for a varactor tuner employing feedback means for improved tuning accuracy

Claim 1

A tuning system for use in a communications receiver or the like of the type having a signal controlled tuning element, said system comprising means for storing a plurality of first digital numbers representative of respective tuning frequencies, a signal selector, a temporary memory, means for addressing said storage means, in accordance with the actuation of said signal selector, to select one of said first digital numbers and transfer same to said temporary memory, user actuatable means for altering the contents of said temporary memory to provide a fine tuning adjustment, said altering means comprising an actuation member, said actuation member being rotatable, to alter the contents of said temporary memory, and displaceable to cause the contents of said temporary memory to be written into said storage means at said addressed location, means for sensing the frequency at which said element is tuned, means for converting said sensed frequency into a second digital number, means for comparing the contents of said temporary memory and said second digital number for generating a signal representative of the difference therebetween, and means, operably connected to said comparing means, for generating a tuning signal in accordance with said difference signal, said tuning signal being applied to said element to control same.