Television tuning method and apparatus for tuning employing slope factor

Abstract

A tuning system for a television receiver includes fine tune memories and tuning information memories having reference channel nominal tuning information for each frequency band and nominal tuning information for each channel. Accumulator means subtract the nominal tuning information for a selected channel from the nominal tuning information for an adjacent channel to derive a slope factor for the channel. The slope factor is used to equalize an auxiliary tuning voltage source. Control logic, including channel number counters and latches and state counters, is coupled to the accumulator means, tuning information memories and the fine tune memories. The memories' and accumulator means' outputs are coupled to a corresponding plurality of comparators which are also coupled to counters for deriving pulse-width modulated (PWM) signals corresponding to tuning information in the accumulator means and memories. The PWM signals are supplied to a tuning voltage generator where they are combined to produce the final tuning voltage for the tuner. The final tuning voltage consists of the nominal tuning voltage combined with the product of the fine tune voltage and the derived slope factor.