Tuning apparatus

Abstract

In a tuning apparatus for a broadcast receiver having a voltage controlled variable frequency oscillator for generating a local frequency signal corresponding to a selected broadcasting station, and being provided with a phase locked loop including a reference signal oscillator, a variable frequency divider which receives the local frequency signal, usually through a prescaler, for further dividing the local frequency signal with a variable dividing ratio, and a frequency and phase comparator for comparing outputs of the reference signal oscillator and the variable frequency divider, respectively, and producing a corresponding control voltage which is applied through a low pass filter to the voltage controlled oscillator for determining the local frequency signal in dependence on the dividing ratio of the variable frequency divider; a dial member is provided with a scale calibrated to represent broadcast frequencies over a predetermined frequency band and cooperating with an indicator movable along the scale for indicating the broadcast frequency to which the tuning apparatus is tuned, a series of digitally coded indicia, for example, in the form of holes in the dial member, are provided to respectively correspond to a plurality of broadcasting stations which are adapted to be selectively received by the broadcast receiver, such digitally coded indicia being spaced apart in correspondence with the spacing of the broadcast frequencies of the respective stations along the scale, and an optical or other pickup is movable relative to the series of digitally coded indicia in the direction along such series and in synchronism with the movement of the indicator along the scale for selectively reading the digitally coded indicia and correspondingly determining the dividing ratio of the variable frequency divider in accordance with the digitally coded indicia selectively read by the pickup.