Cushman, Darby & Cushman
Electronic digital channel-selecting apparatus
 An electronic digital channel-selecting apparatus wherein a digital signal corresponding to a selected television channel is read out of a digital memory to be converted into an analog tuning voltage by a digital-analog converter; and the analog tuning voltage is applied to a voltage-controlled tuner which in turn is made to tune with the selected television channel. An AFT circuit is coupled to the tuner to detect its tuning condition. When the tuner does not accurately tune with the selected television channel, AFT clock pulses are supplied to an AFT counter to correct the analog tuning voltage depending on varying count numbers in the AFT counter. A clock changer is provided to switch AFT clock pulses having different frequencies such that the AFT clock pulses are successively applied to the AFT counter in the decreasing order of their frequencies during the AFT control. 
Tokyo Shibaura Denki Kabushiki Kaisha
H H
H03J H03J
inventional inventional
Masahiro
Fujita