Automatic Chennel Indicating System with Saw Device

Today television receivers have reached a stage where electronic tuners are widely used in the place of mechanical ones. Basically two types of the digital tuning system are existing. One is voltage synthesizing utilizing a digital to analogue converter (D-A converter) and a semiconductor memory device. The other is frequency synthesizing utilizing a 1 GHz prescaler. We have already successfully developed a tuner addressing system based on the former type.(1) This tuning system is featured with one touch tuning and one touch automatic search preset and contributed to the improvement of easy operation and reliability. However, this tuning system can not indicate channel numbers automatically because it indirectly controls the local oscillator frequency by means of the tuning voltage control.