Automatic tuning apparatus

• Main Authors: USHIJIMA; KAZUFUMI, SAKAUCHI; YOSHIAKI, WAKAMOTO; SHIGERU, SUZUKI; HAJIME
• Format: Patent
• Language: English
• Published: 15.02.1977
• Subjects: BASIC ELECTRONIC CIRCUITRY; ELECTRICITY; SELECTING RESONANT CIRCUITS; TUNING RESONANT CIRCUITS

An automatic tuning apparatus comprising a tuner having a tank circuit employing a voltage controlled variable capacitance diode as a circuit element, which diode is reverse biased with a scanning control voltage from a solid state potential memory device, which control voltage is varied under the control of a scanning voltage control circuit to scan the frequencies in the frequency band by the tuner and is set by a scan stop signal obtained from the tuner as a result of tuning of the tuner to a certain frequency, said scan stop signal being withdrawn by way of a logical product of the level detected output of the IF signal and the level detected output of the ratio detected output of the IF signal, a manual switch for starting the scanning, an automatic frequency control responsive to said level detected output of said ratio detected output for charging or discharging said potential memory device, said automatic frequency control being disabled in response to the absence of the level detected output of the IF signal, and a pseudo IF signal generating circuit responsive to turning on of the power source for providing a pseudo IF signal for a predetermined period of time, whereby the automatic frequency control is performed irrespective of a possible change in the IF signal after the power source is turned off until it is turned on again.