Antenna switching device

Abstract

Abstract PURPOSE:To obtain a picture which scarcely causes flicker by switching an antenna into a horizontal flyback time only when the level of a horizontal synchronizing signal in a composite video signal in each horizontal flyback time is lowered from the level of the previous time by a prescribed number of times. CONSTITUTION:In case a gate circuit is turned on by some horizontal synchronizing signal, a composite video signal 1 is supplied to a peak holding circuit 6 through the circuit 2. The circuit 6 holds a peak voltage of a horizontal synchronizing signal in the signal 1. A comparing circuit 12 compares the peak voltage 10 of the circuit 6 with the peak voltage 11 of the previous horizontal synchronizing signal from a peak holding ciruict 7, and outputs ''1'' and ''0'' at the time of the voltage 11 > the voltage 10, and at the time of the voltage 11 <= the voltage 10, respectively. When the output of the circuit 11 is ''1'', the number of times of ''1'' level of the circuit 12 is counted by setting a counting circuit 18, and when the count value reaches a prescribed value continuously, the antenna is switched to other antenna in the horizontal flyback time through an antenna switching circuit 20. When the output of the circuit 12 is ''0'' level, the reception by the antenna which is being used at present is continued.

Inventors

• 👤 Takaharu Fukuyama
• 👤 福山　敬治

Bibliographic Details