Abstract
In Bangkok, Thailand, also the frequency band of 50MHz is used for television broadcasting. The viewer of TV programs dissatisfied about television ghost signals of unaccountable. The TV signals level varied in sine wave form, and was to repeat the rise and fall of the signal level several tens times. The quasi-periodic level fluctuation exceeding 2 dB was sometimes more than 10 dB. Based on the results of the observation of the quasi-periodic level fluctuation over long years, it is shown that it is related to the transit of airplane and intensity of the received signal level.
