A rejection system for interference in TV reception caused by sporadic-E ionospheric propagation

A method to cancel interference waves by extracting them from TV signals through quadrature synchronous detection and then transforming the signals with a Hilbert transform method is introduced. The system eliminates interference waves at any frequency within the TV signal band. It is easily applied to rebroadcast stations, since it is possible to cancel interference waves at the intermediate-frequency stage. The system automatically eliminates a maximum of five interference waves. It suppresses interference waves by more than 40 dB at a desired-to-undesired signal ratio of 10 dB. The system will greatly contribute to eliminating abnormal interference waves caused by the sporadic-E layer as well as other undesired interference with TV signals.<>