A Rejection Method of Interference Caused by Sporadic-E Ionospheric Propagation by an Application of Digital Signal Processing Directly to a Modulated Television Signal

Abstract

We describe a method to mitigate interference degradation in terrestrial TV reception caused by foreign FM broadcasting waves reflected by the sporadic-E ionosphere. In this method, a modulated TV signal which has interference degradation is converted to the digital signal in IF band. It is demodulated by an othogonal digital demodulator. The interference signal is canceled using the Hilbert transform of the quadrature phase component of the signal. This article describes this method in detail and its computer simulation results. 25dB-38dB of improvement is achieved against interfered TV signals at a DUR (desired signal to undesired signal ratio) of 20dB.