An Interference Prediction Model

An Interference Prediction Model (IPM) has been developed and programmed to facilitate RFI studies at satellite tracking stations. It can be used for RFI studies in general as well, because of the great flexibility of its input. Input descriptions include the receiver location, response characteristics, topographic data, and suscepibility parameters; also, emitter location, and spectral energy distribution and characteristics. Ordinarily, a mathematical formulation is used in IPM´s to describe receiver response curves and emitter spectral energy distributions. By contrast, this IPM describes such functions to any desired degree of accuracy by linear approximations with execution time input data. This method provides both flexibility and ease of modification. Incorporated into the IPM is the capability of representing up to seven different malfunction threshold levels for different types of interference, arbitrary weighting functions for interference types, and arbitrary signal-noise ratios for adjusting malfunction levels, either singly or in groups. Three operating modes are available with this IPM: a mandatory single-emitter mode and optional multiple-emitter and intermodulation modes. Use of the single-emitter mode entails calculation of the interfering power at the receiver due to each emitter and the interference comparison. Use of the multiple-emitter mode entails summing the results of the single-emitter mode, by frequency segments, before comparison. The intermodulation mode performs calculation and comparison of the interference resulting from the ¿beating¿ of pairs of emitters.