Prediction of Equivalent System Temperature: A Computer Methodology

There is a global trend towards utilization of satellite communications for information services. Equivalent system temperature, Ts, is a significant parameter in quantifying the antenna system/link performance, because it represents the noise power spectral density in antenna system figures-of-merit, such as receiver gain/system temperature (G/T), and end-to-end Signal to Noise Ratio (SNR). Unfortunately, Ts is dependent on many parameters. This presents a significant problem in predicting system performance in the operational environment (indoors - the antenna sees roughly the ambient temperature, outdoors - the antenna sees many other noise sources that may vary significantly over time). An innovative computer methodology is proposed that uses a novel application of noise theory and an integration of new and existing algorithms to estimate a statistical "worst case" in the operating environment based upon a desired availability. The specific objectives of the Phase I effort are to: develop a method to measure the composite system noise fugure; develop a statistical method for predicting system ambient operating temperature; develop a method to statistically estimate equivalent antenna temperature; and select supporting computer algorithms. The technical approach is to resolve each objective by addressing the individual uncertainties and unknowns of the methodology.