Intermodulation components’ evaluation during radio monitoring of satellite communication lines
Abstract
Solution of radio monitoring tasks should ensure both establishing the fact of reconfiguration (changing injection frequency of trunks, polarization type, center and boundaries of service areas, etc.), as well as defining specific values of characteristics for satellite communication lines. Besides, it is necessary to take into account possible low confidence of information about satellite communication systems published in public sources, as well as uncertainty about a number of unpublished parameters (undocumented features). The purpose of this work for radio monitoring task is to evaluate impact of intermodulation effects that occur when diagnostic and data signals pass together through nonlinear repeater, as well as to evaluate impact on parameter changes of signals relayed by satellite. Variation of intermodulation activity factor is examined depending on degree of nonlinearity of repeater's amplitude characteristic and the power ratio of data and diagnostic signals at its input based on generalized model for nonlinear component of repeater operating in single and multi-signal modes. It is made clear that signal-to-noise ratio at the receivers’ input of radio monitoring devices will go down alongside with increase of data signals’ number in the repeater’s bandwidth due to power suppression of a weak diagnostic signal by a strong diagnostic signal.
