Detecção de sinais radar chirp por receptores MAGE digitais de banda larga

Abstract

Faced with the complex electromagnetic scenario to which Electronic Warfare (EW) systems and equipment are subjected, further aggravated by the development and improvement of Low Probability of Intercept (LPI) radars, it is progressively necessary to implement new technologies in ESM receivers. LPI radars have techniques that may involve the reduction or suppression of irradiated side lobes in time, the distribution of transmitted radiated power, intrapulse and interpulse encoding or modulation, among others. These techniques pose constant challenges to the sizing and architecture of ESM receivers. In this context, this work presents the analog ESM receivers, however, it focuses on those that use the Instantaneous Frequency Measurement (IFM) circuit in conjunction with a broadband digital receiver (DRX). This configuration of receivers appears as a good alternative for the detection of LPI radar signals. Considering that Linear Frequency Modulation (LFM) signals are widely used in LPI radars, techniques, methods and algorithms have been developed in order to detect, extract and exploit the characteristics of these signals. Therefore, this work aims to analyze the performance of different detectors in the context of EW, especially with regard to the detection of chirp signals. The detectors evaluated were: a detector based on the Short Time Fourier Transform (STFT), an envelope detector, which emulates the detection performance of an analog ESM, and a frequency-channeled energy (CED) detector. A special focus is directed to CED, whose performance has been shown to be superior to that of other alternatives in the EW context. However, the performance of the CED, especially in relation to the LFM signals, is greatly affected by the selection of some internal parameters and by the variation range of the chirp, thus lacking a methodology for the selection of its parameters and consequent optimization of its performance. This work also seeks to provide a structured analysis of the performance of the CED so that a better understanding of the complex interaction between the parameters and the input signals serves as a basis for the development of a parameter selection methodology.