Energy Stealth Evaluation of Radar Systems with a Space–Time Modulated Probing Signal

Introduction. Increased attention is currently paid to the issues of stealth operation of various radar systems. The article considers the possibility of increasing the energy stealth of a radar system with a complex quasi-continuous signal due to additional spatial modulation of the probing signal in the radiation mode and the use of MIMO technology when receiving and processing reflected signals.Aim. Research and comparative analysis of the energy stealth of a radar system with a space–time modulated probing signal with ternary amplitude–phase modulation based on a pseudo-random sequence of maximum length.Materials and methods. The analysis of energy stealth is based on the theory of signals concerning the issues of formation and processing of complex modulated phase–code signals with a large base. A quasi-continuous ternary signal based on a pseudo-random sequence of maximum length and a regular pulse sequence providing decoupling of reception and transmission when using a single transceiver phased array was selected as a research object. A similar radar system with the same probing signal and identical N-element phased array without additional spatial modulation was used as a reference. In order to eliminate energy losses during reception and processing of reflected signals in the radar system with additional spatial modulation, MIMO technology was used.Results. Quantitative estimates of the gain in the signal level accumulated in the integrating filters of the power receiver for different accumulation time durations commensurate with the period or time of coherent processing of the radar probing signal were obtained. The cases of known and unknown carrier frequencies of the radar signal on the side of the power receiver were analyzed. In addition, the effect of the deviation of the phased array pattern from the direction to the carrier of the power receiver was analyzed. The advantage of the proposed method of spatial modulation of a signal based on a pseudo-random sequence with the property of an additive cyclic shift consists in the absence of transformation of the uncertainty function, which ensures the preservation of its correlation properties.Conclusion. The obtained theoretical and simulation results indicate an improved stealth of radar operation due to additional spatial modulation of the probing signal. The use of MIMO technology allowed energy losses during the reception and processing of reflected signals in the radar receiver to be eliminated.