A virtual RSNS direction finding antenna system

Abstract

In this thesis, a performance analysis and improvement of a phase sampling interferometer antenna system based on the Robust Symmetrical Number System (RSNS) in the presence of noise is investigated. Previous works have shown that the RSNS-based DF technique can provide high bearing resolution with a minimum number of antenna elements. However, the previous experimental data showed significant deviation from the theoretical results expected due to imperfections, errors, and noise. Therefore, an additive Gaussian noise model of RSNS-based DF was established and simulated. Simulation results show that the presence of noise distorts the signal amplitudes used in the RSNS processor and causes degradation of the angle-ofarrival estimates. A performance analysis was undertaken by first introducing the quadrature modulation configuration into RSNS-based DF system, which provided a digital antenna approach for more flexibility in the signal processing. With a digital approach, variable resolution signal preprocessing can be employed, using a virtual channel concept. The virtual channel concept changes moduli values without changing the actual physical antenna element spacing. This attractive property allows the RSNS algorithm to be implemented into existing antenna arrays and only requires modifying the antenna signal processor. Computer simulation results showed that the proposed method can successfully improve the system performance and also mitigate the effects of noise.