Signal processing by adaptive antenna arrays

This article outlines the basic theory of adaptive antenna arrays. The basic elements of an adaptive antenna array such as a diagramforming device and an adaptive processor are presented. The task of the adaptive processor is to control the diagram forming device, which provides the required processing of the input observation based on the available a priori information on the signal-interference environment. When such information is insufficient, the adaptive processor must have the ability to automatically adjust to the receiving conditions. In other words, the adaptive processor must implement some adaptation algorithm based on the initial data bank and the signal processing efficiency criterion. To quantitatively evaluate the performance of adaptive antenna arrays when receiving a useful signal, one of the ways of quality indicator has been considered: the RMS value of the deviation of the useful signal from the reference.

Space-Time-Frequency Adaptive Processor for Multiple Interference Suppression in GNSS Applications

To enhance the multiple interference suppression performance of global navigation satellite system (GNSS) receivers without extra antenna elements, a space-time-frequency adaptive processor (STFAP) is investigated. Firstly, based on the analysis of the autocorrelation function of the multicomponent signal, we propose a common period estimation and data block technique to segment the received signal data into blocks. Secondly, the signal data in each block are short-time Fourier transformed into time-frequency (TF) domain, and the corresponding TF points with similar frequency characteristics are regrouped to structure space-time-frequency (STF) data matrixes. Finally, a space-time-frequency minimum output power- (STF-MOP) based weight calculation method is introduced to suppress multiple interfering signals according to their sparse characteristics in TF and space domains. Simulation results show that the proposed STFAP can effectively combat more wideband periodic frequency-modulated (WBPFM) interferences even some of them arriving from the same direction as GNSS signals without increasing the number of antenna elements.