Low-cost adaptive arrays for analysis of wireless systems

This paper describes a low-cost adaptive array system suitable for both vector channel measurements and field evaluation of array signal processing techniques. This system processes signals from four antennae with a bandwidth of 2 MHz. Low cost is achieved by sending digitised receiver output directly to the internal memory of a personal computer, as opposed to traditional architectures which use a dedicated high speed bus or interconnected DSPs. The current system acquires up to 7 seconds of data in this manner before stopping to process the data. Additional cost savings are achieved using an undersampling A/D downconverter scheme, a two stage modular downconverter which allows system operation in both VHF and L-band, and a simple passive array calibration scheme. A demonstration of the system for direction-of-arrival estimation at 220 MHz is presented. Ongoing work in developing an improved system is also presented.