An FDM concept for GPS adaptive array antenna system

Adaptive array antenna systems have been widely used for GPS receivers for antenna beamforming and nulling. However the conventional technique requires several analog-to-digital-converter (ADC) and digital signal processing paths to achieve high performance GPS tracks in interference rich environments. This paper describes a new technique for a digital adaptive antenna, which uses a frequency division multiplexing (FDM) receiver to distribute the GPS signals from antenna elements on different parts of the spectrum so that a single ADC can capture the entire five channels. The digital signal is the fed to five digital downconverters, providing the five pairs (I/Q) of signal for digital adaptive array processing. This technique uses less components, thereby lowering cost. The challenge is to develop a high sampling rate and high performance ADC to support the interference environment and still be suitable for GPS application.