Direction finding and “smart antennas” using software radio architectures

Operational tests and demonstrations of systems based on software radios are currently being performed in the 800 MHz mobile cellular radio band. These field trials are for mobile unit geolocation systems and adaptive phased array “smart antenna” applications. The geolocation system trials are in response to the demand for high confidence geolocation of mobile units for enhanced emergency 911 service and for use in the US Department of Transportation´s Intelligent Vehicle Highway System (NHS) initiative. The smart antenna array application addresses the cellular service providers´ need for more user channel capacity and/or geographic coverage from existing base station installations. Software radio architectures were selected because of their ability to provide superior performance at low life cycle cost. These systems use 4 to 8 wideband coherent channels and fully characterize the arriving RF energy to either geolocate the emitter or to maximize the carrier-to-interference ratio