SBIR-STTR Award

The proposed research will address issues of locating an emitter with unknown waveform, and will assess the potential for improved performance through channel multipath estimation and through the synchronized diversity effect of multiple sensors. The proposed approach embodies a new algorithm that determines the location of an emitter with enhanced accuracy by combining the data from multiple SIGINT sensors in a synchronized network. The approach generalizes AOA and TDOA, normally used in triangulation methods, and combines them into an algorithm estimating location directly. The resulting location can be distributed for digital map display over a wireless virtual private network. Sensor platforms of different capabilities and sizes are automatically combined. Sensors may include random arrays and space-time processing of varying complexity. The approach is based on a new distributed signal-combining method developed by the proposing firm for geolocation of tags. Experiments with this system for known waveforms have successfully demonstrated improved location accuracy. In Phase I the performance with unknown waveforms will be studied through analysis and simulation. Performance improvements will be investigated and compared with other techniques of comparable complexity. A prototype design will be developed for a Phase II implementation planned to be demonstrated in a JTRS-type radio.The primary application is the location and tracking of potential emitters in military operations. The proposed geolocation technique also has many law enforcement and emergency applications for locating target radios. It can be used for the location of callers using cellular handsets or wireless PDAs. In addition, the technology can be used for other emitter location and tracking problems such as locating special tags to find lost children, patients, and pets, as well as tracking parolees, cargo and vehicles.

Keywords:
EMITTER LOCATION, GEOLOCATION, MAXIMUM LIKELIHOOD, RANDOM ARRAYS, DISTRIBUTED SIGINT, JTRS, MULTIPATH MITIGATION, SPACE-TIME ADAPTIVE PROCESSIN

The Phase I effort, through analysis and continuing simulation, proved the feasibility of improving the accuracy of locating an emitter with an unknown waveform by a method that uses more of the information in the received signals than previous methods. The approach generalizes AOA and TDOA, normally used in triangulation methods, and combines them into an algorithm estimating location directly. We found a superior method of selecting parameters for times when we are limited in the amount of information that can be sent to a central processing location. We developed a software simulation program to be used for quantitative assessment in typical scenarios. The method was also shown to be capable of improved location accuracy in the presence of multipath dispersion on each receive path by utilizing the synchronized diversity effect of multiple sensors. The method can be implemented with small portable location sensors with distributed control. Based on the method validated in Phase I, a complete fieldable prototype system is proposed. The system uses an ad hoc wireless network for inter-sensor communications and the design is compatible with a transition to a JTRS-type radio. The location of emitters can be calculated by the user requesting the location and can be distributed for digital map display over the network. The prototype system will be used to demonstrate performance in controlled tests.

Keywords:
DISTRIBUTED SIGINT, EMITTER LOCATION, GEOLOCATION, MAXIMUM LIKELIHOOD, MULTIPATH MITIGATION, RANDOM ARRAYS, SIGINT, SPACE-TIME ADAPTIVE PROCESS