Echo Ridge works in the space of signal processing algorithms, software design, and hardware design and production. The firm's primary focus is wireless applications including communications systems, position/navigation/timing, electronic warfare and modeling/simulation/test. Technical Expertise for Echo Ridge include: Radio propagation modeling, simulation, and real-time emulation for dynamic multipath environments; Cognitive functionality for radio, navigation, radar, networking, and electronic warfare applications; Commercial wireless systems such as LTE, UMTS, GSM, CDMA 2000, WiMAX, GPS, and Assisted-GPS; In-depth knowledge of commercial wireless specifications and how they are deployed and operated worldwide; Wireless emitter geolocation systems, including system level design considerations, signal processing algorithm development and simulation, real-time software development and testing, and large-scale deployment methodologies; Time Difference of Arrival, Frequency Difference of Arrival, Angle of Arrival, interference cancellation, and position estimation algorithms; Weak signal detection, mitigation of measurement errors in cluttered RF environments, and algorithms for highly optimized signal processing; GPS-denied geolocation and navigation using RF signals of opportunity; Autonomous robotic navigation techniques such as extended Kalman filtering (EKF), Simultaneous Localization And Mapping (SLAM), fused with mechanical, inertial, and optical data from Inertial Measurement Units (IMU), optical range-finders, and odometry sensors.