BLE Beacon EKF Position Tracker

Mobile apps that can't see GPS indoors — wayfinding, asset tracking, proximity marketing — fall back on Bluetooth Low Energy beacons and the phone's own RSSI readings. This top-down simulator places a phone in a room ringed by fixed BLE beacons, converts each beacon's noisy signal strength into an estimated range using the real log-distance path-loss model, and — instead of re-solving a fresh least-squares fix every frame — runs a genuine Extended Kalman Filter over a constant-velocity motion model to track the phone's position through that noise, drawing both the raw per-beacon trilateration circles and the filter's own covariance-derived uncertainty ellipse live. Tune the path-loss exponent and RSSI noise to change how corrupted the raw ranges are, adjust the filter's motion trust to trade lag against smoothness, and toggle individual beacons to watch the uncertainty ellipse swell as the geometry degrades.