An accurate target detection
system. The
system includes a sensor (22) that receives electromagnetic signals and provides electrical signals in response thereto. A non-uniformity correction circuit (28, 38, 52) corrects non-uniformities in the sensor (22) based on the electrical signals and provides calibrated electrical signals in response thereto. A third circuit (30, 32, 34, 38, 42, 44, 52) determines if a
target signal is present within the calibrated electrical signals and provides a target detection
signal in response thereto. A fourth circuit (38, 40, 48) selectively activates or deactivates the non-uniformity correction circuit (28, 38, 52) based on the target detection
signal. In a specific embodiment, the sensor (22) is an array of electromagnetic energy detectors (22), each
detector providing an electrical
detector output
signal. The non-uniformity correction circuit (28, 38, and 52) includes circuit for compensating for
gain, background, and
noise non-uniformities (28, 38, and 52) in the electromagnetic energy detectors. The non-uniformity correction circuit (28, 38, and 52) includes a
detector gain term memory (28) for storing detector
gain compensation values. The detector gain compensation values are normalized by
noise estimates unique to each of the detectors. The third circuit (30, 32, 34, 38, 42, 44, and 52) includes a
signal enhancement circuit for reducing
noise (34, 42) in the calibrated electrical signals. The third circuit (30, 32, 34, 38, 42, 44, and 52) includes a
noise estimation circuit (32, 38) that estimates noise in each of the detector output signals and provides noise estimates in response thereto. The
noise estimation circuit (32, 38) further includes a noise estimator circuit (38) and a recursive background estimator (32).