Accurate target detection system
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 pr...
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| Main Authors | , , , , |
|---|---|
| Format | Patent |
| Language | English |
| Published |
04.07.2002
|
| Online Access | Get full text |
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| Summary: | 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
). The third circuit (
30, 32, 34, 38, 42, 44, 52
) further includes a subtractor (
30
) for subtracting background from the calibrated electrical signals and providing background subtracted signals in response thereto. The signal enhancement circuit (
34, 42
) includes a frame integrator circuit for adding frames of image data (
34
), each frame containing data corresponding to the background subtracted signals and providing summed frames in response thereto. The third circuit (
30, 32, 34, 38, 42, 44, 52
) includes a first threshold circuit (
44
) for comparing the filtered signal to a first threshold and a second threshold and providing a threshold exceedance signal if the filtered signal is between the first threshold and the second threshold. |
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