| 摘要 |
An apparatus and method for determining aircraft position and velocity is disclosed. The system includes two CCD sensors which take overlapping front and back radiant energy images of front and back overlapping areas of the earth's surface. A signal processing unit digitizers and deblurs the data that comprise each image. The overlapping first and second front images are then processed to determine the longitudinal and lateral relative image position shifts that produce the maximum degree of correlation between them. The signal processing unit then compares the first and second back overlapping images to find the longitudinal and lateral relative image position shifts necessary to maximize the degree of correlation between those two images. Various correlation techniques, including classical correlation, differencing correlation, zero-mean correction, normalization, windowing, and parallel processing are disclosed for determining the relative image position shift signals between the two overlapping images. The front longitudinal relative image position shift signal, the front lateral relative image position shift signal, the back longitudinal relative image position shift signal and the back lateral relative image position shift signal are then corrected by an altitude factor to respectively produce a front longitudinal ground distance signal, a front lateral ground distance signal, a back longitudinal ground distance signal, and a back lateral ground distance signal. These ground distance signals can be divided by the time delay between forming the first and second images to produce longitudinal and lateral ground velocity signals. The longitudinal and lateral ground distance signals can also be processed to produce other navigational measurements, such as the yaw, rotation, roll and ground track of the aircraft. The ground distance data and navigational measurements may be error checked against independent data and output to various displays.
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