The present invention relates generally to moving target indication systems, and more particularly, to moving target indication systems for use with passive optical detection systems. 
Conventional signal processing systems for use with radar systems, and the like, have employed moving target indication systems.  Typical of this type of conventional system is one which employs time delayed integration.  Time delay integration, or TDI as it is commonly referred to in the art, processes detected signals in a manner such that the signal outputs from sequentially sampled detector elements are delayed by an increasing amount so that signal energy on a plurality of detector elements may be summed at the same point in time.  As a result, the target signals from all the detectors synchronously add, while the background noise from each detector adds non-synchronously at the RMS value.  Accordingly, the signal-to-noise ratio is improved by the square root of the number of detectors. 
However, for background clutter, which is a moving noise source, the signals received from this source tend to add in the same manner as the target signals, hence, decreasing the overall signal-to-noise ratio improvement.  That is to say, the clutter seen by the detectors adds in the same way as the target signals.  Therefore, time delay integration is not optimal if the dominant noise source is moving background clutter.  Another way of looking at time delayed integration is that the integration process reduces the effect of uncorrelated noise (background noise) while having little or no effect on correlated noise (background clutter). 
Numerous systems have been devised which attempt to reduce the effects of correlated clutter sources in acquiring and tracking moving targets.  Such systems include those cited in U.S. Pat.  No.  3,723,642, issued to Peter Laakmann.  However, no system to date has been designed for use with a passive optical detection system which allows for the optimal detection of moving targets in a cluttered and white noise environment. 
Accordingly, it would be a distinct improvement in the signal processing and target detection arts to provide a system which is capable of detecting moving targets in a highly cluttered background. 
It would also be an improvement in the signal processing art to provide a moving target indication system which may be utilized with a passive optical tracking system. 
It would be a further improvement in the art to provide a system which is capable of optically tracking moving targets in situations where the signal-to-noise ratio is low.