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Texas Instruments Gorp.Dallas, TX AN OPTICAL MOVING TARGET indicator (MTI) where two CCD area arrays are used to obtain real time target motion information' will be described in this paper.Operation of the MTI is as follows: An optical input scene is first imaged on a CCD area array sensor; after a suitable integration time the optically generated pattern (frameA) is shifted from the imager into a CCD analog memory. Figure 1 shows a simplified diagram of the MTl system Configuration. The CCD analog memory is identical in size to the CCD imager and stores frame A, while a subsequent pattern (frame B) is imaged onto the CCD sensor. After a suitable integration time, frame B is transferred from the CCD sensor into the CCD analog memory; at the same time frame A is transferred out of the analog memory. Data are obtained at the output of both the sensor and the memory and a resolution element by resolution element comparison (difference) is made between frame A and frame B. If there is no change in the scene between frame A and frame R no output will result. If motion has occurred (a moving target) a difference signal will result.Just as the optical input scene imaged on the CCD sensor may be displayed on a CRT, this difference signal may also be displayed.The ciiffercncc signal is used to modulate the Z axis of a CRT and the X and Y p&:ion of the diffcEnce signal corresponds to the spatial location of the difference signal. A useful feature of this signal is the presence of both a black and white (negative and positive) signal which indicates the trailing and leading edges of a moving target. The positive and negative signals can be analyzed to readily define target velocity. and implementation details have been presented3. This paper will report on the operation of a CCD MTI.The CCD MTI used two 16 K element (160 x 100) CCD area arrays. The CCD arrays were three-phase, double-level metalization (Al-A1203-A1), buried channel, N-channel devices with 0.9 x 0.9 mil elements. One of the arrays was thinned and backside illuminated to operate as a visible sensor. The broadband responsivity of thc sensor was 90 mA/W t o a 2854 K source. The CTE of the devices used was 0.9995 at 1 MHz and the dark current was 18 nA/cm2 at The concept of a CCD MTI has been previously discussed'-3 Contract F33615-74-C-1054. room temperature. The devices contained on-chip amplifiers, which include both a standard prccharge amplifier and a sample and hold amplifier. Figure 1 shows a simplified diagram of the MTI system configuration. Not shown in the diagram are the clocking electronics and power supplies. The CCD arrays were driven synchronously, but were operated from independent power supplies to optimize the pcrformancc: of each device. Arnplificrs AI and A3 are differential amplifiers and serve to help eliminate clock feedthrough from the differential output of the CCD. They also serve as impedance buffers between the CCD and the system. Amplifier A2 is used to achieve the gain in signal level and also to set the de level of the input signa...

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