As called for in Ref. (1) the stablized turntable (scanner) was modified to sector scan tip to 36 degrees per second with no more than 2 degrees of scan at end of each scan having an error of more than ± 3 minutes, to scan continuously in one direction at a constant rate of up to 80 degrees per second, to maintain an accuracy within ±3 minutes, and operate with a load on the table up to 150 lb. – ft2 moment of inertia. The modification consists of changing the servo drive unit from a step-by-step unit to a high speed continuous control a-c servo unit. An error integrating circuit which reduces the constant velocity error is incorporated in the servo amplifier.
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