Coordinate converter

Electronic apparatus for transforming the coordinates of at least one vector through an input angle that is a measure of rotation of a first orthogonal coordinate system relative to a second orthogonal coordinate system about a common coordinate axis comprising:

• first means for generating a first signal representative of said vector;
• second means for generating a second signal representative of said input angle;
• third means for generating an oscillation angle control signal having a transition point wherein an incremental change in said second signal at a first predetermined value causes a discontinuity in the duration of said oscillation angle control signal;
• coordinate converter means responsive to said oscillation angle control signal for transforming the coordinates of said vector through said input angle;
• fourth means for modifying the duration of said oscillation angle control signal to shift said transition point from said first predetermined value to a second predetermined value whereby a plurality of vectors may be transformed having input angles on either side of said first predetermined value without said step function thereby reducing transformation error.

Electronic apparatus for pointing a sensor where first signals indicative of a pointing direction are successively generated in a first orthogonal coordinate system and are successively transformed to a second orthogonal coordinate system having a common coordinate axis and where said first and second coordinate systems rotate about said common coordinate axis with respect to each other defining an input angle and where said input angle is measured successively to generate second signals indicative of the angular relationship between said first and second coordinate system which may include signal fluctuations due to the motion of said coordinate systems, measurement error and noise comprising:

• first means for generating said first signals;
• second means for generating said second signals;
• third means governed by said second signals for transforming said first signals from said first coordinate system to said second coordinate system;
• said third means including a plurality of transformation modes dependent upon the value of said second signals;
• fourth means to generate a third signal to select the transformation mode dependent upon the value of said second signal during the present and last past transformation;
• whereby said second signals including said signal fluctuations are transformed by said third means utilizing one transformation mode reducing transformation error which would arise from utilizing alternate transformation modes.