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Pointing Error Analysis Tool - Pointing Error Definitions PDF Print E-mail
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Pointing Error Analysis Tool
Pointing Error Definitions
Concepts from Optics
Standard Pointing Error Metrics
Computational Techniques for Evaluating the Pointing Error Metrics
Why Not Use the Peak Stability or Other Metric?
Pointing Error Analysis
Further Reading
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Pointing Error Definitions

Pointing Error is the angular rotation from the desired pointing direction to the actual pointing direction, or somewhat more loosely it is the difference between the actual pointing direction and the desired pointing direction.

Accuracy is the root-mean-square (RMS) pointing error of the line of sight (LOS) over any interval of time (window width Ta → ∞). Rotation about the LOS may also be considered. The three body axes may be considered rather than the LOS. The RMS accuracy is designated (σa2 + μ2)1/2.

Displacement (or Shift) is the average pointing error of the LOS within an interval of Td seconds. The Displacement Metric is used to compare the average pointing direction of one image with another.

Jitter is the RMS pointing error of the LOS within an interval of Tj seconds. Jitter is usually specified to limit blur or streaking of an image during the exposure time, to limit signal variation in a sensor, or to limit some other mensuration (measurement) error.

Stability is the RMS change in the LOS from one end of an interval of Ts seconds to the other end. Stability is usually specified for image registration or for data correlation from one time to another.

Windowed Stability is the RMS change in displacement from the center-of-integration time of one measurement to the center-of-integration time of another measurement, where the displacement is the average attitude within a window of width Td. The time between the center-of-integration times is designated Ts. The windowed stability metric therefore depends on both Td and Ts.