Patent ID: 6897435
Filing Date: 2005-05-24
Classification: G01D,G08B,H04N

Abstract:
1. A method of calibrating an optical encoder, the encoder generating two analog quadrature signals, x, y, the method comprising: a. generating a plurality of digital samples, x b. generating a plurality calibrated samples X Gx i and Gy i being scaling coefficients, Ox i and Oy i being offset coefficients, and P i being phase coefficients; c. generating a plurality of magnitude M  M j being the complex number square root of negative one and where V d. providing initial values for the scaling coefficients, Gx e. adjusting the values of the scaling coefficients, the offset coefficients, and the phase coefficients so that Gx Gy Ox Oy P the incremental adjustments being made so that a distance between the second end of a hypothetical phasor V′ i and a circle is less than or equal to a distance between a second end of the phasor V i and the circle, the circle having a pre-determined radius and being centered on the origin, the hypothetical phasor V′ i being determined by the following equations:   V′ i =M′ i exp( jΦ′ i ).