Abstract: A system for determining the angular position of a rotating element such as an engine crankshaft. An encoder wheel is divided into a plurality of equal-angle segments, each comprising a peripheral tooth extending radially over a central angle representing an angular percentage of each segment. The total angle in each segment is a tooth dwell angle and a gap dwell angle. The ratio of the tooth dwell angle to the total segment angle is the duty cycle. A prime segment is given a first tooth dwell angle. Each segment has a unique tooth dwell angle. As the wheel rotates, a sensor begins timing at a first tooth rise and determines the time to the first tooth fall and the time to the second tooth rise. Since each duty cycle is unique, for a wheel having 45 degree segments the system can determine the segment being interrogated within 90 rotational degrees.

Abstract: A method for reducing computational time for calculating a noise-filtered average approximation of a throttle position in an automotive environment. During controller initialization, an initial average value for N samples is established by conventional averaging. The sum obtained is retained for future use as a previously-retained sum. When an updated average value is required, the oldest sample value and the last output calculation are both subtracted from the previously-retained sum, and the newest sample value is added twice to the previously-retained sum, as well as being stored in sequence in the buffer. The new sum is then divided by the number of sample values to obtain a new noise filtered average approximation of throttle position, which again is retained for use in the next update. The new output value obtained by the throttle position sensor is weighed more heavily to decrease the deviation from the average approximation of throttle position.