Engine control apparatus using signal with level changing with engine operation

A program product embedded in a media accessible by a computer for controlling an engine, the program product comprising:

• an interval measuring for instructing a computer to receive an input signal input thereto and composed of a regular region and an irregular region repetitively appearing in time, the input signal having a level that regularly changes in time in a predetermined direction in the regular region thereof every amount of regular operation of the engine, the level irregularly changing in time in the predetermined direction in the irregular region thereof with an amount of irregular operation of the engine, the interval measuring means being configured to instruct a computer to sequentially measure an interval between appearance of a predetermined-directed level change in the input signal and that of a temporally next predetermined-directed level change therein;
• a multiplication clock generating means for instructing a computer to sequentially use one of the measured intervals as a reference interval and to divide, by a multiplication number, the reference interval so as to generate a multiplication clock, the multiplication clock including a train of clock pulses whose clock cycle corresponds to a division of the reference interval by the multiplication number;
• an engine control means for instructing a computer to control the engine in synchronization with the multiplication clock generated by the multiplication clock generating means;
• an irregular-region start detecting means for instructing a computer to detect that a predetermined-directed level change in the input signal is synchronized with a start of appearance of the irregular region thereof;
• an irregular-region end detecting means for instructing a computer to detect that a predetermined-directed level change in the input signal is synchronized with an end of the irregular region thereof;
• a fixing means for instructing a computer to fix the reference interval to a predetermined value when it is detected that the predetermined-directed level change in the input signal is synchronized with the start of appearance of the irregular region thereof;
• and
• a resetting means for instructing a computer to reset the reference interval from the predetermined-value to one of the measured intervals when it is detected that the predetermined-directed level change in the input signal is synchronized with the end of the irregular region thereof.