The present invention relates in general to interval timers and particularly to a method and apparatus for calibrating such timers to reduce errors due to mismatches between separate timer input channel paths.
Two-channel interval timers typically measure the time difference between occurrence of events, represented by electrical signals, as they arrive at separate timer channel input terminals, the first arriving signal starting the timer and the second arriving signal stopping the timer. Since the signals usually originate at sources remote from the timer, a difference in the length of the path each signal must follow from the source to the timer can cause an error in the time measurement. Also, differences in the path lengths or internal switching means or other sources of delay within the timer itself, can cause additional errors in the time interval measurement.
What is needed, and would be useful, is a method and apparatus for measuring the error caused by differences in channel path lengths or other delay mechanisms between two input channels of an interval timer so that such error may be calibrated out of the time measurement.