An Electronic System for Measuring Pendulum Periods

An electronic system for measuring the period of freely swinging pendulums has been developed for use with the Canadian Pendulum Apparatus. Extensive testing with an electrically generated test signal suggests that the error in determining the mean period of a one-second pendulum, averaged over 1200 seconds, does not exceed 100 and may be as low as 13 ns. Further testing with actual pendulums indicates that the measured periods, for a group of 3000-second observations, have a standard deviation of 600 ns. It is believed that this increased error is due to some factor associated with the pendulums, such as the effects of microseisms, knife-edge effects, or the dimensional stability of the pendulums themselves.