Method and apparatus for asynchronous time measurement

Time measurement apparatus comprising:

• (a) a first clock producing a repetitive clock signal at a first frequency;
• (b) means enabled upon detection of a first signal edge for discharging to a first potential and recharging until the first following edge of said clock signal;
• (c) calibration means operative during a calibration period for addressably storing a plurality of measured voltages and a corresponding charging time developed by a charge storage means relative to a plurality of measured calibration sample events of random duration and random separation from one another;
• (d) means for addressably coupling the measured voltage developed during each measured event to said storage means to determine the magnitude of the time interval;
• and
• (e) means for displaying the determined time interval.

A method for precisely measuring time including the steps of:

• (a) producing a repetitive clock signal at a first frequency;
• (b) counting complete clock cycles from a start event to a stop event;
• (c) accumulating charge during the time from the start event to a first following edge of said clock signal and the time from the stop event to the first following edge of said clock signal and separately comparing the accumulated charges relative to a linear charge characteristic table generated using calibration measurement events of random duration and random separation from one another, the table being stored in a memory, to determine corresponding times therefor;
• and
• (d) arithmetically processing the determined times of said start and stop event intervals and said complete clock cycle interval to determine the magnitude of the entire interval.