Method and apparatus for calibration of electronic delay detonation circuits

摘要

In the field of blasting, it is often desirable to ignite explosives at various relative times. Such delayed ignition can have advantages in better break up of rock and reduced ground vibration. A principle problem in using the time delay technique is the accuracy rate of a local oscillator which measures the delay time for each of the delay circuits. In the described system, a calibration interval, independent of any delay time, is transmitted from a control unit concurrently to each of the delay circuits wherein each delay circuit counts the output of its local oscillator during the calibration interval. This local oscillator output is then compared to a predetermined reference count, either at the delay circuit or at the control unit, and a correction factor is established. This correction factor is then applied to a delay count for the individual delay circuit. The delay count is modified to produce a corrected delay count that is utilized individually within the delay circuits to count the output of the corresponding local oscillator for determining the delay time until ignition. This technique utilizes the precise oscillator at the control unit to substantially eliminate the delay errors due to the less precise oscillators within the delay circuits.