Apparatus for use in seismic surveying calculates duration of explosion in real time from output of detonating circuit

摘要

Apparatus has a high voltage detonating device line connected to a detonator in a hole, a detector monitoring a signal passing from the device to the detonator to measure the intensity and voltage of a detonation circuit and a processor calculating in real time the duration of the explosion from an output of the detector Independent claims are included for the following: (a) Measuring the duration of an explosion using the above device. (b) Apparatus has sensor(s) detecting seismic waves and producing an electrical signal and a processor calculating in real time from the signals the initial arrival time of the waves. (c) Method corresponding to (b) includes digitizing and sampling the detector signals calculating the mean energy of the signal in a two separate time windows and determining when it first exceeds a threshold within a quarter of the period of the incoming wave. The second window is larger and has a higher threshold and validates the result in the first window. Once validated the stored digitized signal is filtered and broken up into different sample sizes so the time of initial arrival of the seismic wave can be accurately pinpointed. (d) Measuring the duration and depth of an explosion of a stick of dynamite at depth D in a hole as above uses sensors at the surface for detecting the different arrival times of seismic waves at the sensors at horizontal distance R from the hole. In the equations, tau is the signal propagation time to the sensor, D is estimated depth of the dynamite in the hole and there are n sensors. tau n-1/ tau n = ((D<2> + R<2> n-1)/(D<2> + R<2>n))2 and D = 1/C<2>n integral Di Preferred Features: A test signal generator is used to adjust the detonation circuit.