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5.5 Data Analysis Techniques <br />The Following sec[ions define the Blasttvlate 111 data analysis techniques. The first section, ground <br />vibrations, discusses calculations applied to even[ data recorded by a transducer. The second <br />section, sound pressure, describes the microphone event data calculations. <br />5.5.1 Ground Vibrations <br />The Blastlvlate III calculates the Peak Particle Velocity, Zero Crossing Frequency, Peak <br />Acceleration, and Peak Displacement for each of the transverse, venical, and longitudinal axes. <br />The Blastfvtate III calculates Peak Vector Sum using data from all three axes. <br />a. Peak Particle Velocity (PPV) <br />Peak Particle Velocity indicates the maximum speed panicles travel resulting from an event's <br />ground vibrations. The BlastMate 111 calculates the PPV for each geophone. <br /> <br /> ~-Peak Pu!Kk VebCM1y <br />~.y.. <br />i~...,..n.~ <br /> •~.. <br />i,..o.an <br />Figure 5.9 Calculating Peak Particle <br />Vtlocin. <br />b. Zero Crossing Frequency (ZC Freq) <br />The Zero Crossing Frequency calculates the even[ waveform's frequency a[ the largest peak. <br />(1) Calculating Zero Crossing Frequency <br />To calcula[e [he Zero Crossing Frequency, we need [o determine [he period of oscillation of the <br />waveform. Convenient waveform positions for measuring period, the time for one complete cycle, <br />occur between two successive peaks, roushs, or zero crossings. The BlastMate III measures <br />between zero crossings. Frequency is the number of periods that occur in one second calculated <br />by the formula: Frequency = I/period. <br /> Peak PaniUe VebcM1y <br />~mm~ <br />~rv <br />r <br /> rme <br /> e.raea <br /> r~ Zero Cross~ny <br />Figure 5.10 Calculating the Zero Crossing <br />Frequency. <br />(2) Zero Crossing Frequency Limitation <br />The Zero Crossing Frequency calculation is limited because it assumes a single predominant <br />frequency a[ the peak. tpically represented by sinusoidal waveforms. In practice, the peak may be <br />the result of two or more major frequency components representing compound waveforms as • <br />BlastMate III Operator Manual <br />