Laserfiche WebLink
<br />a. Geophone Operation <br />Functionally a geophone sensor is a coil of wire suspended around a macnet. The macnet is free <br />to move in a field of magnetic Flue lines. By Lenzs' Lass, induced vol[a:_e is proportional to the <br />speed at which Flue lines are traversed. Induced coil vol[a_e is therefore proportional to the <br />relative velocity of the coil to the magnet. In practice. it does not matter whether the coil or the <br />magnet moves. Only the motion and speed relative to each other are importan[. <br />induced <br />voltage <br />coil <br />direction of motion of magnet <br />reiative to coil <br />magnet <br /> <br /> <br />Figure 5.6 Instantel Standard Transducer (a) and Standard <br />Transducer with Optional Levelling Plate (b). <br />re 5.5 Geophone Sensor Operation. <br />Geophone sensor specifications give a number known as the Intrinsic Voltage Sensitivity. It is the <br />coil voltage induced for a given coil versus magnet speed with uni[s of V/in/s. In seismic <br />applications. the magnet is moved by the blast energy because i[ is coupled to the panicles of the <br />surrounding terrain. The coil, because of its inertia, does not move and the resulting macnet <br />versus coil motion induces a voltage which is proportional to particle velocity. <br />b. Instantel Standard Transducer <br />Instantel offers a 2 to 300 Hz standard transducer in a round package. The transducer may be <br />installed on a floor, wall, or ceiling using a variety of installation procedures including ground <br />spikes, burying, mounting rod, or optional levelling plate with levelling feet and integrated bubble <br />level. The figure below includes an Instantel Standard Transducer (a) and a S[andard~Transducer <br />wi[h levelling plate (b). <br />e <br />Y' <br />- x r <br />t'.:~f r <br />_ ~~.~,., <br />i `.ERR y, (7 <br />]~~.~Ry;.C i <br />a b <br />5--4 BlastMate III Opera[or Manual <br />