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Theory Of Operation:
All magnetic locators operate on the same basic principle; two fluxgate magnetometer sensors, securely mounted inside a rigid sensor support tube, measure the local magnetic field.

The two-magnetometer sensors are vector sensors, mounted 20” apart and each measures the average magnetic field component along their sensitive axis, i.e. the magnetic field component along the longitudinal axis of the sensor tube.

For a magnetic locator to work properly, the magnetometer sensors are aligned opposing so that the magnetic field measured by one sensor is the negative of the magnetic field measured by the other. The locator then sums the output of the two sensors. By summing the two output signals, you cancel any field common to both sensors, such as the Earth’s Magnetic Field, and leave only the differential magnetic field.

The differential magnetic field, the magnetic field detected by one sensor and not the other, is the magnetic field of interest and hopefully represents the magnetic field of your target and not the field of your pocketknife, watch or the steel arch support in your shoes. The drawing on the left shows the construction of a typical magnetic locator and the location of the two sensing elements

Field Operation
Good instrument performance goes hand-in-hand with proper operation:

When searching for survey benchmarks or underground ferrous targets, the magnetic locator should be held in the vertical or near vertical position.  In this position the instrument audio output is facing the operator and the controls are readily accessible. The picture at the top of this page shows how to hold the instrument for optimum operation.

To pinpoint your target, rotate the instrument to the vertical and use and "X" or crossing pattern.  The audio output will peak directly over your target.

All Weather Operation
The sensor housing is waterproof and the electronics water-resistant.  Moreover, the circuit design and component selection ensures proper operation whether the ambient temperature is -20^oF or 120^oF.

Unparalleled Reliability
For added strength and reliability, the electronics package is made of impact resistant ABS plastic, while the sensor tube and base plate are made of 6061-T6 aluminum, welded together. Moreover, the two sensing elements are shock-mounted on there own individual support tube, inside the yellow sensor tube.  This added sensor isolation guarantees that the sensor alignment and overall instrument performance will withstand normal physical abuse and harsh weather conditions. In addition, all electronic components have been carefully selected for long life and harsh environment operation. 

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Updated: January 2005