14 Probe Zero
Understanding the Zero Function
The purpose of “zeroing” the probe and meter is to set the meter to indicate a zero field strength when there is no measurable field strength. The Narda 8700 series survey system maintains measurement accuracy under all conditions by insuring that all probes always provide true RMS (Root Mean Squared) indications of field strength. Diode detectors, which are used in many of Narda’s electric field probes, are always operated in the square law region. Since the diodes are not operated in a saturated mode to insure accuracy in
The Model 8718B establishes the zero reference as a small positive voltage inside the meter. This zero offset allows the use of only positive voltages while handling both positive and negative zero drift. While it is difficult to distinguish between a positive zero drift and the presence of an actual field, a negative indication on the meter must be due to zero drift. This is indicated on the display by a flashing negative sign between the field strength value and the unit of measure on the second line of the display.
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Chapter 14 Probe Zero | 81 |