Geometrics G-822A, Руководство по эксплуатации

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Geometrics, Inc. G-822/G-823 Magnetometer Manual
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1.0 INTRODUCTION
Congratulations on your purchase or rental of one of the finest cesium vapor
magnetometers ever produced. This manual will provide you with an understanding of
alkali vapor magnetometer technology and will give you instructions for installing the
system for airborne, land or marine use. It is not meant to be exhaustive for every case as
there are many different situations and applications in which magnetometers can be used.
Please contact the factory if you have specific questions relating to your special
application.
The Geometrics G-822A and G-823A magnetometers employ an optically pumped
Cesium-vapor atomic magnetic resonance system that functions as the frequency control
element in an oscillator circuit. The G-823A is simply a G-822A containing additional
counter circuitry that internally converts the magnetometer’s analog signal into a digital
RS−232 output. Because the G-822A is identical to the G-823A in all other respects, the
installation instructions are provided referencing the G-822A only. However they apply
to the G-823A as well. A description of the G-823A operation is presented in the last
chapter.
The frequency of the magnetometer
electrical oscillator is known as the
Larmor frequency and it varies directly
with the ambient magnetic field at the
sensor. When this frequency is
accurately measured it provides a
precise measurement of the total
magnetic field. The design of the
sensor optical package uses a split-
beam design which eliminates the need
to optimize sensor orientation to obtain
precise measurements.
As shown in Figure 1, the G-822A
magnetometer consists of two
interconnected modules: a sensor
module and sensor driver module.
The G-822A relies on counter circuitry
that is external to the sensor driver
module, that can be a Geometrics
SuperCounter, an RMS Instruments
AADC II, or other form of counting
device. Some users elect to use their
own counter circuitry with the G-822A.
In these cases Geometrics can supply an
Figure 1. G-822A Sensor and Sensor driver module