Geometrics, Inc. G-824A Magnetometer Manual
13
Temperature
The G-824A is designed to operate over an ambient temperature range of -35 to +50°C.
In an enclosed region it may be necessary to providing adequate cooling by free flowing
air. If the sensor and electronics are in an unconfined region, convection cooling is
generally adequate. The cesium lamp only needs to dissipate 3 to 4 watts of heat and
when operating in cold regions providing some insulation or baffling around the sensor
will help reduce the sensor’s power consumption and provide faster warm up.
The G-824A requires a minimum warm up period of 15 minutes. In cold regions the
warm up period will be longer and, to avoid delay, we recommend that the sensor power
be left on overnight when ambient temperatures are expected to fall below -10°C.
5.0 OPERATION
The G-824A offers a high performance internal SupremaC CM-321 Larmor Counter. The
Larmor signal is not currently available for external counting. The internal counter can be
set up to sample at rates from 1 sample per second to 1000 samples per second. This makes
the system particularly useful when removing power grid noise or EM transmitter noise as
the AC fields are not aliased in the digital data. The CM-321 also includes a strong anti-
aliasing filter to remove higher frequencies from entering the bandpass of the counter.
The G-824A includes an ASCII text based configuration scheme covered in section 7.
6.0 TROUBLE SHOOTING
Operation of the G-824A is relatively simple and when trouble arises it is usually easy to
recognize and correct. Table 2 shows a troubleshooting guide provided to help in quickly
locating the probable cause of the most common system problems.
Symptom
Probable Causes
Corrective Actions
Long warm-up time
Low voltage.
Low ambient temperature.
Faulty sensor cable
connection.
Defective internal sensor or
electronic components.
Increase voltage (minimum 24 VDC at the
electronics) or repair the Coax cable.
Thermally insulate sensor housing.
Disconnect sensor from electronics and
carefully clean the pins and sockets.
Return sensor and electronics to Geometrics
for repair.
Noisy magnetic field
readings
Local field is noisy.
Locate and eliminate source of noise or
relocate sensor.
Table 2. Trouble shooting
