SatisGeo PMG-2, User Manual

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3.3. Operation Principle
The measurement of the magnetic field is conducted in two steps. In the first
measuring step, the polarization current feeds the sensor and causes uniform orientation
of magnetic moments of hydrogen nuclei contained in the liquid in the sensor. The time of
polarization is automatically increased, in MANUAL and AUTO measuring modes,
according to the decreasing source voltage so that the precession signal gained from the
sensor may remain constant. In WALK measuring mode, the polarization time is fixed.
During the polarization cycle, the sensor and the low-noise amplifier are disconnected.
The first step of the measuring sequence is terminated by switching the polarization
current off.
In the second step, due to an interruption of the polarization current in the sensor,
the transient field is dumped, and then the low-noise amplifier is connected to the sensor.
The signal induced in the sensor is amplified, filtered, and shaped to suit the processing
in numeric circuits. In the sampling circuit of the microprocessor, the frequency of
attenuated oscillations of the precession motion of the hydrogen nuclei is evaluated. The
frequency is directly proportional to the measured magnetic field.
The entire measuring cycle is controlled by a microprocessor which computes the
measured magnetic field and statistical error of the measurement from the value of the
frequency of the precession. Both values are displayed and optionally stored in the data
memory.
During the second step, the amplitude of the precession signal and the time
constant of the decay are determined. The supplementary values are also stored in the
data memory.
3.4. PMG-2 Magnetometer Operating Controls
[ON / OFF] switching on and off
[ENTER] start of measurement or other selected procedures, setting validity of
modified parameters or data, storing measured data in the memory
[ESC] termination of any going-on procedure without storing data
[NEXT] next item
[0] to [9] loading digits
[ v ] scanning series of consecutive data towards higher ordinal numbers
[ ^ ] scanning series of consecutive data towards lower ordinal numbers
Table 3.1 - PMG-2 operating controls.
3.5. Main Menu
After switching the instrument on, by means of the push-button [ON/OFF], the
initial logo appears on display.
After pressing any push-button or after 3 seconds, the main menu appears.
The backlight is switched off automatically 30 seconds (default value is 30 s, other
options selectable) after the last pressing of a push-button. The backlight can be
switched off all the time to save power consumption.