8
THEORY OF OPERATION
The sensor, located in a housing in the front of the Diver Mag 1 , contains charcoal lighter fluid (ships empty from factory,
see page 13) which is rich in protons (nuclei of hydrogen atoms). The protons act like small bar magnets and align
themselves parallel to the earth’s magnetic field (like a compass). Several coils of wire are in the liquid and when a
voltage is applied to it (called POLARIZATION or POL TIME), the protons align to this stronger field. After several
seconds, the voltage is removed and the protons swing back to align to the earth’s magnetic field.
The protons “swinging back” induce small voltage pulses in the coils which are amplified and processed by the
microprocessor which is on-board. To optimize the amplifier, the amplifier is “tuned” (by a switch) for the frequency
(gammas) of the pulses in your area (see world map in shipping box). The tuning is very broad. Once the fish is tuned
it will operate over a very large area (+/- 1,500 gamma).
When the microprocessor receives the signal from the amplifier, it filters the signal and counts the pulses. The
microprocessor converts the count to gammas, and sends the results to the READOUT. The READOUT stores and
displays the count. The process is then repeated (called “cycling”). Two seconds of POL TIME (voltage applied to
sensor coils) followed by one quarter second of READ TIME (counting pulses). As long as the count remains the
same for each cycle, the READOUT would never change. To inform the operator that a new count is ready to be
displayed the READOUT “blinks off” for a very short period prior to the update. If the count changes with each cycle,
then the READOUT would change approximately every two and one quarter seconds.
The microprocessor also produces an audio output that shifts in frequency as the gamma numbers change. This shift
in frequency can be heard in the underwater earphone.
The Control Panel enables the operator to monitor and control the overall system. Functions such as adjustable cycle
times and sensitivity selection are done from the Control Panel.
DIVER MAG 1 SIMPLIFIED BLOCK DIAGRAM
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U/W
EARPHONES
MICROPROCESSOR
TUNABLE
AMPLIFIER
SENSOR
CONTROL PANEL
contains charcoal lighter fluid (ships empty from factory, see page 25)
