DeepGeoTech Magnetometer User Manual

Download User Manual in PDF format

The DeepGeoTech magnetometer is used to measure the strength of the Earth's magnetic field and to search for magnetic anomalies and ferrous metal.

It is possible to save profiles to a SD card and link measurements to geographic coordinates. With a magnetometer, you can detect metal objects hidden under the ground as well as fractures in the Earth's surface (faults, caves). A magnetometer does not detect nonferrous metal.

General Information

The magnetometer is a highly sensitive device. The operator must not have any ferrous and/or magnetic objects on him (keys, a compass, a buckle, a steel plate in boots, etc.). There should be no noise for the device to run correctly. The magnetometer will not work in a building, less than 200 meters away from power lines, near large metal objects that create a strong magnetic anomaly (buildings made of reinforced concrete). All electronic devices (mobile phones, cameras and video equipment) must be turned off.

The magnetic field strength in various regions of the Earth varies from 60 to 40 thousand nanoteslas. See the map of full strength of the Earth's magnetic field in 2007.

You may also calculate estimated value of magnetic field in your region with the help of the magnetic field calculator.

Setting Up (may be not required if unit is setup for your area)

The magnetometer can operate only within a narrow range of values. For switching the ranges, use the DIP swiches on the top panel and rotating filter knob on rear panel. By default the switch is at setting 4, which corresponds to the strength of 52 000 nanotesla at the latitude of Moscow.

Dip switches (range switching).


Digital filter knob

Steps

• Using map determine the approximate strength of the magnetic field in your region
• Setup the digital filter parameters (see How to set the digital filter frequency correctly)
• Turn off unit and switch the DIP switches to 0-1-2-3 if your magnetic field strength is more then 52 000 nTl or to 5-10 if less
• On working unit, setup the analog knob on the rear panel to the same number as DIP Switch

You should control the quality of the signal using manual measurement and Lost and Volatility parameters. They should be minimal.

Important: Switch the DIP switches only on switched off unit. Switching it on a working device will break the polarization scheme. Analog filter knob on the rear panel is allowed to be rotated on a working device.

Before You Start

1. Fill up the sensor with liquid paraffin (kerosene) or isopropyl alcohol (since it is prohibited to send inflammable liquids by mail, the sensor is delivered without the active substance).
2. Charge the battery.
3. Connect the sensor to the central unit with the cable.
4. Set the measurement range if it was not done earlier (see above) .
5. Turn the device on in the AUTO mode for several minutes for thermal stabilization.
6. Put the sensor on the ground so that it does not move and orient it in the east-west direction. The value spread when the sensor is motionless must be within the last digit (for instance, 52001 nT - 52009 nT) or less.

Important: The best measurements can be taken when the case of the device is grounded (the ground screw on the rear panel). Taking into account that it is impossible to ground the case during walking, it is recommended to connect the ground wire to the operator's body or just hold the rear panel with your hand.

How To Operate the Device

Slowly carry the sensor keeping it oriented in the east-west direction. Monitor the readings on the display. Keep the same distance to the ground within 30-50 centimeters. To neutralize the influence of small metal objects, you can raise the sensor to the shoulder level.

Front Panel


LCD, functional buttons 1 and 2, navigation buttons.

Rear Panel


Measurement range switch, sensor socket, battery charging socket, on/off switch.

Getting Started

After the device is turned on, the default screen is displayed and the magnetometer is automatically tested.

If the self-test is successful, you can hear a sound signal and see the LED on the control panel.

If you insert a SD card before turning it on, it will automatically create a file with a name like M12.CSV, where the number is automatically increased for each new profile.

Main Menu

You can access the main menu from anywhere in the program by pressing the MENU button.

Manual: Manual measurements.
Auto: Search mode.
Info: Information about the device.
Main settings: Main settings.
Measure setup: Measurement settings.
GPS: GPS navigator.

Lower part of the screen:
1. Battery level. Full charge is 12 volts. It shows the full charge at 10 volts, but it is possible to work with the somewhat descreased stability of the device up to 8 volts.
2. GPS navigator icon. If it is enabled, measurement coordinates are saved to the file.
3. SD card icon. It is shown if the card is inserted and ready for operation.

Attention: Insert the card before you turn on the device. Using an SD/MMC card slows down the measurement cycle, especially if there are a lot of files on the card and the profile file being currently used is overloaded.

Measuring the Magnetic Field Strength Manually

To take a measurement, press the MEASURE button.

If there is a flash drive inserted and the navigator is on, information about the strength, coordinates and time of the measurement will be saved to the profile file.

Samples: Iterations in one measurement.
Lost: Lost interations. Sensor signal quality indicator. If the sensor is not balanced (the range is set incorrectly), if the parameters of the digital filter are specified incorrectly, if the noise level is high, the Lost value increases. If the sensor is correctly set up and functions normally, the value varies within the range of 0 to 10.
Volatility: Scale of the signal amplitude (quality of signal). The less is volatility, the better. In correctly set up sensor in the absence of interference, the volatility should be within 300-600.
Fr: Sensor signal frequency.
nTl: Magnetic field strength.

Search Mode

Measurements are taken continuously. The histogram continuously shows the strength values. You can detect a magnetic anomaly in real time by their changes. When the histogram goes above or below the dotted line, you can hear a sound signal. Due to the peculiarities of the method, the signal increases not smoothly but in jerks with rises and falls. As a rule, metal objects reduce the strength of the magnetic field and the histogram goes down when they are detected. You can judge about the size of an object by the amplitude of these oscillations.

If there is a SD card inserted and the navigator is on, information about the strength, coordinates and time of the measurement will automatically be saved to the profile file.


"Analog" theme.

BALANСE button: move the chart to the center of the screen.
UP and DOWN buttons: Sensitivity.
RIGHT and LEFT buttons: Polarization impulse length.

Service Information

Firmware version, battery voltage.

Main Settings

Theme: Visual style. Analog or digital
Sound: Sound on/off.
Light: Lit display on/off.
GPS: GPS navigator on/off. The use of the navigator slows down the measurement cycle a bit.
Dig. Filter: Use digital filter on/off

Measurement Settings

Polar: Polarization impulse length. It depends on the type of the liquid being used. For isntance, it is 1000 ms for kerosene, 3000 ms for water. The longer the impulse is, the more powerful the signal is and the more precisely it can be measured, but the interval between the measurements gets longer. It is recommended to achieve stable readings from a motionless sensor with long polarization (from 1500 ms) first and then reduce it controlling the stability of readings.
Delay: Delay between the impulse and the beginning of the measurement. Transition process supression. After a polarization impulse, complex transition processes interfering with the desired signal occur in the sensor. This parameter is set in order to filter them out. 20 ms by default.
Measure: Measurement length.
After a polarization impulse, a decaying sinusoidal signal that needs to be measured occurs in the sensor. The longer the signal is measured, the more precise it is, but: The signal length depends on the type of the liquid being used. For isntance, it is 700 ms for kerosene, 2000 ms for water. It is followed by noise. To take a precise measurement, it is necessary to capture as much as possible of the desired signal and as little as possible of the noise. It is recommeded to start at 500 ms and increase it controlling the stability of readings from the motionless sensor.
The entire length of the measurement cycle consists of POLAR + DELAY + MEASURE + coordinate detection time + time to save the data to the SD Card .
Filter f: Central frequency of the digital filter.
Filter b: Digital filter bandwidth.
Debug: Debugging mode on/off. Debugging information: the data stream from the sensor is written to the file debug.csv, the data stream from the navigator is written to the file gps.txt. Slows down the operation very much.

How to set the digital filter frequency correctly

Filter f: Switch to the manual measurement mode, measure the magnetic field strength, remember or write down the Fr value (frequency). Go to the measurement settings, enter the previously obtained value into the FILTER F parameter (central filter frequency). This parameter equals 2200 Hz for Moscow. It is enough to set the central frequency just once.

Filter b: Bandwidth - the narrower the bandwidth is, the more effective the filter cuts the noise, start from 200 Hz and reduce it controlling the Lost parameter and the stability of readings from the motionless sensor in the manual measurement mode. Do not set FILTER B to less than 50 Hz.

GPS Navigator

Geographic coordinates and time.

After you turn on the device, the duration of the cold start is about 35 seconds. The cold start may take longer depending on the conditions (cloudiness, trees). It is recommended to turn the navigator on in Main menu -> GPS first, wait for stable coordinate detection and switch to the search mode without turning the power off.

Storage and Transportation

Charge the baterry after operation. It is not permitted to store the device for a long time with the discharged baterry. Pour out the proton-rich liquid in case of mail delivery or long transportation. Change the proton-rich liquid once a year. Avoid impacts and compression, use a packaging box.

Active Substance

Proton-rich liquid is used as an active substance. We recommend kerosene or isopropyl alcohol because they have short polarization time and the acceptable electromotive force of the desired signal. You can try using other liquids and mixtures containing hydrogen at your own risk: distilled water, various alcohols, liquid paraffin, you may have to set different values for the polarization and measurement time in this case. You should avoid using agressive liquids and solvents (gasoline, acetone, etc.).

SD Card

Use drives up to 2 gigabytes inclusively. Before use, format it on the computer using the FAT format. It is not allowed to use other formats (FAT32, NTFS).

Charging the Battery

Plug the charger to the socket on the rear panel. The green LED will become lit on the charger. When the battery is fully charged, the LED will go out and the charger will be switched into the charge maintenance mode in which it can remain permanently without doing any damage to the battery.

Software

The DeepGeoTech Viewer program is used to visualize and analyze the profiles the magnetometer saves to the SD card.

Open button. Open the profile file (you can select several files).
Close button. Close the program.
Files window. Select the profile file in the list that will be displayed.
Profile window. Magnetic field strength change chart. Double-click the chart to see on the map where the measurement was taken.
Google Map window. Measurement location marked on the map.
View style list. Select the chart scale.
Map View buttons. Select the map type: regular, satellite, combined, topographic.

Package Contents

Central unit - 1 piece
Sensor - 1 peice
Sensor cable - 1 piece
Software
Charger
User manual

Warranty

The manufacturer guarantees the operation of the device and the absense of manufacturing defects. Samples of all devices are tested in the field and verified with a test protocol. The manufacturer shall fix all defects caused by the manufacturer for free within 1 year after the purchase. Contact the dealer you purchased the device from or directly the manufacturer for warranty and post warranty repair. No warranty service claims are accepted in case of any violations of the operation instructions, mechanical damages, damaged seals or any traces of unauthorized repair.