Magnetometer-Gradiometer MG400 User Manual

Magnetometer-Gradiometer MG400 User Manual

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Table of contents

1. Gradiometer design and principles of operation

1.2 Parts included

1.3 Technical Specifications of MG-400

1.4 Assembly of gradiometer

1.5 Batteries and charging

1.6 Technical support

2. Operating instructions and tuning the device

2.1 Controls.

2.2 Menu

2.3 Tuning MG-400

2.3.1 Balancing

2.3.2 Alignment

2.3.3 Compensating temperature drift

2.3.4 Saving tuning parameters

2.4 Express map

2.5 Site Layout setup

2.6 Memory. Transfer of data to computer

3. Field work

3.1 Detailed area survey

3.1.1 Topographical work

3.1.2 Magnetic logging

3.1.3 Express Map

3.1.4 Custom Problems and Solutions

3.2 Scanning

4.  Software Radius

4.1 Connecting gradiometer to computer

4.2 Working with software

4.2.1 Application “term.exe”

4.2.2 Application “mag.exe”

4.2.3 Application “level.exe”

4.2.4 Application “karta.exe”

Warranty

 

 

1 Gradiometer design and principles of operation

Picture 1. Gradiometer MG-400

Picture 1. Gradiometer MG-400

Gradiometer MG-400 consists of two main parts:

Horizontal bar with attached electronic block, battery compartment, and handle.

Vertical bar with 2 sensors inside

Connecting cable is permanently attached to the horizontal bar and connects to the vertical bar through a plug. The handle has two duplicated “Start” buttons.

Electronic block (Picture 4) contains buttons for controlling the device. Battery compartment has a plug – RS232 for transferring data to computer, ON/OFF switch, and a plug for battery charger.

Gradiometer works by measuring the difference of magnetic field between two points in space. The results are displayed either as a graph when used in the Scan mode or as a gradient map when used in theTopography mode.

Magnetic field sensors are located at the opposite ends of the bar. The sensors must be parallel and have identical sensitivity. However in reality sensors are not entirely identical in sensitivity and change their qualities with changes in surrounding temperature. This is why gradiometers need to be tuned periodically.

There are two basic types of tuning: balancing and alignment. All tuning is done electronically.

Balancing evens out sensitivity of the sensors whereas alignment sets them parallel to each other. If the device is not appropriately balanced, it will show amplified changes during small tilts while moving. If the device is not aligned, it will react to turns relative to cardinal directions.

The process of tuning gradiometer is described in detail in part 2.3 “Tuning MG-400”.

1.2 Parts included

Picture 2 MG-400 in transportation case

Picture 2 MG-400 in transportation case

Parts included:

Electronic module attached to the horizontal bar

Battery compartment with rechargeable batteries on the opposite end of the horizontal bar

Bar with sensors

Power source for recharging batteries

CD with drivers, software, and user manual

Com-cable for downloading data to computer

Carrying case

1.3 Technical Specifications of MG-400

Distance between sensors – 900mm

Working range +/-25,000 nT

Digital display resolution 0.1 nT

Data storage resolution 0.1 nT

Frequency of measurements:

In scan mode: 2 times per second, 5 times per second, 10 times per second

In area survey mode: 4 times per meter irrespective of speed

Display refresh rate – 10 times per second

Memory to store 125,000 measurements

Electric consumption: without backlight 110 mA, with max backlight 150 mA

Data storage time period – 10 years at 25 C

Grid (width of the square) 10, 20, 40, 80 meters

Power source 4 rechargeable D type batteries with 10,000 mAh capacity

Battery life – 90 hours (60 hours with Max display backlight)

Operational temperature range from -20C to +50C

Weight (including batteries) – 5.3 kg

Power source for recharging batteries: output 800mA at 12V DC. Can be used with appropriate car adaptor.

Full recharge time 10-12 hours

All specifications can be changed without notice

1.4 Assembly of gradiometer

Insert bar with sensors into the holders on the horizontal bar. It should be inserted from below so that the plug on the bar is below holders and facing electronic block. Adjust its position inside holders in a way that leaves the bottom of the sensor bar approx. 20-25 centimeters above ground during movement. Tighten the knobs on the holders without excessive force but tight enough for the bar not to slide during movement.

Connect the cable coming out of the horizontal bar with sensor bar plug. The device is ready for operation.

1.5 Batteries and charging

Picture 3.Gradiometer MG-400 uses 4 regular rechargeable D type batteries with 10,000 mAh capacity.

Picture 3.Gradiometer MG-400 uses 4 regular rechargeable D type batteries with 10,000 mAh capacity.

 

The power source included with the device converts 220V/110V AC and 50 Hz into 12V DC at 800 mA. The device can also be charged with appropriate automobile charger.

Insert the power source into the plug on the battery compartment and connect it to the 220V outlet. Irrespective of whether gradiometer is turned on or off, display will become lit up showing MENU, and battery symbol in the top right corner will start blinking. Full battery recharge time is 10-12 hours. After recharging is complete the device will stop it automatically and make a beeping sound every 3 minutes. One full charge of batteries will allow 90 hours of work at 20C. (if necessary rechargeable batteries can be replaced with regular D type batteries)

When replacing batteries the data inside the device is safe.

1.6 Technical support

Full technical support is provided free by phone or email. If you have a question please address this manual first. It contains a lot of help and advice. If you cannot find answer to your question, please contact us by phone or email provided at www.magnotracker.com
When contacting the support please have the following information available:

Your name, company, your contact information and serial number of your device

Detailed information about your issue. Please be as specific as possible.

Actions you took to fix the issue.

2. Operating instructions and tuning the device

2.1 Controls.

Picture 4 Front panel of the electronic block

Picture 4 Front panel of the electronic block

 

Front panel of electronic block has 4 buttons with arrows and central “Enter” button. They allow to navigate through MENU which is entered through MENU button.

M button stops the movement of the graph in SCAN mode

N button drops readings to zero during tuning of the device

The handle of the device has two duplicated “START” buttons which are used in the following situations:

– Drop readings to “0” in SCAN mode

– To enter parameters before starting area survey

– In “Topography” mode to start and stop logging

– “ENTER” to set gradient during balancing and alignment tuning

2.2 Menu

SETTINGS SCAN TOPOGR
MAP PLAN MEMORY

 

Above the table – temperature inside the device, date, clock – hours, minutes, seconds.

Controller cursor is set on SETTINGS cell – press ENTER to enter SETTINGS submenu

Enter SCAN to switch to Scan Mode

Enter TOPOGR to enter “TOPOGRAPHY” mode with topographic logging using cables

Enter MAP to view gradient field on the completed area

Enter PLANto divide surveyed area into grids

Enter MEMORY to transfer data to computer or erase memory

 

After entering SETTINGS the following submenu opens:

BALANCE TMP DRFT DEFAULTS
ALIGNMNT SET “0”
SOUND CONTRAST
TIME BACKLIGHT

 

By using controls and ENTER buttons the following functions are activated in this submenu:

BALANCE – Balancing tuning of the device

ALIGNMENT – Alignment tuning of the device

TMP DRFT – sets temperature drift compensation

ZIGZAG (PARALLEL) – sets the mode in which surveyed area is traversed – zigzag or parallel routes

SET “0” – Allows to reset alignment and balancing tunings to 0 level before tuning procedure or save current tuning parameters as default.

SOUND – sets sound volumeand threshold levels

CONTRAST – sets display contrast

DEFAULTS – reverts to manufacturer’s settings

TIME – sets time

BACKLIGHT – sets brightness of backlight

 

2.3 Tuning MG-400

Magnetometer needs to be tuned to account for small tilts and turns that occur during movement. Balancing compensates tilts and alignment compensates turns. For this reason when tuning gradiometer, move it to the same extent as you expect it to be moved during work (approximately 10-15 degrees). Hold gradiometer oriented to the North while performing this operation.

Before tuning alignment, balance, and TEMPERATUREDRIFT settings, the device electronics must be “warmed up” for at least 20-30 minutes. Leave the device turned on in SCAN mode so the sensors are also turned on.

After device has been warmed up, find a square area (using device in SCAN mode) approximately 1.5 by 1.5 meters with gradient change no more than 1-2 nT.We are going to call this area Checkpoint. Using a compass find the direction of NORTH, SOUTH, EAST, and WEST and mark them. This area will be referred to as CHECKPOINT.

Gradiometer tuning is usually performed in the following order: Balancing – Alignment – Balancing. If needed the tuning cycle can be repeated. In most cases one balancing is enough, however during first use, after device hasn’t been used for a long time or during severe temperature change a full cycle of tunings might be needed.

2.3.1 Balancing

Move to MENU option “SET ‘0’”, set electronic “0” by pressing “ENTER”. This action is only needed during the first balancing of the cycle (balancing-alignment-balancing). During second balancing in the cycle or when performing only one balancing, setting electronic “0” is not needed.

Stand in the middle of the Checkpoint, face NORTH, making sure device is also aligned to the North and sensor bar is vertical to the ground.

Choose MENU option “BALANCE” and press “ENTER”. After a couple seconds the display will read: “TILT NORTH”

Tilt the device in the direction of North (the top sensor of the barshould tilt towards North) several degrees like it tilts during normal walking along the route and press “START” on the handle. Bring the device to the initial (vertical) position. The display will read “TILT SOUTH”.

Tilt the device to the South and press “START” again. Repeat actions 4 and 5 following commands on display until you hear sound and display reads “BALANCING COMPLETED”. Usually it takes 3-5 cycles and takes no longer than a minute or two.

Number 16 that shows on display right after switching to “BALANCE” mode is the size of increment that device uses to balance the sensors. Size of the increment can be increased using horizontal arrows of the keyboard up to 32, if device is strongly out of balance and it is taking too long to balance it. Usually the increment can be decreased for more precise balancing in the following sequence: 16; 4; 2.

Several seconds after displaying “BALANCING COMPLETED” the display will show a graph. By looking at the graph and swaying the device back and forth and left and right you can assess the quality of the achieved tuning. If the balancing is preliminary (done before alignment) you shouldn’t aim for best result since during alignment tuning some disbalance occurs. This disbalance will be corrected with final balancing (after alignment). Final balancing should be done more thoroughly since quality of work with device will depend on it. If necessary the whole cycle should be repeated.

During balancing procedure display might show EEEE or “Cannot calculate” which means that compensation is maxed out. Continue balancing procedure and processor will resolve this issue itself.

2.3.2 Alignment

Alignment can be performed in a simplified version when you are logging an area. Full alignment might be needed in some cases during extreme temperature changes or when device was struck against something.

Simplified alignment

Orient gradiometer to the North. Choose alignment option in menu. Turn device 3-5 degrees to the East, press Start button, return to initial position. Then turn device 3-5 degrees to the West and press Start again. (Display might give commands to turn device in other directions but they can be ignored. These commands need to be followed only during full alignment procedure). Repeat this procedure several times until the difference between extreme positions is down to 1-2 nT. Alignment is completed.

Check balancing and if necessary tune it again.

Full alignment procedure:

Device can remain in “BALANCE” mode.

  1. Standing in the middle of the checkpoint first turnNorth, then South. Remember the difference between readings.
  2. Turn West, then East. Compare the difference between North-South directions to the difference between East-West directions. If the difference in any pair of directions is bigger than 3-5 nT (for example facing North device reads +12 nT, South +25 nT (difference 13 nT); to the East -2 nT, West +1 nT (difference 3 nT), start alignment tuning with that pair of directions. The difference between PAIRS of directions can be bigger, however ideally there shouldn’t be big difference between opposite directions (North and South or East and West).
  3. Through MENU move to ALIGNMENT mode. As was explained above, start with pair of directions with bigger difference in readings. Switching between pairs of directions – North-South and East-West is done by pressing “ENTER”. For example when starting with North-South direction, the display will read: “Direction North”Dirnorthection NORTH
  4. Turn to face North, press “START” on the handle;
  5. After “Direction SOUTH” appears on display, turn South, press “START”;
  6. Notice the difference between directions by observing readings on display again.
    Alignment tuning increment can be adjusted with horizontal arrows as with balancing procedure.
    Repeat actions 4-6 several times until difference between opposite directions is 1-3 nT. Then by pressing “ENTER” button move to tuning the directions pair East and West and repeat the same actions in directions East and West. After completing press “ENTER” and check to make sure the readings in directions North-South haven’t misaligned. If needed repeat actions 4-6.

After completing alignment, check and if needed repeat balancing. If you made a mistake by turning in the wrong direction and pressing “START” and device stopped tuning move to the “DEFAULTS” option of the MENU, revert to manufacturer’s default settings and begin tuning procedure again.

2.3.3 Compensating temperature drift

Temperature drift occurs during change in surrounding temperature and resulting change in temperature of sensors and device. It will be seen as constant drift of device readings in one direction. This might affect quality of the final gradient maps.

Gradiometer MG400 has digital temperature drift compensation. Level of compensation can be changed manually or automatically between 0 and 10.
Temperature drift compensation should be set after device has been sufficiently warmed up (20-30 min in Scan mode).

Choose menu option “Settings”. Choose option “TMP DRFT”. Countdown from 5 to 0 accompanied by a sound will begin. During this period put device down so it doesn’t move. It doesn’t matter how it is oriented in space. Next countdown will begin from 30 to 0 seconds also accompanied by a sound. During this period processor will determine temperature drift and choose appropriate level of compensation. Keep device immobile during the whole 30-second period. By observing the moving graph on display make sure the drift has been compensated. You can begin logging.

During area logging it is recommended to check and correct temperature drift periodically. Especially during sharp surrounding temperature changes. It can be performed during periodic stops at checkpoint.

2.3.4 Saving tuning parameters

All completed tuning settings – balancing, alignment, and temperature drift are saved automatically. Choose SET “0” option of the MENU. You will see 2 options:

Set balance and alignment to 0

Save balance and alignment as default

By pressing “YES” to “Save balance and alignment as default” you can create your own “default settings”.

Other magnetometer settings (zigzag/parallel routes, sound, backlight, contrast, Z, time, defaults, help) are adjusted by simply choosing the appropriate menu option.

2.4 Express map

Express map allows user to see magnetic field of the area, locate objects, and if necessary make adjustments to field work – change technology, size, and location of the surveyed areas. This function spares operator the need to download data to computer. In “Topogr” mode, graphic display (128×240 pixels) shows express map of the surveyed grid in real time. Display allows to see 17 levels of gray scale within 30 adjustable ranges of the field gradient. Operator chooses the range of the gradient he wishes to see from 5 to 1250 nT.

Express map of the field gradient on MG-400 display

Picture 5. Express map of the finished area. Information on the top of the screen from left to right: SQ-01 – SQUARE #1; RT-18 – number of the visible ROUTE on top side of the map; P-00 – number of the visible PEG on the right side of the map; MD – map is shown in MODULUS mode;D 0005nT – scale of the gradient field 0 – 5 nT.

During Topographic survey express map is shown after each line is finished and disappears after “START” button is pressed at the beginning of eachroute. On top of the display are shown – number of the surveyed square, number of the last route that fits on the map (can be moved with control panel arrows), number of the first peg (can be moved with control panel arrows), as well as the mode of the express map. To improve informativeness of the map it can be presented in three different modes:

ST – standard mode – map shows in 2:1 proportion mostly positive and less negative anomalies of gradient readings.

INV – inversion mode – map is represented with only negative anomalies.

MD – modulus – map is represented as modulus of absolute readings of the gradient.

Next to letter R (range) display shows range width within which the map is built. The range is adjusted with control panel arrows to show anomalies from strongest to weakest. Each range has 17 levels of shadowing on display. 0-1250 nT is the widest range, which will allow to see only iron objects located close to surface. 0-5 nT is the range of the weakest anomalies.

Express map can also be viewed by simply choosing “MAP” option of the menu.

2.5 Site Layout setup

By switching to “PLAN” part of the menu, operator can place SQUARES to be surveyed in appropriate order, as well as automatically keep track of covered areas on a layout that shows areas which have been surveyed, partially surveyed or not surveyed. The darker the shadowing of the square the more surveyed it is. There are three levels of square coverage: completely surveyed – fully shadowed, partially surveyed – partially shadowed, not surveyed – not shadowed. The squares are numbered according to the order in which they are to be logged.

Picture 6. Site layout setup

Picture 6. Site layout setup

To add a square to the layout move cursor to the cell on the grid and press “ENTER”. The square will be numbered automatically. Repeated pressing of “ENTER” erases the square.

2.6 Memory. Transfer of data to computer

Internal memory of gradiometer allows it to store 125 000 gradient measurements tied to coordinates and time.

After survey is completed data from gradiometer is transferred to computer through COM port to be further processed with supplied software which can amend measurements and build grid and isoline or gray scale maps of the surveyed field.

To transfer data to computer or clear memory by erasing data choose MEMORY option of the menu, use control panel to choose the appropriate function and press ENTER.

3. Field work

3.1 Detailed area survey

Detailed area survey is used for detailed examination of the magnetic field gradient and its mapping. This mode is used during archaeological, geological research, humanitarian demining and other types of work.
Gradiometer MG-400 in “TOPOGR” mode (Topography/area survey) measures vertical gradient of magnetic field at adjustable speed of movement: 0.5; 1.0; 1.2; 1.5; 1.8 meters per second.

At any of the chosen speeds device makes 4 measurements per meter.

As you are moving with gradiometer along the route, a beep signal will indicate when measurements are taken – every 25 centimeters (4 per meter). Depending on the speed operator sets before beginning logging, gradiometer will adjust time between beep signals so that measurements are taken at the same rate. Use the beeps above meter marks to check whether you are moving too fast or too slow.

The area can be traversed in zigzag or parallel routes.

Area survey consists of two major parts: topographic work and magnetic logging.

3.1.1 Topographic work

Before magnetic surveying can begin, area should be broken down into squares of uniform straight lines along which gradient measurements will be taken. It is common to use squares that are 20 meters wide.

MG-400 allows to work with square widths of 10, 20, 40, and 80 meters. Squares can be turned into rectangles through their partial coverage.
To breakdown a 20 by 20 meter square with lines 1 meter apart from each other, it is best to use 20-meter-long cords running one meter apart and parallel to each other in the amount of 21 pieces. (Lines will have numbers from 0 to 20) You can also do the same with fewer cords if you do not mind moving the cord over to the next line after every line traverse and use pegs to mark the spots to move the cord to.

For best results it is highly recommended to move along routes that run in direction NORTH-SOUTH.

Begin, by marking corners of the future square.

Stretch the first 20 meter cord in the direction of your planned first route. Mark it’s beginning and end with pegs. Next, stretch your second cord from second peg at 90 degrees to the first cord and mark its end. Correct its position by using a tape measure to build a 28.28 meter diagonal (Pythagorean Theorem). Fourth and last corner and peg is marked by stretching 20 meter cords from first and third pegs.

(For squares with a side 10 meters long, length of diagonal will be 14.14 meters, with a side 40 meters – 56.57 meters, with a side 80 meters – 113.14 meters).

Picture 7. Square with a 20-meter side marked for magnetic surveying.

Picture 7. Square with a 20-meter side marked for magnetic surveying.

Now that corners of the grid are located, using tape measure, arrange pegs 1 meter apart at the beginning and end of all lines and run cords marked at every meter between them. The square is ready for magnetic logging.

3.1.2 Magnetic logging

Before starting work, gradiometer needs to warm up for at least 20-30 minutes. Find a spot for Checkpoint. Perform tunings as described in part 2.1.1-2.1.3

Enter squares into site PLAN and number them in order in which they are to be surveyed.

Switch to “TOPOGR” mode of the menu (Area Survey Mode). Display will show a list of parameters (marked “–“) that need to be entered using control panel.

Number of Squares

Number of Routes (in a square)

Number of Pegs (on a route)

Route length, m: 20; (can be 10, 20, 40, 80 m);

Distance between Routes, m: (can be 1 meter or bigger);

Speed of movement, m/s: (can be from 0.5 to 1.8 m/s);

Type of movement: (zigzag or parallel);

Map scale: (from 0-5nT to 0-1250 nT);

Route Direction: Surveying can be done with any direction of routes but preferred direction is S-N because the interference from tilts of gradiometer is lowest in this case.

Move to Checkpoint, face North, and press “START”. Following prompts on display, check settings and if necessary correct them:

Enter square number, route number, peg number from which surveying will begin (or continue).

By pressing “START” gradiometer readings are set to “0”. This sets level of field at Checkpointas base level from which all further measurements will be done.

Next by pressing “ENTER” switch to “Checkpoint” mode. This mode is used to log temperature changes in sensors during logging, if such changes exist.

Remember that device at checkpoint as well as logging routes should always be oriented to the North.

Logging should be performed in ZIGZAG fashion WITHOUT turning device 180 degrees. This procedure minimizes deviations in readings without losing productivity. It is possible because of duplicated Start button on the handle.

At checkpoint, first press Start when both operator and device are oriented to the North, then operator turns to face South WITHOUT turning device (device remains oriented to the North) and presses Start again.

When logging in PARALLEL traverses oriented SOUTH to NORTH, at Checkpoint device still prompts to register measurements’ difference in directions North and South, but device and operator should remain oriented to the North only, without turning to the South. Parallel traverse method is most effective from the standpoint of measurements’ deviation and accuracy but takes twice as much time and operator energy.
During Checkpoint stops it is important for operator to hold device in the same hand as when moving along routes during logging. The reason for this being that device is not held ideally straight but with a tilt which is different depending on direction of movement. Checkpoint stops compensate this defect.
Next by pressing “ENTER” switch to “Ready to log” mode. Movement along lines always begins in the lower left corner of the square, route 0, peg 0, since this is how software is going to map data. Figure 1.

Figure 1. Square coverage map in zigzag traverse mode

Figure 1. Square coverage map in zigzag traverse mode

 

You should start moving 1-1.5 meters before the square so that by the time you cross the first peg your speed of movement is constant. Logging begins by pressing “START” button as you are crossing peg 0 of route 0. From that moment on, operator corrects his speed so that at each sound signal, sensor bar is above the meter marks of the cord. At the end of the route gradiometer will make a long intermittent beeping sound indicating that the route is finished and you should move to the next route. The movement along next route will also begin by pressing “START”.

Operator needs to hold device in a way that makes vertical bar tilt as little as possible during movement. Stability of the device during movement affects quality of logging.

When the last route of the square is covered,display message prompts you to move to Checkpoint and register readings in two directions. Do it as described above. If this is not done, during computer processing appropriate amendments won’t be accounted for and quality of logging might go down.

During logging operator can change the speed of movement within the same square. For example, routes 1 to 8 with speed of 1 m/s, routes 9 to 15 with speed of 1.2 m/s, and routes 16 to 20 with speed 1.6 m/s. Frequency of measurements remains constant at all speeds – 4 measurements per meter.

Keep in mind that before changing the square width, for example from 20m to 40m, all readings from 20m squares should be downloaded to computer. Otherwise all earlier gathered data from 20m squares will be erased.

3.1.3 Express Map

To view express map just move to “MAP” cell of the Menu. Navigating through the map is done through the top line of display. Using arrow control buttons pick the number of the square (for example square 07), then transform it to the appropriate view buy using arrow buttons to choose the necessary range of readings (by changing the number from 1250 to 5 nT/m). Mode of the map – “Standard”, “Inversion”, or “Module” is changed by switching between “ST”, “IN”, or “MD”.

You can also navigate through map by changing the number of the first route or peg on the top line of display with arrow buttons.

When viewing squaresthat are 10 or 20 meters long, scrolling through positions is not available since all positions fit on display. When the square width is 40 or 80 meters, all pegs do not fit onto display and can be scrolled through with arrow buttons.

Routes and Pegs are also numbered along the edges of the map.

Routes on express map are numbered along left SHORT side of display beginning from bottom and going up: 1;4;9;12;16;20. Pegs are numbered along lower LONG side of display going from right to left: 0;5;10;15;19.

Map can be navigated with the help of control buttons.

3.1.4 Custom Problems and Solutions

  1. End of the route signal sounded before or after last peg:
    Operator moved along the route too fast or too slow. Use arrow buttons to move to the starting position of this route and repeat it.
  2. You cannot continue movement along the route because of an obstacle – pond, hay, bushes…

As you approach the obstacle press “START”. Device will stop logging and counting pegs. Move to the peg from which you can continue movement, use arrow buttons to set its number, press “START” and continue movement.

Use the same procedure if routes stop short at an obstacle – river, fence, etc… Use arrow buttons to switch not only to the next peg but also next route. For example, if during Zigzag traverse operator has to end 12throute on 16thpeg instead of the 20th because of an obstacle and begin the next route because of the same obstacle from 15thpeg instead of the 20th; stop logging by pressing “START” on 16thpeg of 12throute, use arrow buttons to move to 15thpeg of 13throute, move to that peg and after pressing “START” resume logging.

If during movement along the route operator stumbles and falls or hits the sensor bar on a stone, level of readings can shift and affect quality of the map. In this case it’s necessary to stop the traverse, return to Checkpoint, switch to Menu option “Checkpoint” and repeat adjustments in this mode. After it’s done, repeat the interrupted route to continue logging.

3. Battery charge runs out too fast.

Check to make sure batteries have identical voltage. If one of them is defective, replace all four, even out the voltage and install them.

Running out of charge sooner can also occur at low temperatures.

LCD display performance can also be affected by low temperatures, making images less sharp. It can be improved by increasing contrast. Work can be continued since it doesn’t affect functionality of gradiometer.

3.2 Scanning

Scanning allows to explore the area at random routes and speed. Usually this mode is used to search for metal objects – lost bore-wells, war artifacts, containers, pipes, etc…

Picture 8. “SCAN” mode. Gradient field over 4 pipelines located at the depth of 2-3 meters.

Picture 8. “SCAN” mode. Gradient field over 4 pipelines located at the depth of 2-3 meters.

In “SCAN” mode operator chooses 2, 5, or 10 measurements per second. Horizontal arrow buttons change the frequency of measurements while vertical arrows buttons change the scale of the graph.

Assemble gradiometer as described in paragraph 1.6

Turn it on in “SCAN” mode and warm it up for 20-30 minutes.

Explore the area and find a spot for Checkpoint. It should be area approximately 1.5 by 1.5 meters, within which magnetic field doesn’t vary by more than 1-2 nT and should be located at least 50 meters away from the roads with transport.

With help of a compass locate the directions of N, S, E, and W and mark them with pegs.

Perform tunings as described in paragraphs 2.3.1-2.3.4

If the approximate size of anomaly is known, the area should be traversed at such lines frequency that guarantees crossing the anomaly at least twice. For example, when trying to locate an object expected to have a 5 meter anomaly on the surface, distance between routes shouldn’t be over 2 meters.

When trying to locate stretched objects, like pipelines for example, search lines should run perpendicular to the length of objects.

To locate the maximum point of anomaly, first locate the maximum reading along the movement route, then locate the maximum reading perpendicular to the movement route.

4. Software Radius

In the software part of the manual we will refer to SQUARES as GRIDS since this is the term used by such software as SURFER so that we could achieve consistency with programs created by other manufacturers when processing our data with their programs is necessary.

Software Radius consists of four programs:

“term.exe” transfers data from gradiometer to computer as a binary file with (.pkt) extension

“level.exe” equalizes background magnetic field level across several grids (squares).

“mag.exe” converts binary information file into text file for creating maps of magnetic field gradient. This file corresponds to the format of grids (.grd) used by system SURFER (Golden Software)

“karta.exe” is designed for building isoline maps in (.bmp) format

Gradiometer kit includes USB-COM cable and a CD with drivers and software. Programs are also available for download from the website www.magnotracker.com

Programs “term.exe”, “mag.exe”, “level.exe”, and “karta.exe” are copied from the supplied disc to a folder on computer. Program ‘term.exe” transfers information from gradiometer to computer through a COM-port with a USB-COM cable. Before beginning work with “term.exe”, install USB driver for emulating COM-port.

This driver is installed from a supplied CD.

4.1 Connecting gradiometer to computer

First connect COM-cable to gradiometer with gradiometer power off. Next connect the cable to the turned on computer. Only then gradiometer power can be turned on. This order of procedures is safe for computer.

4.2 Working with software

4.2.1 Application “term.exe”

First, using the supplied USB-COM cable, connect MG-400 (plug RS232) to computer (USB) port.

Start “term.exe” application.

Turn on gradiometer, switch to menu mode “MEMORY”, then “Transfer data to computer”.

On computer click on File – Open port

 

After prompt window “Port open” opens, press ENTER on gradiometer to begin data transfer.

After message “Data transfer finished” on magnetometer, same message will pop up on computer.

On computer click on File – Save as and in the opened window choose a name for the file to be saved with.

pictires

During data processing the following prompt message may open:
“port is not open” – Data processing stops. USB driver for emulating COM-port is not installed.

4.2.2 Application “mag.exe”

After start of application main menu with three tabs opens – “File”, “Grid” (square), and “Calculate”.

In the “File” tab, click on “open file” and choose the file downloaded from magnetometer with “term.exe” application. The file has (.pkt) extension.

Move to “Grid” tab and enter parameters of your grid (square) data. Coordinates of the lower left corner of the grid should be entered in meters.

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Window control, grid parameters and number can be entered by using scrolling or typing numbers.

Choose the type of traverse (zigzag or parallel) used during logging by clicking on appropriate option.

Press OK when all parameters have been entered. The application will take you to main menu.

Click on “calculate” tab to begin data processing. After the application finishes processing the data a prompt “Calculation finished” opens.

As a result of data processing, three new files are created: namenq.txt, namenq.grd, and namenqxyz.txt.
“name” part of the file name is the name of the file created when saving data with “term.exe”application. “nq” – is the number of the grid being processed.

First file namenq.txt is the original binary file converted into text format. It can be used for original data analysis.

Second file namenq.grd is created with the extension of SURFER software. It is used for drawing isoline maps.

Third file namenqxyz.txt is the measurements of magnetic field gradient with coordinates. It can be used for drawing grids by other programs. Program “mag.exe” uses spline interpolation method for drawing grids.

During data processing the following prompt messages may open:

“No original file selected – select file” message opens if during entering parameters of the grid, no file was selected.

“Wrong grid number – reenter grid parameters” message opens if the number of the grid (square) chosen for processing is higher than number of grids created during logging.

“Original file error – route finish time missing!” or “Original file error – route start time missing!” messages may pop up when there was an error during data transfer from magnetometer to computer. Data processing stops.

“Selected grid contains no measurement data; reenter grid parameters” message opens when grid (square) with no logging data was selected.

After receiving one of the above messages, click on any icon and restart processing after reentering correct parameters.

“No readings at Checkpoint before logging – Temperature Drift correction not applied”

“No readings at Checkpointafter logging – TemperatureDrift correction not applied”

“Checkpointand logging azimuth do not coincide – TemperatureDrift correction not applied”

These messages are received when the methodology of data logging wasn’t followed and have informative character. Data processing continues.

4.2.3 Application “level.exe”

Application “level.exe” is used to equalize the background field level across several grids (squares). It is not obligatory for map drawing but when used, will create a uniform background (“0”) level field across several grids (squares).

The main menu of the application has one window – “FILE”.

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1. Click on “file” – the drop down menu will have two options – “Open grid files” and “Exit”.

2. Click on “Open grid files” – select the files with .grd extension created with application “mag.exe”. Hold Ctrl key on keyboard to select multiple files. After all files have been selected click OK.

Only grids with a shared side and of equal size can be equalized.

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In the drawing above all grids except grids 1 and 2 can be equalized.

Application creates grid files that have thename of the original file with addition of letter “u” at the end.

The application can give the following prompts:

  • “Size of the grid exceeds 300 x 300 nodes”. Application stops processing. Background field level cannot be equalized. This situation can happen if the grid size is not standard (standard sizes – 10×10, 20×20, 40×40, or 80×80 meters).
  • “Grids of different size selected” – after this prompt application stops processing. Background field level cannot be equalized.
  • “Grid (Grid name) is excluded. No shared sides.” Application continues processing without this grid (square).

Equalized grids (squares) can be seen as isoline maps of each grid (square) with application “karta.exe”.

Map of the entire site can be built with application “Surfer”.

4.2.4 Application “karta.exe”

Main menu of the program contains two tabs: “map” and “image”.

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Inside “map” tab click on “title” to enter name of the map.

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Click on “file”to enter map parameters:

  • Grid file name (name.grd) for drawing map;
  • Map color scale; image type;
  • Program mode (automatic drawing or manual parameters entry)

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For map coloring, choose one of three provided scales.
Automatic drawing means that program will determine field interval and isoline cross-section.
When entering parameters manually (select “NO” option) a new submenu opens. Enter field interval and isoline cross-section parameters. Field interval should be a multiple of cross sections.

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“Image type” allows to select the type of the map to be drawn:

  • “MAP” mode colors isolines depending on intensity of the field
  • “OUTLINE” mode does not draw isolines and only shows intensity of the field in selected colors.

Image type – MAP

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Image type – OUTLINE

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“Image” tab allows to change the size of the map on the screen.

The resulting file name.bmp contains isoline map of the chosen grid (square). This is a raster file which can be printed with standard Windows methods or copied into a document like Microsoft Word.

 

Warranty

Manufacturer warrants that for a period of 2 years following delivery, the product you have purchased will a) perform in accordance with published specifications and b) will be free from defects in materials or workmanship. Manufacturer’s liability is limited in all cases to the liquidation of the defect of the instrument. Warranty does not cover third parties and sellers and does not cover defects caused by abnormal work conditions, owner’s negligence and wear and tear. Warranty does not cover batteries. Shipping costs for repairs are covered by the owner and at owner’s expense.