EM38MK2xp - Geonics Limited

OPERATING INSTRUCTIONS

EM38-MK2 DATA LOGGING SYSTEM

FOR WINDOWS XP BASED FIELD COMPUTER

EM38MK2xp

Version 1.06

November, 2009

G

eonics

L

imited

1745 Meyerside Drive, Mississauga, Ontario, Canada L5T 1C6

Tel: (905) 670 9580 Fax: (905) 670 9204

E-mail: [email protected]

Table of Contents

1. Introduction ................................................................................................ 1

1.1 Program Requirements ......................................................................... 2

1.2 Installing EM38MK2xp......................................................................... 2

1.3 Running EM38MK2xp Program............................................................. 3

1.4 Main Menu......................................................................................... 3

Short description of Main Screen options ...............................................................4

2. Survey Setup ............................................................................................... 7

3. System Setup............................................................................................. 13

4. GPS Port Setup & Monitoring...................................................................... 17

4.1 GPS Port Setup.................................................................................. 17

4.1 Monitoring GPS Receiver Output ........................................................ 19

5. Profiles Options......................................................................................... 23

6. Logging Data............................................................................................ 27

6.1 Monitoring Mode .............................................................................. 27

Description of Monitoring Mode Options.............................................................30

6.2 Stand By Mode.................................................................................. 35

6.3 Logging Mode................................................................................... 36

6.4 Stand By Mode Field Options ............................................................. 37

Appendix A ....................................................................................................... 45

A.1 Description of Data File in EM38MK2xp Format................................... 45

A.2 Example of File in EM38MK2xp Format ............................................... 49

Appendix B ....................................................................................................... 51

B.1 Using the EM38MK2xp with a GPS Receiver ........................................ 51

B.2 Description of GGA and GSA Data Messages...................................... 52

1. Introduction

The Geonics EM38MK2xp Data Logging System (DAS70-XP) consists of a laptop field computer, data logging program EM38MK2xp, and associated cable to connect the computer to the Geonics

EM38-MK2 instrument. The program EM38MK2xp is designed for an IBM PC compatible computer and MS Windows XP/2000 operating system.

Two models of the EM38-MK2 are available: EM38-MK2-1 and EM38-MK2. Providing similar functionality, including the simultaneous measurement of both quad-phase (conductivity) and in-phase (magnetic susceptibility) components, the defining difference between the models is the number of included receiver coils: the EM38-MK2-1 includes one receiver coil with a 1 meter transmitter / receiver intercoil spacing; the EM38-MK2 includes two receiver coils with 0.5 and 1 meter intercoil spacings. All references to the EM38-MK2 in this manual are applicable to both

of the models described above.

The EM38MK2xp program acquires and records survey data from the EM38-MK2 system, under the control of the operator. It also records various field information such as survey line number (line name), starting station, increment, comments, etc. Readings are displayed in real time in mS/m

(conductivity) or ppt (in-phase) in both graphic and numeric modes. In addition, the program allows you to monitor the instrument output while data are not recorded. Program EM38MK2 also continuously monitors the EM38-MK2 measured components (Conductivity and Inphase), dipole mode (Vertical or Horizontal), state of fiducial marker, as well as GPS signal quality parameters (if connected to the system) without leaving the program.

The program allows the user to set the EM38-MK2 into a specific instrument mode of operation:

AUTO, Wheel, or Manual modes. In AUTO mode readings can be automatically recorded in desired time intervals. In Wheel mode readings are triggered by a counter installed at the wheel assembly, and in MANUAL mode readings are triggered manually by the operator. In AUTO and Wheel modes the program can record one combination of the EM38-MK2 components (Conductivity and

Inphase), two separations (0.5 and 1.0 m), and dipole mode (Vertical or Horizontal) per station.

In Manual mode any combination of dipole modes can be taken at each station, and data can be averaged at up to 100 samples per reading.

The EM38MK2xp will accept NMEA-0183 compatible data from a GPS receiver directly connected to a Windows XP/2000 based field computer. GPS data which are embedded in the EM38MK2xp data file can be processed later in the Geonics DAT38MK2 program. The connected GPS must be able to stream NMEA-0183 compatible messages. The EM38MK2xp uses two NMEA messages

GGA and GSA. While message GGA is mandatory, the GSA string is used only to provide information related to the GPS signal quality during data collection.

The EM38MK2xp program records data together with a time stamp at each station. Data files created with this program can be used to position a survey according to locations recorded separately by a

Global Positioning System (GPS). However direct GPS interface described above is highly recommended as much more accurate and simpler (for data processing) method of GPS positioning.

Survey setup parameters are saved in a file, therefore they can be automatically used during subsequent data collection sessions.

Data files are saved to the user selected data directory. Data file names, which can be set by the program based on the computer clock or user specified, have extension names N38. Files can be converted to M38 format and viewed in DAT38MK2 program.

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Number of readings in a data file is limited only by the hard drive capacity, however it is strongly recommended to avoid huge data files (i..e one to two hours long data files are adequate). The maximum speed of data collection is approximately 21 readings per second assuming 1 Hz (or less)

GPS input. In graphic display mode, a profile containing the last 150 data readings is displayed for each channel.

1.1 Program Requirements

To successfully use this software, you will need :

Computer

- PC field computer operating under Windows 2000 Pro, XP, or later,

- Minimum 256 Mb of RAM memory,

- CD drive or other mean to transfer files,

- minimum 800 x 600 pixel display resolution,

- serial Ports: one serial port for the instrument plus one serial port if directly connected GPS receiver is to be used (USB to multiple RS-232 ports and PCMCIA RS-232 adapters can be used).

Geonics EM38-MK2

The EM38-MK2 instrument with associated cables.

The EM38MK2xp program is stored on DAT38MK2 CD disk. All necessary initial files (with extension names .INI) are created in your field computer after the program is run for the first time.

Check that the file EM38MK2xp.EXE is included on the CD disk.

1.2 Installing EM38MK2xp

The program consists of a standalone file EM38MK2xp.exe, no DDLs nor other libraries are required to run this program. The program is usually installed during data processing program DAT38MK2 installation, it is placed in subdirectory LogData of the selected installation directory.

If the program file is included separately on the DAT38MK2 CD disk, or downloaded from a web site or e-mail server it can be installed by copying the EM38MK2xp.exe file to any directory on your hard disk. This can be performed by using Windows Explorer.

After you run the program for the first time it will create permanent initial files (.INI) which contain some of the program settings. If the above files do not exist on the default drive they will be created with default parameters during the first execution of the program.

The EM38MK2xp data files contain extension name N38 and their base names should be limited to 8 characters.

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1.3 Running EM38MK2xp Program

Start EM38MK2xp by double clicking the EM38MK2xp icon in the Start|Programs menu, in

Windows Explorer, or on the desktop if a shortcut was created. At the start, EM38MK2xp displays the following screen.

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The EM38MK2xp is a command button and dialog driven program. Command buttons can be executed by clicking with the left mouse button, or by pressing the indicated (underlined) character on the keyboard, or by using TAB to scroll through the buttons and ENTER to execute. In the Main

Screen of the program Up and Down arrow keys can be also used to scroll through the buttons.

The Main Screen appears always as the first window after the program is started. It contains the name of the program, its version number (right bottom corner), and list of command buttons with available options on the right side. The major , left portion of the window contains information about current survey and system settings. This section is updated in real time as soon as the program parameters are changed in dialogs.

1.4 Main Screen

The Main Screen always appears after the program is started. It contains the name of the program, its version number, and a list of buttons representing the available options. The EM38MK2xp Main

Screen is displayed below.

These options are selected by clicking on buttons, or from keyboard using TAB/ENTER or shortcuts indicated by underline label characters. In case of Main Screen buttons the

Down and Up arrow keys and <ENTER> can be used as well.

Short description for each of the options follows.

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Short description of Main Screen options

Monitor/Log

This option allows to monitor and log the EM38-MK2 output. Monitor/Log screen starts always in Monitor mode, and then after a data file is created Logging mode is available.

Monitor mode provides options: creating data file, monitoring the EM38-MK2 output and quality of GPS signal, specification of selected survey parameters.

Survey Setup

The Survey Setup dialog will be displayed. All survey settings (survey line name, increments, etc.) can be specified in this dialog.

System Setup

Dialog window that is associated with this option is used to set the type of Pause key, audio option, fiducial marker setup, unit type, and serial port numbers.

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Set GPS Port

The GPS Port Setup dialog allows to disable and enable GPS data acquisition. This option is also used to set the serial port number used for GPS input and to specify necessary serial port communication settings. GPS monitoring window can be accessed from this dialog as well.

Monitoring GPS

GPS monitoring window will be displayed and GPS receiver output can be monitored.

This option allows to send commands to the GPS receiver as well.

Profiles Options

The dialog which will allow you to specify colour and thickness of profile lines will appear.

This dialog provides also choice of grid lines selection used for profile display.

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Exit

This option will terminate the program execution.

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2. Survey Setup

The Survey Setup dialog, presented below, contains several parameters which affect two important procedures: instrument settings (instrument mode, frequency of data collection, etc.) and survey geometry layout (survey line names, line spacing, start station, station increment, etc.).

To select any option click on the corresponding drop-down list box or text box, or use TAB key to scroll to the option and then use mouse or the Down and Up keys in drop-down box (parameters that have only a few possible options), or keyboard for text box entry.

Description of Options and Parameters:

EM38-MK2 Mode

This option allows you to select the type of instrument survey mode. Set the EM38-MK2 mode of operation by selecting an item from the drop-down list box labeled EM38-MK2

Mode. Available modes are: Auto, Wheel, and Manual. These modes of operation are described below.

Auto Mode

Readings will be triggered automatically at a specified frequency (see option

Readings/s).

In Auto Mode only one dipole mode (Vertical or Horizontal) can be selected.

Wheel Mode

This mode is available only if the system is equipped with adapted (i.e. EM61) wheels.

Readings will be triggered automatically by a counter attached to the wheel.

In Wheel Mode only one dipole mode (Vertical or Horizontal) can be selected.

When Wheel mode is selected option Reading/s is not available, see figure below.

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Manual Mode

Readings will be taken only while the manual trigger (switch on the instrument console or a handle) is pressed.

In Manual Mode any combination of dipole modes (Vertical and Horizontal) can be selected.

Please note that when Manual mode is selected options the option Reading/s changes to option labeled Samples/Rdg.

In this mode any value but zero can be entered as the station increment.

Readings/second

When this option is available (only in Auto mode) activate text box by clicking with a mouse or using TAB key and then enter desired value.

This parameter describes number of readings per second that will be taken. Any number larger than zero can be entered, however the EM38-MK2 fixed frequency of data output is 21 readings per second. Therefore any entered value is rounded to the nearest possible base frequency of the instrument, i.e. user specified frequency of 20 readings/s will result in effective data acquisition rate of 21 readings/s (every reading is logged), 9 readings/s will cause program to log at a rate of 10.5 readings/s (every second reading from instrument output is logged), etc. At slower rates the difference between specified and effective frequencies is negligible.

Samples/Rdg (Samples per Reading)

When this option is highlighted the editor is activated and you can enter desired value. The editor accepts only numerical positive values.

This parameter describes number of readings that will be taken after the trigger switch is pressed. At the end of sampling time the logger will beep and an average value will be written in to the file and plotted on the screen. During the sampling period interval data are measured at approximately 20 readings per second. For example by specifying 10 samples,

0.5 second will be used at each station. The maximal sampling is 100 readings which corresponds to approximately 5 seconds at each station.

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This option could be used to improve quality of data in areas of high industrial noise, especially if the ground conductivity is relatively low (small response signal).

In cases when multiple sampling is not required (good signal to noise ratio) enter the value

0 or 1 and 1 reading per station will be taken.

This parameter is displayed only when the Manual Mode was selected.

Dipole Mode (instrument dipole mode)

Clicking on the down arrow next to the text box opens a drop-down box showing the available settings, or when the keyboard is used activate the text box and then by using up or down arrow keys select one of two or three available items: Vertical, Horizontal, and Both.

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When Manual mode was selected three settings are available: Vertical, Horizontal, and

Both. If Auto or Wheel mode was selected two available dipole modes are: Vertical or

Horizontal.

Survey Line (survey line name)

Activate text box by clicking with a mouse left button or using TAB key and then enter desired name (number) for the survey line.

This is a user’s tag number/name for the profile line. The length of the name can not exceed

8 characters. The line name is usually used as a coordinate perpendicular to the survey lines direction. For example, when survey lines are laid out along W-E direction stations describe

W-E coordinate, while Line names may describe S-N (vertical on a map) coordinate.

Line Incr. (survey line name)

Activate text box by clicking with a mouse or using TAB key and then enter desired for the survey line increment.

This parameter specifies the distance by which survey lines will be separated. This setting will be used to determine number (name) of the next survey line.

Sequence

When this option is highlighted and drop-down box is expanded use mouse or use Down or Up cursor key to toggle between two available settings: Alternate and One Way.

Alternate is used when neighboring lines are surveyed in the opposite direction, which is the most common procedure during field surveys.

One Way is used when each survey line is traversed in the same direction.

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The choice of this parameter will affect the default start station, a signature of the station increment, and line direction when parameters for the next survey lines is determined.

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Direction

Clicking on the down arrow next to the text box opens a drop-down box showing the available options, or when the keyboard is used activate the text box and then by using up or down arrow keys select one of four available settings: East, West, South, and North.

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This parameter indicates the heading of the survey line.

Start Station (start station of a survey line)

Activate text box by clicking or using TAB key and then enter the desired value for the start station.

This parameter specifies the starting station number for the selected survey line. This value is used in conjunction with Station Increment to calculate the current station number for display purposes.

Stn Increment (station increment)

Activate text box by clicking with a mouse or using TAB key and then enter the desired value for the station increment.

This parameter specifies the station increment for the selected survey line. This value is used in conjunction with Start Station to calculate the current station number for display purposes.

After all the parameters in the Survey Setup dialog are updated click on the button OK or press

ENTER key to accept the displayed settings. The program will return to the Main Screen. Updated settings will be written to the initial file and they will be given as default parameters in the subsequent Survey Setup dialog.

To return to original settings (state before this dialog was selected) click on the Cancel (X) button or press Esc key. All parameters will be reset to initial settings and the program will return to the

Main Screen.

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3. System Setup

This dialog allows you to specify the EM38-MK2 type, Marker, Pause Key selection, set Audio on/off, and select ports for the EM38-MK2, External Marker, and GPS receiver. The System Setup dialog is presented below.

Description of Parameters:

EM38-MK2 Type

Two models of the EM38-MK2 are available: EM38-MK2-1 and EM38-MK2. Providing similar functionality, including the simultaneous measurement of both quad-phase

(conductivity) and in-phase (magnetic susceptibility) components, the defining difference between the models is the number of included receiver coils: the EM38-MK2-1 includes one receiver coil with a 1 meter transmitter / receiver intercoil spacing; the EM38-MK2 includes two receiver coils with 0.5 and 1 meter intercoil spacings. The program default is the EM38-MK2.

Soft Marker (Software Based Marker)

A software based fiducial marker is available in addition to the standard fiducial markers

(located on the instrument panel or on the optional Extender Arm and the above described optional External Marker connected to one of the serial ports). All three types of fiducial markers provide the same function and are saved in the data file.

There are two available selections for the Soft Marker: Disabled and any numeric key.

When the latter option is selected pressing any numeric key (from 0 to 9) on the computer keypad during logging session will tag current station as a station with fiducial marker. It acts exactly the same way as a standard marker located on the instrument panel.

Enable the Soft Marker by selecting any numeric key or deactivate this option by selecting

Disabled (see Figure below).

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Pause key

Four selections are available:

any non numeric key, Enter, Space Bar, and P This feature is used to pause data recording during logging session. Default setting

any non numeric

key (numeric keys are reserved for the soft marker) can be changed to one of the three specific keys for field conditions where a logger key can be accidentally pushed causing unwanted stop of data logging.

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Audio

Two selections are available:

Yes or No. The audible click will be generated at each reading when this option is enabled. At fast rate (above 5 readings/s) the sound may appear not uniform, however this does not affect quality of data acquisition.

Display Units

Three selections are available:

Meters, Feet or US Survey Feet.

EM38-MK2 Port

The number of serial port that is assigned to the EM38-MK2. Available selections: COM1 to COM12. The program default is COM1. Communication parameters for the selected serial port are set by the program, since the EM38-MK2 operates at fixed settings: Baud

Rate (19200), Parity (N), Data Bits (8), and Bit Stop (1).

This port must be different than the port specified in the list box "GPS Port:" (see below) or in the GPS Port Setup dialog window (see chapter 4), otherwise a message will be displayed and ports will have to be reassigned.

Select port number in the drop-down list box (see Figure below).

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GPS Port

The number of serial port that is assigned to the GPS receiver. Available selections: COM1 to COM12. The program default is COM2. Communication parameters for the selected serial port can be set in GPS Port Setup dialog. The GPS port can be also assigned in the latter dialog.

This port must be different than the port specified as the EM38-MK2 serial port.

Select port number in the drop-down list box similarly to EM38-MK2 port assignment procedure.

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Ext. Marker Port (External Marker Port)

An optional External Marker can be connected to one of the available serial ports. This option displays the number of serial ports that are assigned to the External Marker. Available selections: Disabled, COM1, COM2, COM3, ... to COM12. The program default is None.

Select port number or deactivate External Marker by selecting Disabled in the drop-down list box (see Figure below).

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This port must be different than the port specified in the Set Port for GPS option (see next chapter), otherwise a message will be displayed and the ports will have to be reassigned. If

External Marker is located on the Extender Arm then The EM38-MK2 and Ext. Marker

Port must be the same.

After all the parameters in the System Setup dialog are updated click on the button OK or press

ENTER key to accept the displayed settings. The program will return to the Main Screen. Updated settings will be written to the initial file and they will be given as default parameters in the subsequent System Setup dialog.

To return to original settings (state before this dialog was selected) click on the Cancel (or window

X) button or press Esc key. All parameters will be reset to initial settings and the program will return to the Main Screen.

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4. GPS Port Setup & Monitoring

The GPS Port Setup dialog allows for enabling GPS input, and setting communication parameters for serial port associated with GPS input. GPS Monitoring window allows you monitoring the GPS output in terminal mode and to send NMEA commands to GPS receivers.

4.1 GPS Port Setup

After the Set Port for GPS button was clicked on (or executed from the keyboard) in the Main

Screen the Set Port for GPS dialog window appears on the screen. This dialog allows you to enable and disable the GPS input, select serial port for GPS input, and to specify serial communication parameters matching GPS receiver settings. The dialog is presented below.

Description of Options and Parameters:

GPS Input

This option allows you to Enable/Disable a serial port for GPS input. When Disabled is chosen logging and monitoring screens will display message “GPS disabled” in place of

GPS parameters.

The GPS Input can be Enabled even if there is no GPS system connected to the computer.

In such case data file will contain proper sequence of EM38-MK2 readings without any

GPS input.

Clicking on the down arrow next to the text box labeled GPS Input opens a drop-down box showing the available settings, or when the keyboard is used activate the text box by pressing TAB key and then by using up or down arrow keys select one of two available items: Enabled and Disabled.

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Serial Port

The number of serial port that is assigned to the GPS input. Available selections: COM1 to COM12. The program default is COM2. Communication parameters for the selected serial port can be determined in options described below.

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This port must be different than the port specified in the System Setup menu (for EM38-

MK2), otherwise a message will be displayed and ports will have to be reassigned.

Clicking on the down arrow next to the text box labeled Serial Port opens a drop-down box showing the available ports, or when the keyboard is used activate the text box by pressing

TAB key and then by using up or down arrow keys select one of available items.

Baud Rate

Specify Baud Rate for the output port, the selected value should match the Baud Rate of the GPS system, default is 9600. Available settings are: 4800, 9600, 19200, 31400, 57600, and 115200.

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Clicking on the down arrow next to the text box labeled Baud Rate opens a drop-down box showing the available parameters, or when the keyboard is used activate this text box by pressing TAB key and then by using up or down arrow keys select one of available items.

Parity

Select Parity for the output port, the parameter should much the Parity set in the GPS serial port settings. Available settings are None, Even, and Odd; default is N.

Clicking on the down arrow next to the text box labeled Parity opens a drop-down box showing the available parameters, or when the keyboard is used activate this text box by pressing TAB key and then by using up or down arrow keys select one of available items.

Data Bits

Specify Data Bits for the output port, the selected value should much settings in the GPS receiver, default is 8. Other available selection is 7.

Clicking on the down arrow next to the text box labeled Data Bits opens a drop-down box showing the available parameters, or when the keyboard is used activate this text box by pressing TAB key and then by using up or down arrow keys select one of available items.

Stop Bits

Specify Stop Bits for the output port, the selected value should much settings in the GPS receiver, default is 1. Available selections are 1 or 2.

Clicking on the down arrow next to the text box labeled Stop Bits opens a drop-down box showing the available parameters, or when the keyboard is used activate this text box by pressing TAB key and then by using up or down arrow keys select one of available items.

After all the parameters in the GPS Port Setup dialog are updated click on the button OK or press

ENTER key to accept the displayed settings. The program will return to the Main Screen. Updated settings will be written to the initial file and they will be given as default parameters in the subsequent Survey Setup dialog.

To return to original settings (state before this dialog was selected) click on the Cancel (X) button or press Esc key. All parameters will be reset to initial settings and the dialog window will disappear.

4.2 Monitoring GPS Receiver Output

After the Main Screen command button GPS Monitoring is clicked or executed by the keyboard the program will display the GPS Monitoring window in terminal mode. In this mode the screen is divided into three parts. The terminal window in the top portion of the screen displays the GPS receiver output. The middle portion labeled NMEA Command is used to display entered NMEA commands previously sent to the GPS receiver, and at the bottom, command buttons with available options (Pause/Go, Send, and Exit) is displayed. These buttons can be clicked on, executed by TAB key and ENTER keys, or by using shortcuts (pressing underlined letter keys). This screen is shown below.

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As soon as the EM38MK2xp screen is in terminal mode and the GPS is streaming data, each message transmitted by GPS receiver will appear in the top portion of the display (the end may be cut off if an NMEA message is longer than screen). The display is updated with the frequency the GPS receiver outputs data. This allows you to recognize the GPS update rate and type of messages being sent by the connected GPS. In cases where the GPS data is not received by the logger a message NO

DATA and current time will appear in the top window of the display, as shown below.

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The message NO DATA is normally updated with a rate of 7 seconds. This may indicate the following: serial port number not correctly specified in Set Port for GPS dialog, GPS receiver not sending any data, and not working or not connected GPS receiver. If the message is updated more often than 7

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20 seconds (i.e. every 1 or 2 seconds) or the display does not show legible characters, it is possible that the GPS is working correctly and is connected to the proper serial port, however communication parameters are not specified correctly. In most cases the Baud Rate or Parity must be adjusted.

The NO DATA message may also appear if the GPS data are received correctly, but the GPS receiver was set to send data with a time interval longer than 7 seconds. In this case the NO DATA message will be displayed in between GPS messages. This indicates that the GPS is working correctly, however the operator should consider adjustment of the GPS receiver output update rate. Most high resolution geophysical surveys require positioning update of 1 or 2 seconds, and a 5 seconds interval can be used only when the survey is carried out at an even pace and along relatively straight survey lines.

The monitoring display can be stopped any time by using button labeled Pause. At that time scrolling of the GPS output will be stopped, and the button will be labeled

Go. The next click (or keyboard action) on this button will activate receiving and display of GPS data.

The button labeled Send allows you to send a NMEA command to the GPS receiver. It is preferable if the GPS receiver parameters are set using the GPS manufacturer software or controller (GPS logger or panel keys). However,

when the operator is familiar with NMEA protocol and structure of

commands for a given GPS system, this function can be very convenient and useful when the update rate and enabling or disabling messages in the data stream is required.

After the button Send is clicked a dialog titled GPS Message is displayed and the beginning of the standard NMEA command,

$PASHS, or the last entered command is displayed. After the entire

NMEA command is typed in, click OK button or press the key

<ENTER> to send the command to the GPS receiver. Clicking the Cancel button or pressing the <Esc> key will cancel the command and hide the NMEA Message dialog. An example of a command that will enable the NMEA message

GSA is given in the below figure (it is assumed that the GPS receiver output serial port is A).

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After this command is received by the GPS receiver, the confirmation message will be send by the receiver ($PASHR, ACK*3D) and data stream will contain the message GSA ($PASHR,

NME,GSA,A,ON), see Figure below.

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Please note, that not every GPS system accepts and uses the same standard set of NMEA commands and messages. In addition, some GPS systems do not accept commands sent by the serial port at all.

The configuration of these type of receivers can be updated only by the controlling device (usually

GPS logger, controller, or the receiver panel keys).

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5. Profiles Options

After the Profiles Options button was clicked (or executed from the keyboard) in the Main Screen the Setup Profiles Options dialog window appears on the screen. This dialog allows you to enable and disable the display of each channel profile representing various combinations of component, dipole mode, and coil separation, specify color and thickness of profiles, and select type of grid lines. Please note that first four items correspond to 1 m coil separation (only these are valid if the

EM38-MK2-1 instrument type is used) while the bottom four items correspond to 0.5 m coils separation. The dialog is presented below.

Description of Options and Parameters:

Visible

To enable or disable displaying of each channel profile click on the corresponding button labeled Visible. Profiles of all channels with checked buttons will be displayed during data logging.

Regardless of which channels are chosen to be displayed as profiles, data for all channels data streamed by the instrument will be displayed in numeric form below profile display and all available data will be recorded in data file.

Color

To change colour of each profile click on the corresponding button (with colour line) labeled

Color (click to change). The dialog titled Color (presented below) will appear.

Select desired colour by clicking on a colour box (the selected colour box will be highlighted).

Click on the button OK or press ENTER key to accept the highlighted colour. The Color dialog will disappear and the colour of the appropriate channel button will updated. To cancel colour selection click Cancel (X) button or press Esc key.

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Thickness

Specify thickness of a profile for a desired channel by using one of four drop-down boxes labeled thickness. Thickness of a profile curve is expressed in pixels. Available settings are:

1, 2, 3, or 4 pixels.

Clicking on the down arrow next to the text box (labeled by number of pixels) opens a dropdown box showing available selection (see Figure below). Select thickness by clicking on the desired selection. If keyboard is used activate text box by pressing TAB key (till the box is highlighted) and then by using up or down arrow keys select one of available items.

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Grid Lines

Profiles for both components share the same graphic window, however each component has its own scale. This option allows you to select grid lines to be displayed (as thin grey lines) for conductivity or Inphase scale.

Minimum and maximum values for the component with selected grid lines are displayed as bold numerals. See figure below where grid lines are plotted for conductivity scale.

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After all the parameters in the Display Options dialog are updated click the button OK or press

ENTER key to accept the displayed settings. The program will return to the Main Screen. Updated

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settings will be written to the initial file and they will be given as default parameters in the subsequent Survey Setup dialog.

To return to original settings (state before this dialog was selected) click the Cancel (X) button or press Esc key. All parameters will be reset to initial settings and the dialog window will disappear.

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6. Logging Data

After the Logging button (in Main Screen) is clicked or executed by the keyboard, the program enters the logging session which contains three modes: Monitoring, Stand By and Logging. The program starts the logging session always in Monitoring mode. In this mode the EM38-MK2 readings, dipole mode, available inter-coil separations, and GPS parameters can be quickly examined and a data file can be created. The instrument can be also calibrated in Monitoring mode. After a data file is created in Monitoring mode, the program switches to Stand By mode and allows access to Logging mode. In Stand By mode instrument output can be monitored and some survey and logging parameters can be changed, and the Logging mode is used only to record data. Two modes

Stand By and Logging are toggled by GO and Pause buttons.

6.1 Monitoring Mode

The Monitor mode allows initial inspection of the range of the instrument readings at a particular site and monitoring the instrument and GPS receiver performance.

It is assumed that the instrument is turned ON prior to using this option. If the instrument is OFF or the instrument console is not connected to the computer the following message "Instrument

OFF or Disconnected" will appear (see Figure below).

Check the connection or turn the instrument ON and select the Monitor/Log option again.

Assuming that the instrument works properly the program will display the Monitor mode window.

The layout of the Monitor window is as follows:

The Monitor (as well as Stand by and Logging) window is divided into four sections.

One line of text in the top section provides survey parameters (used in Stand By and Logging modes) and instrument information. In Monitor mode this section displays: current display mode (Monitor, Stand By or Logging), survey mode (Auto, Wheel, or Manual), and user specified instrument dipole mode (Vertical, Horizontal or Both following label Dipole Mode:). The same line displays

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28 also state of Auto Calibration (ON or OFF). When fiducial marker is pressed then the label

M is displayed.

The second, largest graphic section will be used to display profiles while logging data. Numeric labels on the right side of profile window correspond to scale minimum (below the profile window) and maximum (above the profile window). The first value is associated with conductivity readings and the second number corresponds to Inphase readings. Values displayed in bold font indicate grid lines scale association.

The remaining bottom section contains a window with current EM38-MK2 readings (Conductivity and Inphase, and dipole mode), three frames (File Parameters, Line Parameters, and GPS information), and command buttons located on the right side of the screen.

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The EM38-MK2 readings and dipole mode are displayed from the left in order: conductivity and

Inphase for 1.0 m coil separation, then conductivity and Inphase for 0.5 coil separation, followed by dipole mode (Vertical or Horizontal). Displayed values are labeled: Cond 1 m, Inph 1 m, Cond

0.5 m, Inph 0.5 m, Dipole. Conductivity values are displayed in mS/m and Inphase values are given in ppt. The EM38-MK2 readings are updated approximately 21 times per second during the monitoring session.

When GPS is Disabled in the Set GPS Port dialog a message GPS Disabled will be displayed (please see Figure above). If the GPS port is Enabled and a working GPS receiver is connected to the field computer the Monitoring screen will display GPS parameters, as presented below.

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In the above Figure one line of the display is dedicated to show the GPS status. A label Positions will be used during data acquisition, it will provide the number of GPS positions saved in the data file. Below, two lines display the parameters describing the quality of GPS positions. A label DGPS

(Differential Global Positioning System) indicates that GPS readings are differentially corrected in real time, while label AGPS (Autonomous Global Positioning System) indicates lack of differential correction. On the right side of DGPS or AGPS label two green and white circles alternate. These two circles should alternate colours with the frequency of GPS update rate (usually 1 second intervals). If the circles do not change colours for long periods of time it means that the GPS system is not working or that it is not connected to the field computer. The next label

PDOP with a value varying between 0 and 99.9 represents an index called Position Dilution of Precision (

PDOP). This value is available only when messages both, GGA and GSA are received from GPS. The last label

Sat and following number shows number of currently tracked satellites. Refer to section 4 (Set Port for GPS), Appendix A, and to GPS manuals for more information about GPS parameters. Two bottom lines of the frame give current Latitude and Longitude of the instrument position (datum

WGS1984). Position is updated with frequency of GPS receiver stream.

Five command buttons located in the right bottom corner of the Monitor window lists the program functions available directly in the Monitor mode. Available options are as follows: Data File (create data file), Scale Readings (change scale for Conductivity and Inphase profile window), Calibrate

EM38-MK2 (auto calibration procedure), Delete Calibration (to remove Calibration factors), and

Exit (exits the Monitor mode and returns the program to Main Screen.

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Description of Monitoring Mode Options

Data File (create data file)

The log data file can be created in any directory. The name of the file is given by the field computer clock and it consists of month (2 digits), day (2 digits), hour (2 digits), and one alphabetic character A, B, C, etc. (If all letters during one hour are used use the Overwrite option). The Create Data File dialog is presented below.

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The file name can be specified in the Create Data File dialog using the Windows standard interface procedure. The EM38-MK2 data files cannot be appended.

Each data file in the field computer (raw data file) has an extension name N38 and it is created in the directory specified in Create Data File dialog. The N38 files are created in the instrument binary format. These files can be also converted to ASCII format and processed in the Geonics DAT38MK2 program.

After the file is specified click on the button OK or press ENTER key to accept and create data file. The program will switch Monitor mode to Stand By mode and the data file will be displayed on the screen.

To cancel selection and return to Monitoring mode tap the Cancel (X) button or press

Esc key.

Scale Readings (New Scale for Profile Plot)

Selecting New Scale option allows the operator to enter new scale parameters for the profile plot for each component. This option is available in Stand By mode as well.

The Reading Scale dialog will be displayed. It contains four text boxes for Minimum and

Maximum values of a new scale for profile plot of conductivity and Inphase. Current settings (minimum and maximum values) for the scale are displayed in the bottom right and top right corners of the plot area. The first numbers indicate scale for conductivity and the second (following slash) numbers are associated with Inphase scale. Values displayed in bold indicate the scale that is associated with grey grid lines.

After minimum and maximum values are specified click on the button OK or press ENTER key to accept new values and the profile plot area will be redrawn (see Figure below).

To ignore an entry and return to Stand By mode click on the Cancel (or Windows System

X) button or press Esc key, the dialog window will disappear and measurements can be continued.

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Calibrate EM38-MK2 (automatic calibration of EM38-MK2)

This option allows you to calibrate EM38-MK2 using automatic, software based method.

Calibration procedure is the same as described in the EM38-MK2 Operating Manual however here all the procedure is controlled by the program EM38MK2xp. During Calibration the program calculates proper factors for conductivity and Inphase at each coil separation and dipole mode. These values are saved in the logging computer memory as long as option

(Delete Calibrate) is executed or a new version of the program is transferred to Allegro.

It is recommended to perform Calibration at least once a day, after each battery change, when survey site is changed, etc. Calibration can be performed in Monitoring mode as well as later during logging session in Standby mode. Software based calibration that employs monopod is very easy, fast, and has several advantages:

1) it is relatively uniform and it does not depend on operator since height above the ground is determined by monopod.

2) it is very time efficient and easy to perform

3) all calibration factors are saved in the computer memory and are written in data file in every survey line header

4) procedure can be traced later for any data set. If Calibration is performed during logging session new and old calibration factors are written to data file.

After clicking on the Calibrate button (or executing this option using keyboard) a message is displayed:

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After the instrument is placed on the monopod in Vertical dipole mode click on the button Yes or press key Y (or Enter if button is highlighted). After button Yes was clicked a messages box disapears and a prompt Vertical Calibration is displayed. From now on all mesages and prompts will be written under plot section of the screen, in a line that is normally used to display labels for EM38-MK2 readings.

After the Vertical calibration is completed (usually few seconds) the program will beep and a message Rotate to Horizontal mode within 60 seconds will appear.

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In cases where rotating the instrument takes longer than 1 minute the program will display the message: Horizontal Mode Failed - Wait for Beep, and after a short delay (about 2 seconds) the program will return to normal operation.

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The program monitors instrument orientation and as soon as it detects that the EM38-

MK2 is in proper position it will display the following message: Preparing for Horizontal

Calibration. After a small delay required for stabilization the Horizontal Calibration will be performed.

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If for any reason the calibration is not succsesfull a proper message will be displayed.

Horizontal calibration takes normally 2 seconds and when the procedure is completed a confirmation message will be displayed (Figure below).

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After beep the above message disappears and program returns to normal operation. All calibration factors are saved in the field computer memory and will be used in consecutive program runnings. Unless a new version of the program is loaded the only possibility to delete (or reset to zero) calibration factors is using option Delete Calibration.

When calibration factors are used readings shown on the logging computer display usually differ from values displayed by the instrument console. To obtain same readings on the instrument console and on the computer display please use Delete Calibration option and then Calibrate again.

Delete Calibration (Delete Calibration factors)

After tapping Delete Calibration button (or executing this option using keyboard) the program immediately displays confirmation message:

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Please confirm by tapping button Yes, or pressing Key Y or Enter (if button Yes is highlighted) to delete (reset) calibration factors. After this is done readings displayed by the instrument console and the logging computer should be similar.

If this option was used by accident please tap button labeled No and all calibration factors will remain the same.

Exit (exit Monitor mode)

After clicking on the Exit button (or executing this option using keyboard) the program immediately returns to Main Screen.

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6.2 Stand By Mode

After the data file is created in Monitoring mode the program automatically switches the logging window to Stand By mode. This windows is similar to the Monitor mode however it contains survey parameters (file name, survey line name, etc.) and different set of options represented by buttons displayed at the bottom of the screen. The logging window in Stand By mode (before any data is recorded) is presented below.

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The main portion of the screen is occupied by the plot area which displays profiles (see Figure below which shows Stand By mode after some data were collected). Scale for conductivity and Inphase is labeled at the top and bottom of the plot window. The amplitude scale is divided by three to five grey grid lines. These grid lines may belong to conductivity or Inphase scale depending on the user preference (set in Display Options dialog). Assignment of grid lines is indicated by the bold font labels for the corresponding scale. In the case where the amplitude scale starts with a negative value, then the grid line corresponding to zero is always plotted as a thicker line.

Readings for conductivity and Inphase for each coil separation are shown in numeric form in a window below the plot area. Values of readings are labeled Cond 1 m, Inph 1 m, Cond 0.5 m,

Inph 0.5 m, Dipole. Conductivity values are displayed in mS/m and Inphase values are given in ppt.. Readings are followed by current dipole mode (Vertical or Horizontal). EM38-MK2 readings

(in numeric form) are updated in Stand By mode approximately 21 times per second. Profiles in the plot area are updated only during Logging mode when data are actually saved in the data file.

A section of the window at the top of the screen contains one line of text displaying survey and instrument related parameters. These are (from the left): logging mode (Stand By or Logging), survey mode (Auto, Wheel or Manual), user selected instrument mode dipole mode Vertical,

Horizontal, or Both (only in Manual mode) labeled Dipole Mode. When fiducial marker is active a label Marker is displayed in this line. Auto Calibration state is indicated by a label Auto Cal: On

(performed and active) or Auto Cal: Off (not used).

File and Survey Line parameters, and GPS information are displayed in three framed boxes at the bottom of the Stand By window. File Parameters frame displays: name of the data file, total number of survey lines, total number of stations collected in the file, and total time of surveying. The Line

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Parameters frame contains: name of current survey line, current station, number of stations in the current survey line, and time of surveying current line. In the Stand By mode the station number will not change. Stations in the EM38-MK2 program are incremented by station increment value after each reading is written to the data file.

The third frame is dedicated to showing the GPS status. A number following the label Position provides the number of GPS positions saved in the current data file. In Stand By mode the number of positions is not incremented (it is updated only when GPS position is written to the file).

Next two lines in this frame display parameters describing quality of GPS positions. A label DGPS

(Differential Global Positioning System) indicates that GPS readings are differentially corrected in real time, while label AGPS (Autonomous Global Positioning System) indicates lack of differential correction. On the right side of DGPS or AGPS label two green and white circles alternate. These two circles should alternate colours with the frequency of GPS update rate (usually 1 second intervals). If the circles do not change colours for long periods of time it means that the GPS system is not working or that it is not connected to the field computer. The next label

PDOP with a value varying between 0 and 99.9 represents an index called Position Dilution of Precision (

PDOP).

This value is available only when messages both, GGA and GSA are received from GPS. The last label

Sat and following number shows the number of currently tracked satellites. Two bottom lines of the frame give current Latitude and Longitude of the instrument position (datum WGS1984).

Position is updated with frequency of GPS receiver stream.

Several available field options (in form of command buttons) are listed at the bottom right corner of the Stand By mode window. They will be described in the following section 6.4.

6.3 Logging Mode

The Logging mode is enabled by clicking on the button labeled GO (log data) or pressing the shortcut key G (or the <

ENTER> key if button GO is highlighted) in Stand By mode. After this button is pressed the list of buttons at bottom of the screen will be replaced by one PAUSE button, label Stand By will be replaced by label Logging (at the top of the display) and data will be logged

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36 in the mode corresponding to the selected EM38-MK2 mode in the Survey Setup menu. All labels and parameters (with the exception of buttons representing Stan By mode options) are the same as in Stand By mode and they are described in the preceding section 6.2. The screen in Logging mode is presented below.

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After the screen changes to Logging mode the current station (label

Stn:) is updated according to the station interval. Similarly, if GPS Input was enabled, total number of GPS positions (label Po-

sitions) in the data file is incremented every time (usually once a second) GPS position is written to the file. Profile curves (for channels selected in Display Options window) are updated after each reading is written to the data file.

There is only one option available in the Logging mode - pause logging. After a Pause button is clicked or Pause key (any key or other Pause Key selected in Logger Setup window) is pressed the recording is stopped and the Logging mode returns to the Stand By mode. In Stand By mode the

EM38-MK2 data will be displayed with the update rate approximately 10 readings per second, however data will not be saved in the log file and profile curves will be not updated.

Exiting from the logging session and access to various field options are available only from the logging window in Stand By mode.

6.4 Stand By Mode Field Options

Several field options are available while the Logging window is in the Stand By mode. Options can be accessed directly from command buttons. Command buttons can be used by clicking on the desired button, or from the keyboard by pressing one of the shortcut keys (underlined characters on button labels) or by navigating using <TAB> key (sets button as a default button - default button is highlighted) and pressing <ENTER> key.

GO (log data) (start data logging)

Click on the GO button, or while using the keyboard press shortcut key <G> or if the button is a default button (highlighted) press <ENTER>. The logging window in Stand

By mode will change to Logging mode and logging data starts immediately.

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New Line (New Survey Line)

The New Line dialog is displayed (see Figure below). Selecting this option allows the operator to enter a new survey line number (name) and associated line parameters (Line Increment,

Line Sequence, Direction, Start Station, and Station Increment). The new line number and associated parameters are prompted by the program based on parameters specified in the Survey Setup menu.

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At the top of the dialog the last survey line name and the last logged station are displayed.

Default name for the new line is given based on the Line Increment parameter. The default

Start Station, direction of the Station Increment, and Direction are determined based on

Sequence selection. All these parameters can be overwritten by the user as described in the

Survey Setup menu description (chapter 2).

After all the parameters in the New Line dialog are updated click on the button OK or press ENTER key to accept the displayed settings. The program will return to the Logging window in Stand By mode. Survey line name (Curr. Line) name and current station (Sta-

tion) value will be updated and profile curves plot for former survey line will disappear.

To return to Stand By mode and current survey line settings (state before this dialog was selected) click on the Cancel (X) button or press Esc key, the dialog window will disappear.

New Stn.

(New Station)

Selecting this option allows the operator to enter a new station number (within the same survey line). The New Station dialog is displayed as shown below.

Current survey line, Start and Current station are displayed at the top of the dialog. The

New Station can be entered in the provided edit box labeled New Station.

Click on the button OK or press ENTER key to accept the new value. The program will return to the Logging window in Stand By mode. Current station (Station:) value will be

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38 updated and after data logging is activated the profile curves will have a small gap (two pixels) showing the new station entry (see Figure below).

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To return to Stand By mode and current survey line settings (state before this dialog was selected) click on the Cancel (X) button or press Esc key, the dialog window will disappear and measurements can be continued.

Cmnt (Comment)

Selecting this option allows the operator to enter a comment at any point of the survey.

A maximum of 11 characters can be entered as a comment. The Enter Comment dialog is displayed.

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Click on the button OK or press ENTER key to accept the comment entered in a text box of the dialog. The text of the comment is saved in the file with a corresponding time stamp and the program will return to the Logging window in Stand By mode.

To ignore an entry and return to Stand By mode click on the Cancel (X) button or press

Esc key, the dialog window will disappear and measurements can be continued.

Scale Rdgs (New Scale for Profile Plot)

Selecting Scale Readings option allows the operator to enter new scale parameters for the profile plot for each component, conductivity and Inphase.

The Enter Scale dialog will be displayed (Figure below). It contains four text boxes for

Minimum and Maximum values of a new scale for profile plot of conductivity and Inphase.

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Current settings (minimum and maximum values) for the scale are displayed in the bottom right and top right corners of the plot area (Conductivity/Inphase). Values displayed in bold indicate the scale that is associated with grey grid lines.

After minimum and maximum values are specified click on the button OK or press ENTER key to accept new values and the profile plot area will be redrawn (see Figure below).

To ignore an entry and return to Stand By mode tap the Cancel (X) button or press Esc key, the dialog window will disappear and measurements can be continued.

Profiles

(new options for profile plot display)

After the Profiles button was clicked or executed from the keyboard the Setup Display

Options dialog window appears on the screen. This dialog allows you to enable and disable the display of each channel profile, specify color and thickness of profiles, and select type of grid lines. The dialog is presented below.

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Please refer to chapter 5 where this dialog and its parameters are described in detail.

Click on the button OK or press ENTER key to accept updated display parameters. The dialog will disappear and profile plot area will be redrawn in Stand By mode.

To return to Stand By mode and current display options (state before this dialog was selected) click on the Cancel (X) button or press Esc key, the dialog window will disappear.

Calibrate (automatic calibration of EM38-MK2)

This option allows you to calibrate EM38-MK2 using automatic method.

After Calibration is selected in the pop up menu the Calibration dialog appears on the screen. This dialog allows you to proceed (Yes) or exit (No) the procedure in case the option was selected accidentaly. The dialog is presented below.

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Calibration procedure is the same as described in chapter 6.1 (Monitoring Mode). Please refer to above secion of the manual and follow all prompts that appear on the display.

Calibration factors will be written to the data file and displayed readings will be adjusted immediately after the Calibration procedure is completed.

Del Calibr. (remove calibration factors)

After Delete Calibration is selected in the pop up menu the following confirmation message appears on the screen:

Please confirm by clicking on the button Yes, or pressing Key Y or Enter (if button Yes is highlighted) to delete (reset) calibration factors. After this is done readings displayed by the instrument console and Allegro should be similar.

If this option was used by accident please tap button labeled No and all calibration factors will remain the same.

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Exit (exit data logging)

During data collection (in Stand By mode) a confirmation message will be displayed (there is no such message if Exit is performed in Monitoring mode) before program exits logging window.

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After the above message is confirmed the program stops logging, closes the data file and returns to the Main Screen.

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Appendix A

A.1 Description of Data File in EM38MK2xp Format

Each record contains 26 characters, including line feed at the end of each record.

Header of the file (contains two records starting with characters E and H)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

E M 3 8 M K 2 V 1 0 0

Survey Type

UT ID IM IC CS CT 10

H File Name Time/Samples 10

EM38MK2 - identification of program file

V100 - version number (1.00)

Survey Type - GPS (if GPS Input Enabled) or GRD (grid)

UT - unit type (0 = meters, 1 = feet)

ID - EM38-MK2 Dipole Mode

(0 = Vertical, 1 = Horizontal, 2- Both )

IM - EM38MK2 survey mode

(0 =Auto, 2 =Manual)

IC - not used ( 0 - fixed)

CS - instrument type ( 1 = EM38-MK2-1, 2 = EM38-MK2)

CT - type of logging computer ( =1 fixed)

File Name - file name, maximum 8 characters

Time/Samples - this field depends on EM38MK2 survey mode

Auto Mode - Time Increment in seconds

Manual Mode - Samples/Reading

10 - Line Feed character

O

O

Header at the start of survey line (four records starting with L, B, A, Z)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

L Line Name (8 characters) 10

B

A Dir

Start Station (Format F11.2)

Station Increment (Format F11.2)

10

10

O

O

Z D D M M Y Y Y Y

O 1

H H : M M : S S

Calibration for Q/P 1.0 m (F10.3) Former Cal. for Q/P 1.0 m (F10.3)

O 2 Calibration for Q/P 0.5 m (F10.3) Former Cal. for Q/P 0.5 m (F10.3)

3

4

Calibration for I/P V 1.0 m (F10.3)

Calibration for I/P V 0.5 m (F10.3)

Former Cal. for I/P V 1.0 m (F10.3)

Former Cal. for I/P V 0.5 m (F10.3)

5 Calibration for I/P H 1.0 m (F10.3)

6 Calibration for I/P H 0.5 m (F10.3)

Former Cal. for I/P H 1.0 m (F10.3)

Former Cal. for I/P H 0.5 m (F10.3)

Line Name - Line Name, maximum 8 characters

Start Station - Start Station for the Line, format F11.2

Dir - Direction of the Line (E, W, N, or S)

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10

10

10

10

10

10

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Station Inc. - Station Increment, format F11.3

Date - Date when Line was created, format DD-MM-YYYY

Time - Real Time when Line was created, format HH:MM:SS

O1 - Calibration factor - conductivity 1.0 m coils (current and former)

O2 - Calibration factor - conductivity 0.5 m coils (current and former)

O3 - Calibration factor - Inphase 1.0 m, V mode (current and former)

O4 - Calibration factor - Inphase 0.5 m, V mode (current and former)

O5 - Calibration factor - Inphase 0.5 m, H mode (current and former)

O6 - Calibration factor - Inphase 0.5 m, H mode (current and former)

10 - Line Feed character

Timer Relation

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

*

Computer Time (Format HH:MM:SS.sss) Time Stamp in ms (10 digits)

10

Indicates relation between computer clock and the program timer. This record links timer in milliseconds and computer time (local time) in format HH:MM:SS.sss. This record is written to the file each time a new new line is entered.

Reading

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

I

Gn 1h 1l 2h 2l 3h 3l 4h 4l 5h 5l 6h 6l Time Stamp in ms (10 digits)

10

I - indicator T, t, or 2

T - first reading at the EM38-MK2-2 station (default for Auto mode)

t - first reading at the EM38-MK2-1 station (default for Auto mode)

2 - second reading at station (possibble only in Manual mode)

Gn - information byte, one character parameter, the ASCII number of this character indicates following:

Bit

5

4

7

6

3

2

1

0

Decimal

128

64

32

16

8

4

2

1

Value and Meaning

0

not used

0

not used

0

not used

Ext. Marker = 1

used

= 0

otherwise

Soft Marker = 1

used

= 0

otherwise

Dipole Mode = 1

Vertical

= 0

Horizontal

Marker = 1

no marker

= 0

trigger pressed

0

not used

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1h - higher byte of the 2’s complement Hex number of Channel 1

1l - lower byte of Channel 1

2h - higher byte of the 2’s complement Hex number of Channel 2

2l - lower byte of Channel 2

3h - higher byte of the 2’s complement Hex number of Channel 3

3l - lower byte of Channel 3

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Geonics Limited

4h - higher byte of the 2’s complement Hex number of Channel 4

4l - lower byte of Channel 4

5h - higher byte of the 2’s complement Hex number of Channel 5

5l - lower byte of Channel 5

6h - higher byte of the 2’s complement Hex number of Channel 6

6l - lower byte of Channel 6

Time Stamp - time in ms from the Windows start (resets every 49.7 days).

The time in milliseconds can be linked with the computer local time by using Times in line started by * (see Timer Relation).

10 - Line Feed character

Channel Information

Channel 1 - Conductivity for coil separation 0.5 m

Channel 2 - Inphase for coil separation 0.5 m

Channel 3 - Conductivity for coil separation 1.0 m

Channel 4 - Inphase for coil separation 1.0 m

Channel 5 - Temperature for coil separation 0.5 m

Channel 6 - Temperature for coil separation 1.0 m

Multiply Channels 1 to 4 according to following formulas to obtain Conductivity or Inphase readings in mS/m or ppt.

(In EM38-MK2-1 data only channels 3, 4, and 6 are valid).

Reading (Conductivity) = (Channel x 5 / 1024 - 160) x 8 (channel 1 or 3)

Reading (Inphase 1.0 m) = (Channel x 5 / 1024 - 160) x 8 x 0.028819 (channel 4)

Reading (Inphase 0.5 m) = (Channel x 5 / 1024 - 160) x 8 x 0.00720475 (channel 2)

Multiply Channels 5 and 6 according to the expression given below obtain Temperature readings in degrees.

Temperature (for 1.0 or 5.0 m) = Channel x 100 / 13107 - 50

Comment

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

C

Comment (maximum 11 characters) Time Stamp in ms (10 digits)

10

New Station

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

S

New Station (Format 11.2) Time Stamp in ms (10 digits)

10

Calibration

When Calibration is performed during data logging then record for each component/coil separation/ dipole mode contains two factors. First value corresponds to the current calibration and the second, following value shows former calibration factor. Calibration values is always recorded as a block of six record, each record represents values for different component/coil separation and in case of

Inphase dipole mode settings.

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O

O

O

O

O

O

5

6

1

2

3

4

Calibration values placed in Line Header do not contain second, former values till calibration is performed during data logging, in this case they are set to zero.

Calibration for Q/P 1.0 m (F10.3)

Calibration for Q/P 0.5 m (F10.3)

Calibration for I/P V 1.0 m (F10.3)

Calibration for I/P V 0.5 m (F10.3)

Calibration for I/P H 1.0 m (F10.3)

Calibration for I/P H 0.5 m (F10.3)

Former Cal. for Q/P 1.0 m (F10.3)

Former Cal. for Q/P 0.5 m (F10.3)

Former Cal. for I/P V 1.0 m (F10.3)

Former Cal. for I/P V 0.5 m (F10.3)

Former Cal. for I/P H 1.0 m (F10.3)

Former Cal. for I/P H 0.5 m (F10.3)

10

10

10

10

10

10

O1 - Calibration factor - conductivity 1.0 m coils (current and former)

O2 - Calibration factor - conductivity 0.5 m coils (current and former)

O3 - Calibration factor - Inphase 1.0 m, V mode (current and former)

O4 - Calibration factor - Inphase 0.5 m, V mode (current and former)

O5 - Calibration factor - Inphase 0.5 m, H mode (current and former)

O6 - Calibration factor - Inphase 0.5 m, H mode (current and former)

10 - Line Feed character

GPS Data Message Records

#

!

Each GPS record (GGA Message) is broken in to several 24 characters strings and placed in the

EM38MK2 data file which contains 26 characters long records, including one character indicator and line feed at the end of each record. The GPS sequence starts at the line which contains character @ as the first character, then records that contain continuation of the same message start with character #. The GPS sequence ends with a line starting with the character !. The last line contains logger time stamp in milliseconds for given GPS reading. A sample of the GPS message written in

EM38MK2xp format is given below.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

@

$ G P G G A , h h m m s s .

s s , d d m m

23 24 25 26

. m m

10

# m

#

, m m , s , d d d m m . m m m m p p .

p , s a a a a a .

a a , m u ,

, s

+

, x x n , q q x x .

10

10 x , M , s s s , a a a * c c CR LF

Time Stamp in milliseconds

10

10

The GPS sequence may contain 4 to 6 records. Component of the GGA message may differ in length, however they are placed in the same number of columns. Refer to Appendix B (section B.2) for definition of each component of GGA data message.

48

Geonics Limited EM38MK2xp Data Logging System (DAS70-XP)

49

48

Geonics Limited

A.2 Example of Data File in EM38MK2xp Format

The EM38MK2 data file records are written in binary format, therefore the file may have different shape when displayed or printed, depending on particular video or printer settings.

EM38MK2 W115GPS00002 1

H 090916A 0.100

L0

B 0.00

AS 1.000

Z09092008 15:41:45

O1 112.765 0.000

O2 23.365 0.000

O3 5.127 0.000

O4 2.259 0.000

O5 15.823 0.000

O6 16.235 0.000

*16:49:17.000 40102085

T ’@ÁEÿÿƒ£ÛÛ 40165321

T …

¿AÿÿvƒÛÛ 40165416

@$GPGGA,223956.00,4336.59

#316,N,07936.65071,W,2,4,

#3,134.93,M,-35,M,4,118*5

#C

! 40165402

T ‡vÁ}ÿÿ~åÛÛ 40165511

@$GPGSA,A,3,,,,,,28,,17,1

#1,08,,,09.3,02.7,08.8*09

#

! 40165484

T ”ãÀàÿÿ……ÛÛ 40165606

T ‰ÛÃ ÿÿ «ÛÛ 40165700

T ¤(à ÿÿ¤WÛÛ 40165795

T •÷ÛñÿÿŽ£ÛÛ 40165890

T †/Àlÿÿ‚1⁄4ÛÛ 40165985

T †!¿ ÿÿ~4ÛÛ 40166080

T ˆ%Áîÿÿ„’ÛÛ 40166175

T ”Áèÿÿ3ÎÛÛ 40166270

T Š Âóÿÿ…<ÛÛ 40166365

T ¯ áõÿÿ ÛÛ 40166460

@$GPGGA,223957.00,4336.59

#315,N,07936.65071,W,2,4,

#3,135.10,M,-35,M,4,118*5

#4

! 40166401

@$GPGSA,A,3,,,,,,28,,17,1

#1,08,,,09.3,02.7,08.8*09

#

! 40166498

T Š1⁄2Æ‘ÿÿ…‚ÛÛ 40166555

T …è3⁄4Èÿÿ‚tÛÛ 40166650

T †„3⁄4ƒÿÿ ¯ÛÛ 40166745

T ‡ÿÁåÿÿa ÛÛ 40166839

T ’2Á~ÿÿ„TÛÛ 40166934

T ®ŽÝˆÿÿŸüÛÛ 40167124

T †

ÁZÿÿ3ÂÛÛ 40167219

T †þ¿ìÿÿƒÛÛ 40167314

T †ž¿¸ÿÿ~²ÛÛ 40167409

@$GPGGA,223958.00,4336.59

#312,N,07936.65069,W,2,4,

#3,135.25,M,-35,M,5,118*5

#2

! 40167401

............

EM38MK2xp Data Logging System (DAS70-XP)

49

Appendix B

B.1 Using the EM38MK2xp with a GPS Receiver

The EM38MK2xp program accepts input from GPS receiver that stream NMEA-0183 compatible data through their output port. The program uses two NMEA messages: GGA and GSA. The entire

GGA message is used later by the DAT38MK2 program, while the GSA message is used only to display PDOP index on the logger screen.

The GPS system means (control device, receiver panel, or manufacturer software) must be used to set GPS receiver communication parameters, to specify frequency of GPS output, and number and type of NMEA messages sent by the GPS system output port. Any GPS system can send various

NMEA messages.

It is important to select only two messages (GGA and GSA) that are actually

used by EM38MK2xp. The program will accept any GPS string sent by the GPS receiver, however it uses time to process GPS data that is not being used. Therefore, selecting a larger number of

NMEA messages for GPS output will result in slower data acquisition of EM38MK2xp. Normally, the EM38MK2xp running in Windows XP based logger uses less than 100 ms to process and record

GPS data from two NMEA messages, GGA and GSA.

Only message GGA is necessary to position EM38-MK2 data. If message GSA is not available in a particular system, the EM38-MK2 will function and record position data based on GGA message.

Lack of GSA message will result in PDOP index displayed as Not Available (N/A) on the logger display. Using message GGA alone will also result in slightly faster operation of the program. The speed can be further improved by setting higher Baud Rate (if it is supported by the employed GPS receiver) in Set GPS Port menu.

The EM38MK2xp dedicates portion of the display and shows GPS status in a frame box. A number following the label Position provides the number of GPS positions saved in the current data file.

Next two lines in this frame display parameters describing quality of GPS positions. A label DGPS

(Differential Global Positioning System) indicates that GPS readings are differentially corrected in real time, while label AGPS (Autonomous Global Positioning System) indicates lack of differential correction. On the right side of DGPS or AGPS label two green and white circles alternate. These two circles should alternate colours with the frequency of GPS update rate (usually 1 second intervals). If the circles do not change colours for long periods of time it means that the GPS system is not working or that it is not connected to the field computer.

The next label

PDOP with a value varying between 0 and 99.9 represents an index called Position

Dilution of Precision (

PDOP). This value is available only when messages both, GGA and GSA are received from GPS. This index measures the strength of satellite coverage for a given area. PDOP is affected by the number of satellites visible and their relative positions in the sky. The smaller the number of PDOP the stronger the satellite coverage is. When there are more than 5 satellites widely spaced visible, the PDOP is 4 or less. However, when there are less satellites visible, or they are unevenly spaced in the sky, PDOP values can be 6 or higher. In most cases, the PDOP in an open sky is less than 3, and most accuracies given for many GPS systems are given for this norm.

Refer to GPS documentation and literature for more information related to error sources of GPS positioning.

The last label

Sat and following number shows number of currently tracked satellites.

Two bottom lines of the frame give current Latitude and Longitude of the instrument position

(datum WGS1984). Position is updated with frequency of GPS receiver stream.

EM38MK2xp Data Logging System (DAS70-XP)

51

B.2 Description of GGA and GSA Data Messages

GGA Data Message

The GGA message contains the GPS position information and it is the most widely used NMEA data message. This message takes the following form:

$GPGGA,hhmmss.ss,ddmm.mmmmm,s,dddmm.mmmmm,s,n,qq,pp.p,saaaaa.aa,u,

+xxxx.x,M,sss,aaaa*cc<CR><LF>

Definition of GGA message component:

s n hhmmss.ss ddmm.mmmmm

UTC time in hours, minutes, seconds of the GPS position

Latitude in degrees, minutes, and decimal minutes

s

s=N or s=S, for North and South latitude

dddmm.mmmmm

Longitude in degrees, minutes, and decimal minutes s=E or s=W, for East and West longitude

Quality indicator, 0 = no position, 1 = raw, no differentially corrected position, 2 = differentially corrected position, 9 = position computed

qq pp.p saaaaa.aa u

+xxxx.x

M sss aaaa

*cc

<CR><LF>

using almanac information

Number of satellites used in position computation

HDOP = 0.0 to 99.9

Antenna altitude

Altitude units, M=meters

Checksum

Carriage return and Line feed

Geoidal separation (requires geoidal height option)

Geoidal separation units, M = meters

Age of differential corrections in seconds

Base station identification

GSA Data Message

The GSA message contains active satellites and PDOP value. The GSA message is given in the following form:

$GPGSA,c1,d1,d2,d3,d4,d5,d6,d7,d8,d9,d10,d11,d12,d13,f1,f2,f3*cc<CR><LF>

Definition of GSA message components:

c1 d1 d2-d13 f1 f2 f3

*cc

<CR><LF>

Mode, M = manual, A = automatic

Mode, 2 = 2D, 3 = 3D

Satellites used in position computation (range 0 to 32)

PDOP (range 0 to 99.9)

HDOP (range 0 to 99.9)

VDOP (range 0 to 99.9)

Checksum

Carriage return and Line Feed

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