Geonics Limited EM38-MK2 Operating Instructions Manual

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OPERATING INSTRUCTIONS

EM38-MK2 DATA LOGGING SYSTEM

FOR FIELD COMPUTER Allegro CX Field PC

EM38MK2

Version 1.15

March, 2008

1745 Meyerside Drive, Mississauga, Ontario, Canada L5T 1C6 Tel: (905) 670 9580 Fax: (905) 670 9204

Geonics Limited

E-mail: geonics@geonics.com

Table of Contents

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

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

1.2 Installing EM38MK2 ............................................................................ 2

1.3 Data Files Transfer ............................................................................... 2

1.4 Running EM38MK2 Program................................................................ 3

1.5 Main Menu......................................................................................... 3

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

2. Survey Setup ............................................................................................... 5

3. Logger Setup............................................................................................... 9

3.1 Bluetooth Connection of EM38-MK2 and Allegro CX ........................... 10

4. Set Port for GPS......................................................................................... 13

4.1 Monitoring GPS Receiver Output ........................................................ 15

5. Display Options ........................................................................................ 19

6. Logging Data............................................................................................ 21

6.1 Monitoring Mode .............................................................................. 21

Description of Monitoring Mode options..............................................................23

6.2 Stand By Mode.................................................................................. 24

6.3 Logging Mode................................................................................... 25

6.4 Stand By Mode Field Options ............................................................. 26

7. View Data Files........................................................................................... 31

Appendix A ....................................................................................................... 35

A.1 Description of Data File in EM38MK2 Format ...................................... 35

A.2 Example of File in EM38MK2 Format .................................................. 38

Appendix B ....................................................................................................... 39

B.1 Using the EM38MK2 with a GPS Receiver............................................ 39

B.2 Description of GGA and GSA Data Messages...................................... 40

1. Introduction

The EM38-MK2 data acquisition system (DAS70-CX) includes: an Allegro CX eld computer which is Bluetooth enabled; EM38MK2 software for data acquisition (programmed for the Allegro CX MS Windows CE.NET V4.2 operating system, specically); DAT38MK2 software for data processing; and cables to connect the eld computer to either the instrument and / or another serial device.

Two models of the EM38-MK2 are available: EM38-MK2-1 and EM38-MK2-2. Providing similar functionality, including the simultaneous measurement of both quad-phase (conductivity) and in-phase (magnetic susceptibility) components, the dening 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-MK2-2 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.

Program EM38MK2 acquires and records survey data from the EM38-MK2 system, under the control of the operator. It also records various eld 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 ducial 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 EM38MK2 into a specic instrument mode of operation: AUTO or Manual modes. In AUTO mode readings can be automatically recorded in desired time intervals, and in MANUAL mode readings are triggered manually by the operator. In AUTO mode the program can record the EM38-MK2 components (Conductivity and Inphase) and one 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 EM38MK2 will accept NMEA-0183 compatible data from a GPS receiver directly connected to an Allegro eld computer. GPS data which are embedded in the EM38MK2 data le can be processed later in the Geonics DAT38MK2 program. The connected GPS must be able to stream NMEA-0183 compatible messages. The EM38MK2 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 EM38MK2 program records data together with a time stamp at each station. Data les 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 le, therefore they can be automatically used during subsequent data collection sessions.

The program has an option that allows you to view data les. Data les are saved to the programs current data directory by default. Data le names, which can be set by the program based on the computer clock or user specied, have extension names P38. Files can be transferred to a PC computer using a memory card, or by a serial or USB port using the MS ActiveSync program.

Over 1,000,000 readings can be collected in the Allegro eld computer with a standard memory of 64 Mb. The maximum speed of data collection is approximately 21 readings per second assuming 1 Hz (or less) GPS input. In graphic display mode, a prole containing the last 135 data readings is displayed for each component.

EM38MK2 Data Logging System (DAS70-CX)

1.1 Program Requirements

To successfully use this software, you will need :

Computer

Field computer Allegro CX Installed MS ActiveSync software (Version 3.50 or later) in desktop PC, or alternatively

PCMCIA memory card to transfer les.

Geonics EM38-MK2

The EM38-MK2 instrument with associated cables.

The EM38MK2 program for Allegro CX is stored on DAT38MK2 CD disk. All necessary initial les (with extension names .INI) as well as data folder (DATA38MK2) are created in your eld computer after the program is run for the rst time. Check that the le EM38MK2.EXE is included in AllegroCX directory on the CD disk.

1.2 Installing EM38MK2

While using the Allegro CX the EM38MK2.exe le should be transferred from a desktop PC using MS ActiveSync software and USB or serial cable provided by manufacturer. Optionally the program can be transferred to an Allegro using the PC memory card.

It is recommended that the program be placed in non-volatile solid state storage. This memory is represented in the Allegro by the C_Drive icon. In the My Computer on the Allegro, double-tap on C_Drive icon, then folder C_Program Files will appear. The EM38MK2 program can be placed in C_Program Files. Folders for data les should be also created in C_Drive, which is a safe area to store data. The program creates folder DATA38MK2 which is the default folder for EM38MK2 les.

For more information about data storage options, refer to Chapter 3 of the Allegro CX manual.

1.3 Data Files Transfer

Data les are saved in the Allegro with extension N38. Transfer of les to desktop PC can be performed with MS ActiveSync or by PC memory card. Data les with extension N38 are binary raw data les. These les have to be converted to DAT38MK2 format with extension M38 (option "Convert Files" in DAT38MK2). They can then be processed in the DAT38MK2 program.

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1.4 Running EM38MK2 Program

To run the EM38MK2 program, locate it in the C_Program Files and double-tap its icon. The EM38MK2 is a Windows CE based, button and dialog driven program designed to be simple to use. Although the program fully supports touchscreen interface, keyboard entry may be convenient in some eld applications. The EM38MK2 can be fully operated from the keyboard when touchscreen functions are disabled by the user.

Options represented by the command buttons can be accessed by a single tap on the button. Buttons can also be selected from the keyboard by using shortcuts (pressing key corresponding to underline letter in button caption or by selecting button by pressing TAB and then execute by pressing EN- TER. Shortcuts are the fastest way of accessing options represented by buttons.

Most options in the dialog windows are given in the form of text boxes and drop-down boxes which can be accessed using touchscreen or by the keyboard. Each dialog window has a title bar with a caption describing the dialog function and two buttons OK and X (Cancel). The OK button (or key ENTER) conrms dialog selection. Tapping on the Cancel button (or pressing Esc key) closes the dialog and returns to the initial selection.

1.5 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 EM38MK2 Main Screen is displayed below.

EM38MK2 Data Logging System (DAS70-CX)

These options are selected by using tapping buttons, or from keyboard using TAB/ENTER or shortcuts indicated by underline label characters. The Main Screen buttons can be controlled with the Down and Up arrow keys and <ENTER>.

Short description for each of the options follows.

Short description of Main Screen options

Monitor/Log

This option allows to monitor and log the EM38MK2 output. Monitor/Log screen starts always in Monitor mode, and then after a data le is created Logging mode is available. Monitor mode provides initial inspection of the range of the instrument readings at the particular site, instrument calibration, monitoring the instrument performance, and quick inspection of the instrument settings.

Survey Setup

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

Logger Setup

Dialog window that is associated with this option is used to set the instrument type, serial port number or Bluetooth connection, and type of pause key.

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.

Display Options

The dialog which will allow you to specify colour and thickness of prole lines will appear. This dialog provides also choice of gid lines for Conductivity or Inphase scale.

View Files

This option allows to review data les saved in Allegro.

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.).

Description of Options and Parameters:

EM38/2 Mode (EM38-MK2 Mode)

This option allows you to select the type of instrument survey mode. Set the EM38MK2 mode of operation by selecting an item from the drop-down list box labeled EM38/2 Mode. Available modes are: Auto and Manual. These modes of operation are described below.

Auto Mode

Readings will be triggered automatically at a specied frequency (see option Readings/s). In Auto Mode only one dipole mode (Vertical or Horizontal) can be selected.

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, Horizontal or Both) can be selected. Please note that when Manual mode is selected options the option Reading/s changes to option labeled Samples/Rdg.

EM38MK2 Data Logging System (DAS70-CX)

Readings/s (Readings per second)

When this option is available (only in Auto mode) activate text box by tapping 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 xed 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 specied frequency of 20 readings/s will result in the effective data acquisition rate of 21 readings/s (every reading is logged), 9 readings/s will cause the 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 specied 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 edit box only accepts 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 le 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.

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)

Tapping 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.

When Manual mode was selected three settings are available: Vertical, Horizontal, and Both (see Figure below).

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If Auto mode was selected then only two dipole modes are available: Vertical or Horizontal (see Figure below).

Survey Line (survey line name)

Activate text box by tapping or using TAB key and then enter desired name (number) for the survey line.

This is a user’s tag number/name for the prole 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 tapping or using TAB key and then enter desired for the survey line increment.

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

Sequence

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

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

EM38MK2 Data Logging System (DAS70-CX)

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.

Direction (geographical direction of surveying along survey line)

Tapping 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.

This parameter indicates the heading of the survey line, and is only used for information purposes.

Start Station (start station of a survey line)

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

This parameter species 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 tapping or using TAB key and then entering the desired value for the station increment.

This parameter species 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 tap 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 le and they will be given as default parameters in the subsequent Survey Setup dialog.

To return to original settings (settings before this dialog was selected) tap 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. Logger Setup

This option allows you to specify several parameters in the logger. The Logger Setup dialog is presented below.

Description of Parameters:

EM38-MK2 Port

Displays the number of serial ports that are assigned to the EM38MK2. Available selections: COM1, COM2, COM3, ... to COM12, with the exception of COM6 that is named as Bluetooth and assigned for Bluetooth communication. Connection of EM38-MK2 and Allegro via Bluetooth is described below in section 3.1. The program default is COM1. Communication parameters for the selected serial port are set by the program, since the EM38-MK2 operates at xed settings: Baud Rate (19200), Parity (N), Data Bits (8), and Bit Stop (1).

This port must be different than the port specied in the Set Port for GPS option (see next chapter), 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).

Units

Two selections are available: Meters or Feet.

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 10 readings/s) the sound may appear not uniform, however this does not affect quality of data acquisition.

EM38MK2 Data Logging System (DAS70-CX)

Pause key

Four selections are available: any key, Space Bar, Enter, and P This feature is used to pause data recording during logging session. Default setting any key can be changed to one of the three specic keys for eld conditions where a logger key can be accidentally pushed causing unwanted stop of data logging.

After all the parameters in the Logger Setup dialog are updated tap 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 le and they will be given as default parameters in the subsequent Logger Setup dialog.

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

3.1 Bluetooth Connection of EM38-MK2 and Allegro CX

Data can be transferred from EM38-MK2 to Allegro CX by a wireless Bluetooth connection. To select Bluetooth connection select Bluetooth item in EM38-MK2 Port list box (Figure below).

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When Bluetooth connection is selected and Logger Setup is closed with OK button and other survey parameters are specied, please proceed and tap (or execute by keyboard) option Monitor/Log. At that time the EM38-MK2 must be ON.

After the button Monitor/Log is tapped the Allegro CX operating system starts detecting all devices transmitting Bluetooth signal. The following window will be displayed.

When the progress bar in the above window ends a list of detected Bluetooth devices will be displayed. In most cases it will only be EM38-MK2, however if any other Bluetooth enabled device is in range (for example cellurar telephone, GPS receiver, etc.) it will also be placed on the list.

EM38MK2 Data Logging System (DAS70-CX)

Please select Geonics EM38-MK2 by tapping the Select button. If Geonics EM38-MK2 is displayed as the only item, the Select button must still be tapped or executed from the keyboard (in most cases this button is highlighted, therefore pressing ENTER on the keyboard is sufcient). At this point the operating system will gather the necessary information from the EM38-MK2 Bluetooth device. No action is required, a windows shown below will be displayed for a few seconds.

After the above window disappears the EM38MK2 screen in Monitoring mode will be displayed and the program can be operated in exactly the same manner as using the standard serial port.

Please note that during Bluetooth connection the instrument cannot be turned OFF. Even a momentary rotation of the switch labeled MODE to the position OFF will result in a connection break and will end the logging mode. A new logging session will have to be started to continue measurements.

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4. Set Port for GPS

After the Set Port for GPS button was tapped (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, specify serial communication parameters matching GPS receiver settings, and to monitor the GPS output in terminal mode (the bottom button). 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 Allegro. In such case data le will contain proper sequence of EM38-MK2 readings without any GPS input.

Tapping 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: Enable and Disable.

Serial Port

The number of serial ports assigned to the GPS input. Available selections: COM1to COM12, with the exception of COM6.The program default is COM2. Communication parameters for the selected serial port can be determined in options described below.

EM38MK2 Data Logging System (DAS70-CX)

This port must be different than the port specied in the Logger Set Up menu (for EM38MK2), otherwise a message will be displayed and ports will have to be reassigned.

Tapping 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.

Port COM6 is named Bluetooth and it is assigned for Bluetooth communication. This type of connection can be used if GPS receiver is equipped with a Bluetooth option. Please refer to GPS receiver manufacturer instructions. The procedure for detecting Bluetooth by the Allegro will be the same as that described in the earlier section 3.1. Only one Bluetooth

connection can be used by the Allegro operation system, therefore if Bluetooth connection is assigned for EM38-MK2 data acquisition the GPS receiver must then use one of the physical serial ports. If Bluetooth communication is selected then all serial

communication parameters described below are ignored by the program since they are adjusted automaticaly by the Allegro operating system.

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, 38400, 57600, and 115200.

Tapping 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.

Tapping 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.

Tapping 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.

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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.

Tapping 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 Set GPS Port dialog are updated tap 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 le 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) tap Cancel (X) button or press Esc key. All parameters will be reset to initial settings and the dialog window will disappear.

To activate terminal mode which allows you to monitor GPS receiver output tap the button labeled Monitor GPS Output, or when using keyboard select this button using TAB key and press ENTER. The monitoring mode will work regardless of the GPS Input being Enabled or Disabled. This op-

tion is described in the following section.

4.1 Monitoring GPS Receiver Output

After the button Monitor GPS Output is tapped or executed by the keyboard the program will display the screen in terminal mode. In this mode the screen is divided into three parts. The largest, top portion of the screen displays the GPS receiver output. The middle portion shows that last NMEA command sent to the GPS receiver (by default command shown in Figure below), and at the bottom three buttons representing available options: Pause/Go, Send, and Exit. These buttons can be tapped, executed by TAB key and ENTER keys, or by using shortcuts (pressing underlined letter keys). This screen is shown below.

As soon as the EM38MK2 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.

EM38MK2 Data Logging System (DAS70-CX)

The message NO DATA is normally updated with a rate of 7 seconds. This may indicate the following: serial port number not correctly specied 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 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 specied 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 tap (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 tapped 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, tap OK button or press the key <ENTER> to send the command to the GPS receiver. Tapping 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 SAT is given in the below gure (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 conrmation message will be send by the

receiver ($PASHR, ACK*3D) and data stream will contain the message SAT ($PASHR, SAT,.....

in the above gure).

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 conguration of these type of receivers can be updated only by the controlling device (usually GPS logger, controller, or the receiver panel keys).

EM38MK2 Data Logging System (DAS70-CX)

5. Display Options

After the Display Options button was tapped (or executed from the keyboard) in the Main Screen the Display Options dialog window appears on the screen. This dialog allows you to enable and disable the display of each channel prole, specify color and thickness of proles, and select grid lines for conductivity or Inphase scale. The dialog is presented below.

Description of Options and Parameters:

Display

Color

To enable or disable displaying of each component, dipole mode, and coil separation prole tap on the corresponding button labeled Display. Proles of all component/dipole mode/coil separation combinations with checked buttons will be displayed during data logging.

Regardless of which components, dipole modes, and coil separations are chosen to be displayed as proles, data for all readings received from the instrument will be displayed in numeric form below prole display.

To change colour of each prole tap the coresponding button (with colour line) labeled Color. The following dialog titled Color will appear.

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

Tap the button OK or press ENTER key to accept the highlighted colour. The Color dialog

EM38MK2 Data Logging System (DAS70-CX)

will disappear and the colour of the appropriate channel button will updated. To cancel colour selection tap Cancel (X) button or press Esc key.

Thickness

Specify thickness of a prole for a desired channel by using one of four drop-down boxes labeled thickness. Thickness of a prole curve is expressed in pixels. Available settings are: 1, 2, 3, or 4 pixels.

Tapping 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 tapping 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.

Grid Lines

Proles 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 gure below where grid lines are plotted for conductivity scale.

After all the parameters in the Display Options dialog are updated tap 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 le 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) tap 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 Monitor/Log button (in Main Screen) is tapped or executed by the keyboard, the program enters logging session which contains three modes: Monitoring, Stand By and Logging. Program starts logging session always in Monitoring mode. In this mode EM38MK2 readings, dipole mode

and GPS parameters can be examined quickly and a data le can be created. After a data le 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 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 an initial inspection of the range of instrument readings at a particular site and the monitoring of 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 will appear:

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:

EM38MK2 Data Logging System (DAS70-CX)

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

Two lines 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: user specied instrument dipole mode (V, H or B following label Mode:), current display mode (Monitor, Stand By or Logging), and Allegro battery level (in % of full charge). When ducial marker is pressed then M is displayed next to label Stn:.

The second, largest graphic section will be used to display proles during the logging of data.

The third section contains two lines of text. The rst line is used to display EM38-MK2 readings and the second line of text provides GPS related information.

The EM38-MK2 readings are labeled C: (conductivity for coil separation 1.0 m), I: (Inphase for coil separation 1.0 m), c: (conductivity for coil separation 0.5 m), i: (Inphase for coil separation 0.5 m). In summary upper case labels correspond to 1.0 m and lower case labels to 0.5 m coil separation. Conductivity is displayed in mS/m and Inphase in ppt. Current dipole mode is displayed in the right top portion of the screen (end of second line) as Ver (Vertical) or Hor (Horizontal). The EM38-MK2 readings are updated approximately 21 times per second during the monitoring session.

When GPS was Disabled in the Set GPS Port dialog a message GPS Input: disabled will be displayed. If the GPS port is Enabled and a working GPS receiver is connected to the eld computer the Monitoring screen will display GPS parameters, as presented below.

In the above Figure one line of the display is dedicated to show the GPS status. A label Pos/# will be used during data acquisition, it will provide the number of GPS positions saved in the data le. In Monitor mode this label indicates GPS activity by toggling between forward (/) and back (\) slash (that follows label Pos) every time the program receives a message from the GPS receiver. If the slash is not changing for long periods of time it means that the GPS receiver is not working or that it is not connected to the eld computer. A label DGPS (Differential Global Positioning System) indicates that GPS readings are differentially corrected in real time, while label AGPS (Autonomous

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Global Positioning System) indicates lack of differential correction. 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 9 (Set Port for GPS), Appendix A, and to GPS manuals for more information about GPS parameters.

The fourth section of the Monitor window lists the program functions available directly in the Monitor mode given at the bottom of the screen in the form of buttons. Available options are as follows: Create File (create data le), Calibrate (Calibrate EM38-MK2), Del Calibr. (Delete Calibration Factors), and Exit (exits the Monitor mode and returns program to Main Screen.

Description of Monitoring Mode Options

Create File (create data le)

When a data le is created the program will switch to Stand By mode automatically. The log le can be created in the given default directory (DATA38MK2) or in any other

directory in the Allegro CX. If other directories are used, please note that only subdirectories of C_Drive represent save, non volatile memory.

The name of the le is given by the eld 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.

The le name can be specied in the Create Data File dialog using the Windows standard interface procedure. The EM38MK2 data les cannot be appended.

Each data le in the eld computer (raw data le) has an extension name N38 and it is created in the directory specied in Create Data File dialog. The N38 les are created in the instrument binary format. They can be viewed using the Main Screen option “View Files”. These les can be also converted to ASCII format and processed in the Geonics DAT38MK2 program.

After the le is specied tap the button OK or press ENTER key to accept and create data le. The program will switch Monitor mode to Stand By mode and the data le will be displayed on the screen.

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

Esc key.

Calibrate (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 how-

EM38MK2 Data Logging System (DAS70-CX)

ever here all the procedure is controlled by the program EM38MK2. During Calibration the program calculates proper factors for conductivity and Inphase at each coil separation and dipole mode. These values are saved in the Allegro CX memory as long as option (Del 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 efcient and easy to perform

3) all calibration factors are saved in Allegro memory and are written in data le 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 le.

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

After the instrument is placed on the monopod in Vertical dipole mode tap button Yes or press key Y (or Enter if button is highlighted). After button Yes was tapped 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 GPS parameters.

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

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.

The program monitors instrument orientation and as soon as it detects that the EM38MK2 is in proper position it will display the following message "Preparing for Horizontal

Calibration" and after a small delay required for stabilization the Horizontal Calibration will be performed.

EM38MK2 Data Logging System (DAS70-CX)

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

conrmation message will be displayed.

After beep the above message disappears and program returns to normal operation. All calibration factors are saved in Allegro CX 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 Del Calibration.

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

Del Calibr. (Delete Calibration factors)

After tapping Del Calibr. button (or executing this option using keyboard) the program immediately displays conrmation message:

Please conrm 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 Allegro 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 tapping 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 data le is created in Monitoring mode the program automatically switches logging window to Stand By mode. This windows is similar to Monitor mode however it contains survey parameters (le 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 in initial state (before any data is recorded) is presented below.

The main portion of the screen is occupied by the plot area which displays proles (see Figure below which shows Stand By mode after some data were collected). There are two scales within the plot area. Scale for conductivity is labeled at the top and bottom of the plot window, and labels for Inphase are placed inside (under and over labels for conductivity). The amplitude scale is divided by four or ve 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 are shown in numeric form below the plot area. Values of readings are labeled C, I, c, and i and displayed in the following order (from the left): conductivity for coil separation 1.0 m, Inphase for coil separation 1.0 m, conductivity for coil separation 0.5 m , and Inphase for coil separation 0.5 m. Dipole mode (Vertical or Horizontal) of the current reading is displayed above the plot area, at the right side of the screen as label Ver (vertical dipole mode ) or Hor (horizontal dipole mode). EM38-MK2 readings (in numeric form) are updated in Stand By mode approximately 21 times per second. Proles in the plot area are updated only during Logging mode when data are actually saved in the data le.

EM38MK2 Data Logging System (DAS70-CX)

A section of the window at the top of the screen contains two lines of text displaying survey and instrument related parameters. These are (from top left): current data le name (labeled File:), survey mode (Auto, Wheel or Manual), user selected instrument mode dipole mode V (vertical),

H (horizontal), or Both (only in Manual mode) labeled Mode:, logging mode Stand By or Logging), Allegro internal battery level (in % of full charge, not labeled), current survey line (labeled Ln:), current station (labeled Stn:). When ducial marker is active a label M is displayed between

station label and station value. Label Ver or Hor in the right end of the second line displays dipole mode of the current reading.

In the Stand By mode the station number will not change. Stations in the EM38MK2 program are incremented by station increment value after each reading is written to the data le.

One line of the display is dedicated to showing the GPS status. A number following the label Pos/# provides the number of GPS positions saved in the current data le. In Stand By mode the number of positions is not incremented (it is updated only when GPS position is written to the le). However this label indicates GPS activity by toggling between forward (/) and back (\) slash (that follows label Pos) every time the program receives a message from GPS receiver. If the slash is not changing for long periods of time (larger than GPS receiver update rate) it means that the GPS receiver is not working or that it is not connected to the eld computer. 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. 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.

Several available eld options are listed at the bottom (in form of buttons) 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 tapping on the GO button 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 in the mode correspond- ing 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 Pos) in the data le is incremented every time (usually once a second) GPS position is written to the le. Prole curves (for channels selected in Display Options window) are updated after each reading is written to the data le.

There is only one option available in the Logging mode - pause logging. After a Pause button is tapped 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 21 readings per second, however data will not be saved in the log le and prole curves will be not updated.

Exit from the logging session and access to eld options are available only from the logging window in Stand By mode.

6.4 Stand By Mode Field Options

Several eld options are available while the Logging window is in the Stand By mode. More frequently used options can be accessed directly from command buttons and others can be used from pop up menu activated by button Menu (displayed below). Command buttons can be used by tapping 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.

Options listed in the menu can be accessed directly (without displaying pop up menu from Menu button) by using keyboard shortcuts, i.e. pressing key S will display Scale dialog. While menu is displayed options can be selected by tapping on the appropriate proper option, or from the keyboard by pressing the shortcut keys or by navigating using <Up> and <Down> arrow keys and executing by <ENTER>

GO (start data logging)

Tap 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.

EM38MK2 Data Logging System (DAS70-CX)

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 specied in the Survey Setup menu.

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 tap 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 (Ln:) name and current station (Stn:) value will be updated and prole 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) tap Cancel (X) button or press Esc key, the dialog window will disappear.

NStn (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.

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.

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Tap 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 (Stn:) value will be updated and after data logging is activated the prole curves will have a small gap (two pixels) showing the new station entry (see Figure below).

To return to Stand By mode and current survey line settings (state before this dialog was selected) tap 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.

Tap 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 le 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 tap Cancel (X) button or press Esc key, the dialog window will disappear and measurements can be continued.

EM38MK2 Data Logging System (DAS70-CX)

Scale (New Scale for Prole Plot)

Selecting New Scale option allows the operator to enter new scale parameters for the prole plot for each component. This option is available only from pop up menu (accessible from Menu button) or directly from keyboard by using shortcut key <S>.

The Enter Scale dialog will be displayed. It contains four text boxes for Minimum and Maximum values of a new scale for prole 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. Outer numbers indicate scale for conductivity and inner 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 specied tap the button OK or press ENTER key to accept new values and the prole plot area will be redrawn (see Figure below).

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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.

Display Options (new options for prole plot display)

This option is available only from pop up menu (accessible from Menu button) or directly from keyboard by using shortcut key <D>.

After the Display Options item was selected in the pop up menu the Display Options dialog window appears on the screen. This dialog allows you to enable and disable the display of each channel prole, and specify color and thickness of proles. The dialog is presented below.

Please refer to chapter 5 where this dialog and its parameters are described in detail. Tap the button OK or press ENTER key to accept updated display parameters. The dialog

will disappear and prole 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)

tap 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.

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 le and displayed readings will be adjusted immediately after the Calibration procedure is completed.

EM38MK2 Data Logging System (DAS70-CX)

Delete Calibration (remove calibration factors)

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

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

Exit (exit data logging)

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

After above message is conrmed the program stops logging, closes data le and returns to Main Screen.

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7. View Data Files

This option allows you to view recorded data les. After the View Files button is tapped (or executed from the keyboard) in the Main Screen the View Data Files window will be displayed. A current

display scales (minimum and maximum value for Conductivity and Inphase) is given by two labels located at the top center of the screen (i.e. C: 0/500 means conductivity scale from 0 to 500 mS/m). Range of scale display for both components can be changed by tapping the button labeled Scale.

To open the data le tap the button labeled File or execute this option using the keyboard (navigate to the button by pressing TAB key and when highlighted press ENTER key, or use shortcut - press key F). The Open Data File dialog is presented below.

The le name can be selected in the Open Data File dialog using the Windows standard interface procedure. After the le is selected (highlighted) tap the button OK or press ENTER key to accept and display data le (to cancel selection tap Cancel (X) button or press Esc key). After the le is opened readings taken at the beginning of the rst survey line in the le are displayed, as shown below.

EM38MK2 Data Logging System (DAS70-CX)

Name of the currently displayed data le is shown in the left top corner of the window. The main portion of the screen is occupied by the plot area which displays proles. The display range (minimum and maximum values for Conductivity and Inphase) is given by two labels located at the top of the screen, above plot window. For example, label C: 0/500 means conductivity scale from 0 to 500 mS/m and I:-10/20 means Inphase scale ranges from -10 to 20 ppt. Ranges of scale display can be changed by tapping the button labeled Scale. The plot area is divided by four or ve grey grid lines. In cases where the amplitude scale starts with a negative value, then the grid line corresponding to zero is always plotted as a thicker line. Grey grid lines are associated with a scale displayed with bold font.

A vertical bar (grey vertical line) indicates currently displayed station. The station is displayed above the plot area, next to label Stn: and readings at this station for channels conductivity and Inphase are shown in numeric form (8 elds) below the plot area. Component, dipole mode, and coil separation labels are not displayed due to the small screen of the Allegro. Eight values of readings are displayed in the following order (from the left): conductivity/vertical/1.0 m, conductivity/horizontal/1.0 m, Inphase/vertical/1.0 m, Inphase/horizontal/1.0 m, onductivity/vertical/0.5 m, conductivity/ horizontal/0.5 m, Inphase/vertical/0.5 m, and Inphase/horizontal/0.5 m. In other words, rst four values represent coil separation of 1.0 m and following values show readings for separation 0.5 m. EM38MK2 readings (in numeric form) are updated every time vertical bar is moved. If label xxxxx is displayed in numeric eld it means that there is no reading for respective dipole mode (it is most common situation that Vertical or Horizontal readings are displayed at given station, only data taken in manual mode can result in display of all 8 values at one station)

To change the currently displayed survey line use the drop-down box labeled Line located in the top right corner of the window. Tapping on the down arrow next to the text box labeled Line opens a

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drop-down box showing the available survey lines. When the keyboard is being used you can activate the text box by pressing the TAB key until the drop down box is highlighted and then by using Up or Down arrow keys select one of available lines (as shown below).

To shift the range of the displayed stations and to move the vertical bar indicating the currently displayed station, use the buttons located along the bottom of the View Files window. These buttons can be activated by tapping or by pressing the keyboard keys. A help screen containing info related to each button can be displayed at any time by tapping (or executing from keyboard) the Help button labeled ?. The Help screen is shown below.

When moving displayed prole along survey line:

button labeled <<-- or key Home moves display to the start of the currently displayed survey line, the left most station is the start station of the line,

button labeled -->> or key End moves display to the end of the currently displayed survey line, the right most station is a nal station of the survey line,

button labeled <--- or key PgUp moves display 80 stations to the left, button labeled ---> or key PgDn moves display 80 stations to the right.

When changing stations and corresponding readings:

button labeled |<-- or key Left (left arrow) moves vertical bar (station) one station to the left,

button labeled -->} or key Right (right arrow) moves vertical bar (station) one station to the right.

Range of scale display for both components can be changed by tapping the button labeled Scale. The Enter Scale dialog (shown below) will be displayed. It contains four text boxes for Minimum

EM38MK2 Data Logging System (DAS70-CX)

and Maximum values of a new scale for prole plot of conductivity and Inphase. Values displayed in bold indicate the scale that is associated with grey grid lines (specied earlier in Diplay Options dialog).

After minimum and maximum values are specied tap the button OK or press ENTER key to accept new values and the prole 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.

To exit the View Files window tap the button labeled Exit (or from keyboard use shortcut key X or press key ENTER when the button is highlighted) to close le (if open). The program will return to Main Screen.

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Appendix A

A.1 Description of Data File in EM38MK2 Allegro CX Format

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

Header of the le (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

M 3 8 V 1 0 UT0 ID IM 10

H File Name Time/Samples 10

K 2

EM38MK2 - identication of program le 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

IM - EM38MK2 survey mode (0 =Auto, 2 =Manual) IC - not used CS - instrument type File Name - le name, maximum 8 characters Time/Samples - this eld depends on EM38MK2 survey mode Auto Mode - Time Increment in seconds Manual Mode - Samples/Reading 10 - Line Feed character

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

Survey Type

( 0 - xed)

( 1 = EM38-MK2-1, 2 = EM38-MK2-2)

23 24IC25 26

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 211022

23 24

25 26

Line Name (8 characters)

B Start Station (Format F11.2) 10

Dir

Z D D M M Y Y Y Y H H : M M : S S 10

O Calibration for Q/P 1.0 m (F10.3) 101 Former Cal. for Q/P 1.0 m (F10.3)

O Calibration for Q/P 0.5 m (F10.3) 102 Former Cal. for Q/P 0.5 m (F10.3)

O Calibration for I/P V 1.0 m (F10.3) 103 Former Cal. for I/P V 1.0 m (F10.3)

O Calibration for I/P V 0.5 m (F10.3) 104 Former Cal. for I/P V 0.5 m (F10.3)

O Calibration for I/P H 1.0 m (F10.3) 105 Former Cal. for I/P H 1.0 m (F10.3)

O Calibration for I/P H 0.5 m (F10.3) 106 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)

EM38MK2 Data Logging System (DAS70-CX)

Station Increment (Format F11.2) 10

EM38MK2 Data Logging System (DAS70-CX)

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)

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 le 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

Gn 3l3h2l2h 4h 5h 5l 6h Time Stamp in ms (10 digits)4l

1h 1l

Time Stamp in ms (10 digits)

I - indicator T, t, or 2 T - rst reading at the EM38-MK2-2 station (default for Auto mode) t - rst 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 Decimal Value and Meaning

7 6 5 4 3 2

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

128

64 32 16

8 4

0 not used 0 not used 0 not used 0 not used 0 not used Marker = 1 trigger pressed = 0 otherwise Mode = 1 Vertical = 0 Horizontal 0 not used

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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 the following formula 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 or Inphase) = (Channel x 5 / 1024 - 160) x 8

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

Comment (maximum 11 characters)

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

New Station (Format 11.2)

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. 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.

Time Stamp in ms (10 digits)

EM38MK2 Data Logging System (DAS70-CX)

O Calibration for Q/P 1.0 m (F10.3) 101 Former Cal. for Q/P 1.0 m (F10.3)

O Calibration for Q/P 0.5 m (F10.3) 102 Former Cal. for Q/P 0.5 m (F10.3)

O Calibration for I/P V 1.0 m (F10.3) 103 Former Cal. for I/P V 1.0 m (F10.3)

O Calibration for I/P V 0.5 m (F10.3) 104 Former Cal. for I/P V 0.5 m (F10.3)

O Calibration for I/P H 1.0 m (F10.3) 105 Former Cal. for I/P H 1.0 m (F10.3)

O Calibration for I/P H 0.5 m (F10.3) 106 Former Cal. for I/P H 0.5 m (F10.3)

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 le 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 rst 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 EM38MK2 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

23 24

$ ,AGG h m m s s . s s ,h d d m

G P

x , M , sxs s ,

mmm

, , d d d m m . ms m m m

p p . p , s a a, a a a

a CRcc* LF

a a

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 denition of each component of GGA data message.

. +,u, x x x .

a a

m q,n, q

Time Stamp in milliseconds

, s

. m

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A.2 Example of Data File in EM38MK2 (Allegro CX) Format

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

EM38MK2 W115GPS00002 H 090916A 0.100 L0 B 0.00 AS 1.000 Z09092007 16:49:17 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 ’@БEяяƒ£ЫЫ 40165321 T … ¿AяяvƒЫЫ 40165416 @$GPGGA,223956.00,4336.59 #316,N,07936.65071,W,2,4, #3,134.93,M,-35,M,4,118*5 #C ! 40165402 T ‡vБ}яя~еЫЫ 40165511 @$GPGSA,A,3,,,,,,28,,17,1 #1,08,,,09.3,02.7,08.8*09 # ! 40165484 T ”гАаяя……ЫЫ 40165606 T ‰ЫГ яя «ЫЫ 40165700 T ¤(а яя¤WЫЫ 40165795 T •чЫсяяŽ£ЫЫ 40165890 T †/Аlяя‚ЫЫ 40165985 T †!¿ яя~4ЫЫ 40166080 T ˆ%Бояя„’ЫЫ 40166175 T ”Бияя3ОЫЫ 40166270 T Š Вуяя…<ЫЫ 40166365 T ¯ бхяя ЫЫ 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 ŠЖ‘яя…‚ЫЫ 40166555 T …иИяя‚tЫЫ 40166650 T †„ƒяя ¯ЫЫ 40166745 T ‡яБеяяa ЫЫ 40166839 T ’2Б~яя„TЫЫ 40166934 T ®ŽЭˆяяŸьЫЫ 40167124 T † БZяя3ВЫЫ 40167219 T †ю¿мяяƒЫЫ 40167314 T †ž¿¸яя~²ЫЫ 40167409 @$GPGGA,223958.00,4336.59 #312,N,07936.65069,W,2,4, #3,135.25,M,-35,M,5,118*5 #2 ! 40167401

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

EM38MK2 Data Logging System (DAS70-CX)

Appendix B

B.1 Using the EM38MK2 with a GPS Receiver

The EM38MK2 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 EM38MK2. 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 EM38-MK2. Normally, the EM38MK2 running in Allegro CX 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 EM38MK2 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 EM38MK2 dedicates one line of the display to show GPS status. A label DGPS (Differential Global Positioning System) that GPS readings are differentially corrected in real time Label AGPS (Autonomous Global Positioning System) indicates lack of differential correction. On the right side of the POS a label a slash character is displayed. This slash alternates between forward and back slash with the frequency of GPS update rate (usually 1 second intervals). If the slash is not moving for longer period of time it means that GPS system is not working or that it is not connected to the eld computer. Number of recorded GPS positions are displayed on the right side of the alternating slash following # sign. This number is updated only in the logging mode, when the data are recorded. (In Stand By mode or during Monitoring only the alternating slash, and updated values of PDOP and number of tracked satellites, indicate presence of GPS input).

Two more GPS parameters are displayed on the logger screen. These are index PDOP shown by label PDOP and number of tracked satellites represented by label Sat. The index called PDOP (Position Dilution of Precision) 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.

EM38MK2 Data Logging System (DAS70-CX)

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>

Denition of GGA message component:

hhmmss.ss UTC time in hours, minutes, seconds of the GPS position ddmm.mmmmm 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 s=E or s=W, for East and West longitude n Quality indicator, 0 = no position, 1 = raw, no differentially corrected

position, 2 = differentially corrected position, 9 = position computed using almanac information

qq Number of satellites used in position computation pp.p HDOP = 0.0 to 99.9 saaaaa.aa Antenna altitude u Altitude units, M=meters +xxxx.x Geoidal separation (requires geoidal height option) M Geoidal separation units, M = meters sss Age of differential corrections in seconds aaaa Base station identication *cc Checksum <CR><LF> Carriage return and Line feed

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>

Denition of GSA message components:

c1 Mode, M = manual, A = automatic d1 Mode, 2 = 2D, 3 = 3D d2-d13 Satellites used in position computation (range 0 to 32) f1 PDOP (range 0 to 99.9) f2 HDOP (range 0 to 99.9) f3 VDOP (range 0 to 99.9) *cc Checksum <CR><LF> Carriage return and Line Feed

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Geonics Limited EM38-MK2 Operating Instructions Manual

Specifications and Main Features

Frequently Asked Questions

User Manual