LaCoste & Romberg LLC
The first name in gravity since 1939

MODEL U UNDERWATER GRAVITY METER MANUAL

CHAPTER 4

SYSTEM CONTROLLER

The Underwater Gravity System ( abbreviated "UGS" ) software uses an IBM-compatible personal computer to control most aspects of data acquisition. The personal computer can be supplied by LaCoste and Romberg with the underwater gravity meter if ordered as an option. If you supply your own computer, be sure to check the computer hardware requirements listed under the System Description chapter. A basic knowledge of the MS-DOS operating system will be required for simple tasks such as formatting disks and copying files.

SOFTWARE INSTALLATION

The UGS software package is delivered on one floppy disk containing all the necessary files. Before using the software, a backup copy of the original disk should be made. Put the original disk in a safe place and use the copy for normal operations. Check that your delivery disk contains the files listed here:

Although UGS will operate from a floppy disk drive, many program functions perform better when a hard disk drive is used. If using a hard disk, we suggest creating a subdirectory labeled \UGS on the hard disk and copying the delivery floppy files into that directory.

Before starting the program, change the default directory to the directory where the UGS files were installed. At the DOS prompt type UGS and press return. The UGS program will execute and display the LaCoste and Romberg Logo and copyright notice. Press any key to continue.

The two main windows ( TELEMETRY and COMMAND ) will appear on the screen. The system is now waiting for you to select a command from the command menu.

WINDOWS

UGS communicates with the user through a text-oriented windowing system. UGS receives commands from the user and displays information to the user through these windows, which appear and disappear as needed.

The eleven UGS WINDOWS display information as follows:

Telemetry Window

DISPLAYS

There are two special displays which are not formally part of the windowing system. These displays are initiated by the GRAVITY and MANUAL commands, and are as follows:

GRAVITY MODE DISPLAY

The Gravity Mode Display is activated when the user selects the GRAVITY command from the main menu. This is the mode used for normal data acquisition and recording. The Gravity Mode screen is divided into 3 areas, as illustrated below. These 3 areas are the "slider" windows on the left, the "trace" windows on the right, and "control" window on the lower right.

Gravity Mode Display

SLIDER WINDOWS

The "slider" windows area contains four vertical windows. Inside each window are dashed reference lines and the signal input (a solid line that slides up and down, hence the name sliders). The four slider windows are:

TRACE WINDOWS

The trace windows are four horizontal displays that plot both level positions, the cheat voltage, and tide-corrected gravity against time. Each window has a title bar, shows the current numeric value of the signal, and indicates the range of the window. The traces start at the left edge of the window and plot to the right. They wrap back around to the left edge after reaching the right side. Also, the trace will be reset to the middle of the window should it cross the top or bottom limit of the window. The middle of each window is the zero reference point for each signal. The numeric range shown is plus or minus from the zero reference point. The four trace windows are:

CONTROL WINDOW

The control window is located beneath the trace windows. This window displays current meter counter position, an abbreviated list of commands, and the status of the gravity acquisition process.

The five possible gravity modes (indicated as the current status) are :

The available commands in the control window are described in detail in the COMMAND DESCRIPTIONS section under GRAVITY MODE COMMANDS.

MANUAL MODE DISPLAY

The Manual Mode Display is similar to the Gravity Mode Display, except the trace windows area is replaced by a scrolling strip chart displaying the filtered beam position. The strip chart display is activated ONLY if the MANUAL DISPLAY SCREEN switch is changed from ANALOG to STRIP CHART using the EDIT, SWITCH_PARAM command sequence prior to selecting manual mode. The strip chart display is useful for making checks and adjustments to the system, or if you wish to read the meter without the Electrostatic Feedback or Automatic Levelling processes activated.

Manual Mode Display

COMMAND MENUS

Commands are selected from the UGS command menus. The COMMAND WINDOW contains three lines of information about the CURRENT command menu. Line one shows the path from the top of the command menu down to the current highlighted command. Line two shows the current level of commands, and one command will be highlighted. Line three shows either a description of the highlighted command, or the next level of commands if available. A command can be selected from the CURRENT menu level by moving the left or right cursor keys to highlight the desired command. If the command menu contains either the left or right cursor keys, then depressing either shift key while pressing the cursor keys will highlight the desired command. Commands may be selected from the menu by pressing the FIRST CHARACTER of the command. Alternatively, press the RETURN key to go forward one level of commands or the ESC key to go back one level of commands. Any part of the UGS program that is entered from the command menus can be exited from by pressing the ESC key.

COMMAND TREE DIAGRAM

Command Tree

COMMAND DESCRIPTIONS

FILE COMMANDS

(F)iles (L)oad (M)eter_Param
Loads the UGS.PRM file which contains all the meter dependent parameters and calibration tables. This binary format file is loaded automatically upon starting the program.

(F)iles (L)oad (G)ravity_Param
Loads the UGS.GRV file containing the parameters that control gravity data sampling and recording to disk. This binary format file is loaded automatically upon starting the program.

(F)iles (L)oad (C)onfigration
Loads the UGS.CFG file which contains the default gravity data format, window locations and colors, and parallel, serial port assignments. This binary format file is loaded automatically upon starting the program.

(F)iles (L)oad (F)ac_Table
Loads the UGS.CAL file which contains the gravity meter calibration factors unique to the meter sensor. This ASCII format file is loaded, converted to binary, and stored into the UGS.PRM file.

(F)iles (L)oad (V)oltage_Table
Loads the UGS.CHT file which contains the cheat voltage versus milligals calibration table unique to each meter and system electronics. This ASCII format file is loaded, converted to binary, and stored into the UGS.PRM file.

(F)iles (L)oad (D)epth_Table
Loads the UGS.DTH file which contains the depth gauge calibration table unique to each depth gauge. This ASCII format file is loaded, converted to binary, and stored into the UGS.PRM file.

(F)iles (S)ave (M)eter_Param
Saves the current meter parameters into the file UGS.PRM. The previous meter parameters file will be overwritten if present. This file cannot be created from within the UGS program.

(F)iles (S)ave (G)ravity_Param
Saves the current gravity parameters into the file UGS.GRV. The previous gravity parameters file will be overwritten if present.

(F)iles (S)ave (C)onfiguration
Saves the current system configuration into the file UGS.CFG. The previous system configuration file will be overwritten if present.

(F)iles (P)rint (G)ravity_File
Outputs the gravity records contained in a gravity data file to the printer.

(F)iles (P)rint (M)eter_Param
Outputs the current value of the meter parameters to the printer.

(F)iles (V)iew
Displays the contents of a gravity data file and allows editing of selected data fields.

(F)iles (D)irectory
Displays a directory of a specified disk and path. See your MS-DOS manual for the valid format of paths.

(F)iles (C)onvert
Loads a binary format gravity data file, converts the data to ASCII format, and stores the data into another user-specified file.

EDIT COMMANDS

(E)dit (M)eter_Param
Allows editing any of the meter parameters.

(E)dit (G)ravity_Param
Allows editing any of the gravity parameters.

(E)dit (S)witch_Param
Allows editing any of the switch parameters.

(E)dit (C)onfiguration (D)ata_Format
Allows editing of the gravity data format used for creating new data files.

(E)dit (C)onfiguration (L)ocation
Allows editing of the location of any window on the computer display.

(E)dit (C)onfiguration (C)olor
Allows selection of the color of any window. The number of colors available is dependent on the video adapter and monitor in use.

(E)dit (C)onfiguration (P)ort_Param
Allows editing of the ports used for input and output over the serial and parallel ports.

MANUAL MODE COMMANDS

(M)ANUAL
Initiates the MANUAL control mode, which allows the user to manually control the cross and long levels, meter counter reading, beam position, and electrostatic feedback. The switch parameter MANUAL DISPLAY MODE controls what type of display accompanies the command menu. With the switch set to Analog, the normal TELEMETRY window is shown. With the switch set to Strip Chart, a scrolling strip chart is displayed showing the filtered beam position. The MANUAL mode commands are displayed whenever the main menu command MANUAL is executed. Control of the gravity meter is through the MANUAL MODE commands which are :

If the MANUAL DISPLAY MODE is set to ANALOG, the following additional fields of information are displayed in the COMMAND window to tell the status of command actions.

 

GRAVITY MODE COMMANDS

(G)RAVITY
The GRAVITY command initiates the normal gravity data acquisition mode with automated sampling, display, and recording as desired. The GRAVITY mode has a special command menu similar to the MANUAL mode commands described above, plus special commands for gravity recording. The gravity mode commands are :

Three additional fields of information are displayed along with the above commands to show the status of command actions. Fields 1 and 2 function just like they do under the manual command menu.

  1. (Tweak Counter) or (Slew Counter)
    (Tweak Gimbals) or (Slew Gimbals)
    (Cheating Off) or (Cheating Up / Down)
    The status field displays the current operating mode, i.e. monitoring or recording.

OTHER COMMANDS

FILES AND SWITCHES

The various parameters which control system operation are stored in various software files. The files which can be modified by the user are divided into four groups. Three of these groups are stored as disk files, while the fourth group of parameters called software switches are stored in memory.

EDITING FILE AND SWITCH PARAMETERS

The values in any of the above files can be changed using the (E)DIT command and then stored in the disk files using the (F)ILESè(S)AVE command functions. When using an edit command, the parameters are displayed in two columns showing parameter name and contents. The highlighted parameter name is the current parameter which edit commands will change. Edit the current parameter field as follows:

METER PARAMETER FILE

The Meter Parameters file can be examined and any values modified by using the EDIT, METER_PARAMS command sequence. This will cause the following display to appear on the computer:

Edit Meter Parameters

GRAVITY PARAMETERS FILES

The Gravity Parameters file can be examined and any value modified by using the EDIT, GRAV_PARAMS command sequence. This will cause the following display to appear on the computer screen:

CONFIGURATION FILE

The various functions controlled by the Configuration file are divided into four groups:

(D)ATA_FORMAT

Data Format

(C)OLOR

Color

(L)OCATION

Location

(P)ORT_PARAM

Port Parameters

The communication and printer port values are established only during program startup. Any changes to these values will not take effect until they are saved and the program is restarted.

SOFTWARE SWITCHES

The above switches can be examined and changed using the (E)DIT, (S)WITCH_PARAM command sequence, which will cause the following display to appear on the screen:

Switches

GRAVITY DATA FILES

After a data sample is collected, The following RESULTS display will appear on the computer screen:

Results

The user can then press "W" (for write) which will cause that data to be added to the GRAVITY DATA FILE currently specified in the GRAVITY PARAMETERS file. The actual data to be recorded can be controlled by the user with the command sequence EDIT, CONFIG, DATA_FORMAT as described previously under the CONFIGURATION FILE information.

To examine the contents of the GRAVITY DATA file, enter the command sequence FILES, VIEW and enter the correct file name if the default name is not correct. Press RETURN and the following display will appear:

Gravity Data

You can now examine different records throughout the file by using the up and down arrow keys. You can also can edit the station name, the reading, or the comments by pressing "E".

After the GRAVITY DATA file has been collected, the data can be converted to an ASCII format so that the data can be accessed by other software the user may have. The command sequence FILES, CONVERT will cause the following display to appear:

Convert Data

The converted file will have the same name as the original binary file except the extension will be changed to ASC. You can change the name if desired, then press RETURN to start the data conversion.

GRAVITY RECORDING

The following is the general sequence for recording gravity data.

  1. Edit the GRAVITY PARAMETERS file (i.e. the station name and reading number) to the desired values while moving to the next station.
  2. Lower meter to ocean bottom. Watch the depth indicator to see when the meter is on the bottom. If a warning window displays a message that the platform is tilted too much, raise the meter and find a new location where the message does not reappear.
  3. Unclamp the beam arrestment. This will start automatic leveling (unless disabled) of the meter gimbals.
  4. Select the GRAVITY command, which will bring up the gravity display and begin operation in the default monitoring mode.
  5. While monitoring the telemetered gravity data, move the counter and cheat the beam up or down as necessary until the beam stays within the range indicated by the horizontal lines on the beam slider window on the left.
  6. After the cheat voltage has stabilized and a relatively flat gravity trace is displayed, start a sampling and averaging cycle by pressing A. Repeated pressing of A before the cycle completes will restart the cycle. When the cycle finishes, the average gravity value and RMS error are calculated and displayed on the computer screen.
  7. You can now press R to toggle the results screen on and off the display as desired.
  8. If the data are acceptable, press W to write the gravity data record to the disk. After writing to disk is complete the operating mode will return to monitoring.
  9. Press A or M to begin an averaging or monitoring cycle again.
  10. Repeat steps 6 thru 9 until all desired readings at the station are complete.
  11. Exit the GRAVITY mode by pressing ESC.
  12. Clamp the beam arrestment.
    Raise the meter from the ocean bottom.

MULTITASKING

The multitasking capability of the system allows many tasks to be performed simultaneously. Each task operates independently, but is able to communicate with other tasks to share the system resources.

The 15 tasks performed by the system are:

DIGITAL ENCODER INITIALIZATION

In order for UGS to track movements of the measuring screw counter located on the gravity meter, a digital shaft encoder is utilized. This encoder has a resolution of 1 part in 1024. One revolution of this encoder corresponds to one revolution of the measuring screw counter. Whenever power has been disconnected from the underwater meter electronics, the digital encoder must be initialized to establish a zero reference point. The WARNING window will appear to notify the user if this is necessary. Initialize the encoder by executing the (I)NIT, (E)NCODER command sequence from the main command menu.

DIGITAL STATUS INFORMATION

The switch parameter DIGITAL STATUS allows viewing of various hardware status conditions. This parameter can be changed using the command sequence EDIT, SWITCH_PARAM. When this switch is ON the DIGITAL STATUS window will be displayed, and show the following:

C U C C L L R R R R T F H V F L
1 0 0 0 0 0 0 0 0 0 0 0 1 0 1 0

P:456 I:1 IDX:0

Each character in the above list refers to a particular function as indicated in the table below. A value of 1 indicates the switch is closed or activated, and zero indicates an open or deactivated status.

Switch

Use

C

beam arrestment is clamped

U

beam arrestment is unclamped

C

cross gimbal low limit

C

cross gimbal high limit

L

long gimbal low limit

L

long gimbal high limit

R

reserved for future use

R

reserved for future use

R

reserved for future use

R

reserved for future use

T

platform tilt detection

F

outer sphere flood detection

H

heater cycle on or off

V

valid meter command

F

automatic feedback enabled

L

reading lamp on or off

Description of digital encoder information:

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