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	Title      Andfjorden-2014      RV "HÅKON MOSBY"
	By O.M.	Date 13 September 2014	Version 0.1

Open photo album to see similar instrument layout on OBS-2014 survey.

RV "HÅKON MOSBY" - CONTACT INFORMATION

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VESSEL INFORMATION

CONTACT INFORMATION

Click to visit webpage describing RV "Håkon Mosby"

Phone (via satellite): (+47) 5590 6420 (+47) 5590 6423 (Bridge) Mobile (bridge): (+47) 9770 1413 Call sign: LJIT To reach the vessel via VHF radio, call either Bodø or Vardø coast radio station and ask for RV "Håkon Mosby", stating vessel call sign LJIT. Vardø coast radio covers Barents Sea and the coastal areas from the Kola peninsula to Tromsø. Current position: http://www.sailwx.info/shiptrack/shipposition.phtml?call=LJIT If AIS coverage: http://www.marinetraffic.com/ais/default.aspx?mmsi=258244000

RECORDING LOG SHEET

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• Recording log sheet

TIME STAMPING OF SHOT EVENTS

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The Ocean Bottom Seismographs that are deployed on the sea floor, or recorders on land, keep time using very accurate internal clocks, or GPS.

It is necessary to obtain time stamp of every shot event in order to process data later on. The time stamping is done by routing the "SCOPE TIME BREAK" from GUNCO signal to a GPS based event recorder.

The "SCOPE TIME BREAK" signal is emitted on "Zero time" - the nominal firing moment of all guns, according to the timing method that has been selected from GUNCO menus. It is emitted in sequence after two GUNCO input control signals have been asserted correctly - the CLOSURE and FIRE signal. The relationship between these three signals is shown below.

So the falling edge of the SCOPE TIME BREAK signal is used as input for the time stamping unit.

1. Antenna is still mounted adjacent to the life boat.
2. Primary time stamping system, Ashtech ProFlex Lite DG14, is documented here.
3. Back-up time stamping system is documented here.
4. Time stamp signal used: GUNCO, BNC connector on rear panel labelled: "FTB SCOPE" (FTB = "Field Time Break"). Signal level is TTL (ca 0-5V), active low with leading, falling edge indicating Time Break (=shotpoint time).
5. Ashtech GPS records shot events in GPS time which is currently 16 seconds ahead of UTC time. Ref.: http://en.wikipedia.org/wiki/Leap_second and http://leapsecond.com/java/gpsclock.htm

GRAVITY METER

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Synchronizing SPRING TENSION values

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Remember to synchronize SPRING TENSION value in software with the actual spring tension as shown on the counter on the left side of the sensor platform.

Daily log

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Log sheets can be downloaded from this page: http://www.geo.uib.no/eworkshop/gravitymeter/index.php?n=Main.LogSheets

Sensor installed in vessel

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1. Remove all cushioning material used to prevent the sensor cradle from moving. At least three places.
2. When sensor is clamped (the knurled knob turned fully clock wise) adjust the front panel meter if it's not showing ZERO.
3. Switch on sensor by depressing two MCBs = Miniature Circuit Breakers on the power supply box, which is located behind the sensor platform (access to the right side).
4. Perform a BEAM ZERO AND GAIN test as described on page xx of the manual. We are using L&R sensor.
5. Start Gravity PC in instrument room. Software path: C:\ULTRASYS\ultrasys.exe

Beam Zero and Gain adjustment (L&R Sensor)

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Refer to gravity meter manual.

K-check

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Refer to gravity meter manual.

Base readings; land gravity meter

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1. The two Gravity base readings we performed on OBS survey in July/August is documented here.
2. Land gravity meter is always connected to battery so the sensor temperature is kept constant at 49.5 degC. While inactive, the battery is connected to charger which is powered from 230 Vac.
3. Ensure that 230Vac cable to charger is well protected from edges of the lid. Some cushioning material should prevent the lid from closing and thus severing the cable (fuses in vessel will then blow also).
4. You must first adjust rotating wheel so it shows values which will be expected in Tromsø - around 6018. It was last used in Longyearbyen where vaules are around 6422. Rotate the wheel gently to avoid "upsetting" the gear mechanism.
5. Base reading procedure:
   1. Sensor readings should be stable. TC (Total Correction) as shown on screen should be around zero.
   2. First: "Still Reading" => Write down the six fields in the sensor record shown on the computer screen: [1] Time (consisting of Day_of_year + time UTC, [2] Digital gravity, [3] Spring tension, [4] CC = cross coupling, [5] Raw = beam position, [6] TC = total correction
   3. Disconnect gravity meter from 230Vac charger. All connectors are polarized and labelled - can't go wrong. Move land gravity meter to quay beside ship. Measure distance from quay to water table surface with rope that's inside the gravity meter box. Remember to bring a tape measure. Level the meter. Unclamp the beam screw. Take three measurements, always adjusting the wheel so values are increasing. You can either look at meter, or use the ocular. Clamp the meter afterwards.
   4. Move to reference point and make three recordings.
   5. Back to same location at quay and make three new recordings.
   6. Make a new Still Reading.
   7. Reconnect gravity meter to 230Vac charger. Remember the cushioning material under the lid of the case.

GUN CONTROLLER "GUNCO"

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GUNCO connector wiring

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The key to understand the GUNCO connector system is to see how the front slot positions of the MSIBG cards corresponds to the connectors on the rear side - see figure below.

We normally only use one MSIBG card located in slot #5. This card will thus have sensors connected on SI3 (labelled "STBD1,2"), and solenoids on SO5 (labelled "STBD 1").

GUNCO rack wiring (rear view)

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Current system

Click to open PDF document:

Old system

The difference is that relays have been added for the airgun solenoid test unit, which allows the operator to monitor sensor voltage and current, and measure resistance to solenoid.

GUNCO Sensor Display

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This is what a GUNCO sensor display could look like. Click to see larger version. NOTE: Airgun no. 1,2 and 6 is OK. No. 5 has crossfeed from the solenoid pulse; the "crosfree blanking" feature of the GUNCO is activated (red area), causing any signal that appears within the read zones to be ignored.

MINI-STREAMER RECORDING SYSTEM

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We will use a two-channel mini-streamer, and record data on a Geometrics GEODE, which is controlled from a PC laptop running Windows.

• Manufacturer: Geometrics
• GEODE manual

SYNC UNIT

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The Sync Unit is placed between the EIVA Survey computer and GUNCO. It receives a trigger command from the survey computer in the form of an ASCII "A" sent over RS232 serial line.

The Sync Unit was designed in 1998 and at that time also interfaced two other systems, a magnetometer and a recording system (DFS V) that have both been phased out long time ago. The LCD menu hasn't been updated and thus still provides options that reflects those now unused systems (so don't get confused).

At that time the Survey Computer by mistake sometimes issued double shot event triggers a couple of seconds after the proper trigger. This caused the GUNCO to fire when it wasn't supposed to. To prevent this situation the Sync Unit was furnished with a software timer that defined a period in which new triggers were ignored after the first one. The green LED on the front panel is lit during this "trigger ignored" interval.

This survey requires 12.5 meter shot point distance, which means the "trigger ignored" setting must be reduced from it's current value of approx 8 seconds, down to 1 second. This is explained in section below.

Front view - click to enlarge.

Inside view - click to enlarge.

Rear view - click to enlarge.

Routing of CLOSURE and FIRE signal to GUNCO

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The GUNCO is now controlled by the "Triacq" recording system of the 3km streamer. Two BNC cables must be relocated so it will become slave to the Sync Unit instead:

1. Disconnect the coax cable bundle (consisting of three cables) from the Triacq recording system. The Triacq recording is located in rack #3 counting from GUNCO. Remove the rear wooden "door" in the corridor.
2. Route like this:

     ---------------------------
     SYNC UNIT           GUNCO
     ---------------------------
      CLOSURE   <---->   CLOSURE
      FIRE      <---->   FIRE
                         FTB  (not needed)
                         FTB SCOPE (to GEODE recording, GPS time stamp unit)
   

Schematics

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• Schematics, Sync unit interface
• Schematics, Sync unit wiring
• Schematics, Magnetometer interface unit (not used anymore).

CPU card inside: "Flashlite-V25"

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The CPU card is "Flashlite-V25" made by JK Micro. This product has long since been replaced by other versions. The documentation cannot be located (here's a report from someone using it in 2000). But it's quite similar to its replacement, Flashlite 186:

• Flashlite 186 data sheet (PDF)
• Flashlite 186 manual (PDF)

How to alter the "trigger ignored" time parameter

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The Flashlite 186 CPU card is in reality a tiny MSDOS computer. In initial mode we get contact with the card via serial RS232 cable. A terminal program will then get access to the normal DOS prompt.

A user program is automatically started by following instructions found on page 2 of the Flashlite 186 manual:

When power is applied to the Flashlite or when it is reset, the board goes through its initialization procedure and then starts DOS. A simple (read-only) AUTOEXEC.BAT file is executed and then the board is ready to use. The batch file performs several functions before the user is given control. The DOS search path is set, the DOS prompt is set, the CTRL-C flag (discussed later in this manual) is checked and finally, an attempt is made to execute a file named STARTUP on the B: drive. This provides a convenient way for custom applications to execute immediately after initialization of the Flashlite. If you wish to have your application start automatically, create a batch file named STARTUP.BAT that invokes the program.

Here is the crucial point. The program accepts command line parameters. The first parameter instructs the card to operate in either "OBS" mode (that we use now) or "DFS" mode (which is deprecated). And the second parameter sets the "trigger ignored" duration, in seconds.

So in the STARTUP.BAT file the last line will be the program name followed by two parameters, "OBS" and "8" (or close to that figure). The last parameter must be set to "1" instead. If it's omitted the program uses a default value of 15 seconds instead.

How can the STARTUP.BAT file be edited? First the program that is running on the CPU card must be terminated or prevented from starting. That can be done in two ways:

1. Connect a RS232 serial cable (1-to-1) between laptop and 25-pin female DSUB connector at the rear of the Sync Unit. Start a terminal program on laptop (TeraTerm or HyperTerm). Comm parameters are: 9600 8N1. This is what is referred to as the CONSOLE input in the Flashlite manual.
2. Prevent the program from starting by entering <CTRL>+<C> after resetting or powering the unit (there is a reset switch on the top, or use the rear rocker switch). After interrupting the normal start-up sequence the CONSOLE port should now issue a DOS prompt.
3. ALTERNATIVELY: Quit a running program by sending a <Q> or <ESC> character. Important: This command must be sent on the other serial port - the one that is connected to the Eiva Survey Computer and normally only receives the trigger character <A>. After that switch to the CONSOLE serial port. Press <ENTER> to see that DOS prompt is returned. This port is 25-pin DSUB male. It is probably wired as DTE (Data Terminal Equipment) with output on pin 2 (which will be pin 3 if measured on a 25-to-9 pin adapter). So a null modem cable or -adapter is needed.

The edit process itself is described on page 15 of the Flashlite 186 manual:

EDIT.COM
A simple line editor is included to allow quick creation and modification of batch files or other text files. EDIT is similar to Microsoft’s EDLIN provided in earlier versions of MS-DOS. It allows list, insert, delete, and modify. Upon exit, a backup of the original file is created (filename.BAK) and the edits are saved. If a backup file with the same name already exists, it is overwritten. A list of commands and their usage is available by entering ‘h’ at the edit prompt ( >> ). The name of the file to edit must be supplied following the command EDIT on the command line.

 EXAMPLE:
  B:\>edit test.bat
  FlashLite Line Editor v1.0
  Enter h for help
  New File: test.bat
  >> i
  0: @echo Batch file being processed...
  1: mytsr
  2: myapp
  3: ^Z
  >> l
  0: @echo Batch file being processed...
  1: mytsr
  -> 2: myapp
  >> q
  Save before exit (Y,n): y
  File Saved
  B:\>

Here is a description of the vintage MSDOS EDLIN command line editor.