3t/5t “tripod” obs · 7 revision history.....33 2 issue b. operator's guide 1 introduction...
TRANSCRIPT
3T/5T “Tripod” OBS
Operator's Guide
Part No. MAN-OBS-0004
Designed and manufactured byGüralp Systems Limited3 Midas House, Calleva ParkAldermaston RG7 8EAEngland
Proprietary Notice: The information in this manual is proprietary to Güralp Systems Limited and may not be copied or distributed outside the approved recipient's organisation without the approval of Güralp Systems Limited. Güralp Systems Limited shall not be liable for technical or editorial errors or omissions made herein, nor for incidental or consequential damages resulting from the furnishing, performance, or usage of this material.
Issue B 2010-10-11
3T/5T Tripod OBS
Table of Contents
1 Introduction..............................................................................................................3
2 Internal arrangement...............................................................................................42.1 Functional block diagram................................................................................102.2 Component identification...............................................................................11
3 Operation................................................................................................................133.1 Warnings..........................................................................................................133.2 Testing..............................................................................................................13
3.2.1 Connecting................................................................................................133.2.2 Unlocking and levelling...........................................................................173.2.3 Calibrating................................................................................................193.2.4 Re-locking.................................................................................................19
3.3 Deployment......................................................................................................193.4 Operation.........................................................................................................203.5 Recovery...........................................................................................................21
4 Sample output........................................................................................................224.1 Deployment......................................................................................................224.2 Centring...........................................................................................................264.3 Recovery...........................................................................................................27
5 Connector pin-out...................................................................................................315.1 Instrument connector (Harris variant)............................................................31
6 Specifications.........................................................................................................32
7 Revision history......................................................................................................33
2 Issue B
Operator's Guide
1 IntroductionThe 3T/5T “Tripod” OBS is a combined seismometer and accelerometer in a custom-designed titanium case, suitable for deployment on the ocean bottom at depths of up to 3,000 metres.
The seismometer component is based on Güralp Systems Ltd's industry-leading CMG-3T weak-motion very-broadband force-feedback instruments. Three uniaxial sensor components are mounted orthogonally in separate gimbals, each with individual levelling control systems.
The accelerometer component is based on the CMG-5T compact strong motion instrument and also uses a true-orthogonal force-feedback system.
The 3T/5T Tripod includes a high-quality six-channel digitiser module with full 24-bit resolution, capable of multiple concurrent data rates up to 1000 samples per second. Also in the case is a CMG-EAM embedded acquisition module, which deploys a powerful Linux processor to handle all communications and data storage requirements. The CMG-EAM's convenient web-based and command-line interfaces provide full control and monitoring of the system. A built-in digital signal generator allows the instrument to self-calibrate on request.
The whole system is packaged in a strong, welded titanium case designed for optimal coupling to the sea-bed. The three conically-tipped feet apply the entire weight of the instrument to a very small area, digging deeply into any gravel or silt in order to provide the best isolation from water-borne signals as well as superb conduction of seismic signals from the ocean bottom to the sensor components.
The case-top features a waterproof Subconn BH12M connector for the instrument's power supply and Ethernet communications. Other options are available, including wet-mateable connectors.
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3T/5T Tripod OBS
2 Internal arrangementThe outer casing of the 3T/5T “Tripod” OBS has three protruding feet, giving the instrument its name:
Each foot contains a receptacle for a 3T sensor gimbal. The gimbals are prevented from rotating about a vertical axis by a brass pin, visible in the right-hand picture below, which engages in a slot machined into the sensor's support sphere:
4 Issue B
Operator's Guide
The three 3T sensors, in their individual gimbals, drop into these receptacles. The photo below shows them mounted on a test frame:
Viewed from above, the anti-rotation pin and slot can just be seen, as on the right in the photo below:
Also visible is the orientation pin, projecting vertically from the top of the gimbal, which engages with the drive mechanism.
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3T/5T Tripod OBS
A large PCB fixes to the base of the casing. It carries three stacks of circuit boards, which provide the feedback electronics for the 3T sensors, as well as the 5T accelerometer and the inclinometer.
detail view of the inclinometer
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Operator's Guide
The complete board is shown in position above. The 5T triaxial accelerometer (top right) has had its casing removed. A detailed plan of the major components at this level is shown in section 2.2 on page 11.
The six support pillars clustered around the central titanium compression pillar serve as a mounting for the gimbal drive-motor deck. This holds the gimbal tilt direction drive motors and sensors - one for each component - and the tilt angle drive motors and sensors - again, one for each component.
The tilt direction motors (black) and positional sensors (blue) can be seen on the top of the drive plate in the photos below:
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3T/5T Tripod OBS
A close-up shows the control electronics and end-stop sensors:
Viewed from below, the black tilt angle motor (with its screw drive) and the blue positional sensor (with its rack-and-pinion) can be seen. The hole in the brass block engages with the gimbal's orientation pin.
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Operator's Guide
The motor deck is mounted on the six support pillars and the digitisation and communications electronics sit above that:
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3T/5T Tripod OBS
2.1 Functional block diagram
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Operator's Guide
2.2 Component identification
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3T/5T Tripod OBS
The previous page indicates the locations of major components on the sensor deck. The illustrations below show the main components of the digitisation and communication electronics deck.
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Operator's Guide
3 Operation
3.1 WarningsThe CMG-3T sensor components are very delicate and will be damaged if moved while unlocked. Always lock the instrument and, ideally, use Scream! to monitor the mass positions to ensure that the system is fully locked before moving it at all.
The CMG 3T/5T Tripod OBS weighs 71kg so lifting it incorrectly can cause serious injury. Personnel should obtain training in handling heavy objects. Always take appropriate precautions and use suitable equipment when transporting the instrument.
3.2 Testing
3.2.1 Connecting
The CMG 3T/5T Tripod OBS has a single, multi-pole connector to carry both power input and Ethernet communications. The pin-out for this connector is given in Section 5.1 on page 31. A suitable test cable can be constructed to allow the instrument to be connected to a 24V DC power supply and an Ethernet switch (or, if suitable cross-overs are incorporated, directly into the Ethernet connector of a PC or laptop).
Each instrument is supplied pre-configured with a static IP address; this address can be found printed on the label on the instrument's lid.
Connect the instrument to the network and power supply and allow a minute or so for the EAM's processor to boot. Start a copy of Scream! on a PC with a non-routed connection to the instrument - i.e. the address of the PC must be on the same subnet as the instrument.
From within Scream!, select Network Control from the Windows menu (or use the short-cut keys + ). In the resulting dialogue, ensure that the My Client tab is selected. Right-click in the Servers area at the
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3T/5T Tripod OBS
top of the dialogue and select Add UDP Server from the resulting menu (or use the short-cut key ).
In the Add a GCF Server dialogue, enter the IP address of the appropriate instrument, followed immediately by the port specifier “:1567”. Click the button and the instrument should appear on the list of servers in the upper part of the window.
Right-click on the server and select GCFPING from the resulting menu (or use the short-cut keys keys + ). After a brief delay, a positive acknowledgement of the GCFPING will be reported. If the GCFPING times out, an error message to that effect will be displayed; In this case, check that the address and port of the newly added server are correct and that the network cables are correctly connected. The instrument will respond to ICMP echo requests so your operating system's ping command can be useful to verify connectivity.
After a few seconds, data blocks will start to appear in the lower left-hand side of the dialogue. Close the Network Control window: the two sensors should appear in the source tree on the left-hand side of Scream!'s main window and individual streams should appear on the right-hand side.
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Operator's Guide
From the main window, select Setup... from the File menu (or use the short-cut keys keys + ) and select the Recording tab from the resulting dialogue. Tick the first three “Auto-record...” options as shown:
Switch to the Files tab and check that the destination for the recorded files (Base Directory) is in a suitable location:
Click the button to dismiss the dialogue then, from Scream's main screen, type + to select all streams:
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3T/5T Tripod OBS
Now type to open a WaveView window:
Leaving Scream! running, open a web browser window and enter the IP address of the instrument into the browser's address bar. You will be prompted for a user-name and password. Use the following credentials to log in:
User-name: rootPassword: rootme
The status screen of the EAM's web interface will be displayed:
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Operator's Guide
3.2.2 Unlocking and levelling
From the left-hand menu of the EAM's web interface, select the 3T sensor from the Control menu. Scroll down the right-hand pane until the Ocean Bottom Systems section is displayed:
Clicking the button in the Deploy section will:
• Level each gimballed bowl, one by one;
• Unlock and then immediately centre one mass, then unlock and centre the others in turn
An annotated sample of the output from this function is given in section 4.1 on page 22.
The sequence of actions carried out by the automatic deployment is normal and correct. If it is ever desirable to carry out these actions in a different sequence, each individual action can be performed using other controls on this page: Levelling can be carried out using the button in the Level section after selecting the required bowl from the drop-down menu; The button in the Unlock OBS Components section will unlock each component in turn; and the button in the Centre OBS Components section will centre each component in turn. An annotated sample of the output from the centring function is given in
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3T/5T Tripod OBS
section 4.2 on page 26. Note that the 5T sensor does not require levelling, centring or locking.
Allow the system to settle for five minutes (or significantly longer if it has recently experienced a large change of temperature), then scroll to the top of the web page:
Click the button in the Query Masses section to view a real-time stream of mass position data:
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Operator's Guide
If any of the mass positions appear significantly offset, return to the previous screen (using the Digitiser... link at the top of the right-hand pane) and click the button in the Centre OBS Components section to re-centre the components. Repeat the monitoring and re-centring as often as required until the instrument is stable.
3.2.3 Calibrating
The instrument can be calibrated using the EAM's web interface or by using Scream!. Each method is fully described in the relevant manual.
• Refer to MAN-SWA-0001 for details of calibration using Scream!
• Refer to MAN-EAM-0001 for details of calibration using the EAM's web interface.
3.2.4 Re-locking
The 3T/5T Tripod OBS system is very delicate and must be locked before it can be moved without risk of damage to the sensitive 3T components. The recovery procedure locks each mass in turn, returns each gimbal to the datum position and sets an internal software flag to prevent the sensors being unlocked again until the gimbals have been re-levelled.
To run the recovery procedure, select the 3T sensor from the Control menu on the left-hand pane of the EAM's web interface. Scroll down the right-hand pane until the Ocean Bottom Systems section is displayed, then click the button in the Recover section.
A sample of the output generated by the recovery function is given in section 4.3 on page 27.
3.3 DeploymentFor best results, the CMG 3T/5T Tripod OBS system should be deployed in a shallow pit on the ocean bed, which should then be back-filled after placement.
Previous, similar projects have obtained good results by burying a large plastic tube (such as a dust-bin [trash-can] with the bottom removed and then back-filling with glass beads, as in the picture below.
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3T/5T Tripod OBS
The instrument should be mechanically aligned and levelled to the best extent possible. Alignment can be achieved using the North indication on the instrument lid and levelling can be monitored using the mechanical inclinometer on the system's lid.
In addition, if the instrument is powered during deployment (not unlocked), the inclinometer outputs (available as streams MC for the East/West axis and MF for the North/South axis) can be monitored using Scream!. For coarse levelling, achieving zero output on each is sufficient. For finer control, the calibration documents for the relevant inclinometer should be consulted.
Similarly, the electronic compass outputs are also available for fine alignment. They are transmitted as a text stream on TCP port 10002 using NMEA-style sentences and can be read using telnet or equivalent software.
Once the instrument is in place, the inclinometer outputs should be monitored to check for drifting while the instrument settles onto the ocean bed. If the drift is significant, mechanical adjustments to its position should be made. This process - monitoring and adjustment - should be repeated until the instrument is stable and level.
In any case, the instrument must be within 15° of its ideal position before initiating the EAM's deployment sequence, as described in section 3.2.2 on page 17.
3.4 OperationComplete details about configuring sample rates, data storage and data transmission protocols are given in the EAM/Platinum manual, MAN-EAM-0001, which should be read in conjunction with this manual. Copies of this manual are available for download from our web site, www.guralp.com.
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Operator's Guide
3.5 RecoveryIf the instrument is to be recovered from the sea-bed, the re-locking procedure, as described in section 3.2.4 on page 19, must be carried out first. This procedure locks each mass in turn, returns each gimbal to the datum position and sets an internal software flag to prevent the sensors being unlocked again until the gimbals have been re-levelled.
Once the sensor masses are locked, the system can be powered down (if desired) and then mechanically recovered.
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3T/5T Tripod OBS
4 Sample output
4.1 DeploymentThe output below is typical of that generated by a deployment triggered using the web interface of the CMG-EAM. Explanatory comments are interspersed.
Home Control → → Digitiser 5791-3T05 Deploy→
Digitiser Control
5791-3T05
Deploy5791 3T0500 CMG-3T Command Mode1 blocks in buffer | 255 blocks freeGuralp Systems Ltd - DM+FW v.106 mgs 14/09/10 (Build 51)
ok_3T05 DEPLOY Deploy System? y/n ? ySOH Power up - ok ADXL Device ID 345 x_ 0.2' ~ y_ 0.1' Bowl okSolution saved 0 629 | Tilt |Rotate| X | Y | 629 0 x_ 0.1' ~ y_ 0.2' SOH Power down SOH Power up - ok ADXL Device ID 345 x_-0.8' ~ y_ 0.7' SOH Power up - ok N/S Lock Mass 0.0mA 128 Switch 49Current max 459.6mA : min 0.0mA SuccessN/S Base Locked Success
805 0 641 128 TiltNull set 641
0 0 0 0 x_-0.8' ~ y_ 0.7' << Bowl Datum x_-0.8' ~ y_ 0.8' < Bowl LevelSolution saved 0 0 Individual Bowls : 1 Levelled 2 Levelled 3 NOT Levelled Z LOCKED N/S LOCKED E/W LOCKED 10 seconds | Tilt |Rotate| X | Y | -1 0 x_-0.9' ~ y_ 0.8' SOH Power down SOH Power up - ok ADXL Device ID 345 x_-0.2' ~ y_ 0.3'
22 Issue B
Check that the masses are locked before continuing
Operator's Guide
Bowl okSolution saved 0 -40 | Tilt |Rotate| X | Y | -40 0 x_-0.3' ~ y_ 0.3' SOH Power down SOH Power up - ok Z UnLock Mass 161.5mA 0 49 73.0mA 0 48 67.3mA 0 47 117.0mA 64 Switch 46Current max 246.7mA : min 0.0mA SuccessZ Centring
-26 -36 OK -1% SuccessSOH Power up - ok N/S UnLock Mass 161.5mA 0 49 78.0mA 0 48 80.0mA 0 47 78.9mA 64 Switch 46Current max 194.7mA : min 25.1mA SuccessN/S Base UnLocking08 154.1mA 14908 104.0mA 14808 101.5mA 14708 91.1mA 14608 86.6mA 14508 79.7mA 144
this sequence continues for some time
08 70.9mA 9208 70.8mA 9108 70.1mA 9008 70.2mA 8908 70.0mA 8800 70.1mA 87Unnipped .....-1 599 69.9mA -1 598 69.4mA -1 597 69.1mA -1 596 69.2mA -1 595 68.8mA -1 594 68.8mA
this sequence continues for some time
-1 432 67.8mA -1 431 67.7mA
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Level bowls as necessary
Unlock Z mass, monitoring both micro-switch and motor current
Repeat for N/S
The 1st column is the micro-switch output, the 2nd the motor current and the 3rd is a time-out counter.
The micro-switch is clear, so we now monitor the sign of the mass position (in the 1st column) until it flips...
3T/5T Tripod OBS
-1 430 67.8mA -1 429 67.8mA -1 428 67.9mA -1 427 67.7mA 0 426SuccessN/S Centring -255 250 -2047 8-255 250 -2047 8-255 250 -2047 8-255 250 -2047 8-255 250 -2047 8 126 250 2031 16 126 250 2031 16 126 250 2031 16 126 250 2031 16 126 250 2031 16 126 250 2031 16 -63 127 -2046 32 -63 127 -2047 32 -63 127 -2047 32 -63 127 -2047 32 -63 127 -2047 32 -63 127 -2047 32 31 63 2032 64 31 63 2032 64 31 63 2032 64 31 63 2032 64 31 63 2032 64 31 63 2031 64 30 60 1948 64 28 56 1804 64 36 80 OK 4% SuccessSOH Power up - ok E/W UnLock Mass 184.2mA 0 49 77.1mA 0 48 76.9mA 0 47 80.6mA 64 Switch 46Current max 240.2mA : min 32.6mA SuccessE/W Base UnLocking08 154.6mA 14908 103.7mA 14808 99.7mA 14708 88.9mA 14608 82.4mA 14508 81.7mA 144
24 Issue B
We are now near centre, so we start to monitor the actual mass position.
The 1st column is the motor speed, the 2nd is the motor pulse duration, the 3rd is the mass position and the last is the degree of control.
Repeat for E/W
There is a pause to allow for settling before a final check is made.
Operator's Guide
08 80.2mA 14308 77.6mA 14208 77.2mA 141
This sequence continues for some time
08 69.8mA 9808 69.5mA 9708 69.6mA 9608 69.1mA 9500 69.5mA 94Unnipped .....-1 599 69.0mA -1 598 68.6mA -1 597 68.8mA -1 596 68.6mA -1 595 68.6mA -1 594 68.9mA
This sequence continues for some time
-1 476 66.6mA -1 475 66.5mA -1 474 66.7mA 0 473SuccessE/W Centring -255 250 -2047 8-255 250 -2047 8-255 250 -2047 8-255 250 -2047 8-255 250 -2047 8-255 250 -2047 8 126 250 2030 16 126 250 2031 16 126 250 2031 16 126 250 2030 16 126 250 2031 16 126 250 2031 16 -63 127 -2047 32 -63 127 -2047 32 -63 127 -2047 32 -63 127 -2047 32 -63 127 -2047 32 -63 127 -2047 32 -63 127 -2047 32 31 63 2031 64 31 63 2031 64 31 63 2031 64
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3T/5T Tripod OBS
31 63 2031 64 31 63 2031 64 31 63 2031 64 31 63 2031 64 31 63 2030 64 30 60 1945 64 28 56 1816 64 4 20 281 60 5 20 308 56 5 20 305 52 5 20 286 48 6 20 272 44 6 20 263 40 6 20 252 39 242 248 OK 11% SuccessSOH Power down 127 seconds ok_3T05 go
Command 'Deploy' run successfully
The process is now complete.
4.2 CentringThe output below is typical of that generated by a centring operation triggered using the web interface of the CMG-EAM. Explanatory comments are interspersed.
Home Control → → Digitiser 5791-3T05 Centre OBS Components→
Digitiser Control
5791-3T05
Centre OBS Components5791 3T0500 CMG-3T Command Mode1 blocks in buffer | 255 blocks freeGuralp Systems Ltd - DM+FW v.106 mgs 14/09/10 (Build 51)
26 Issue B
Near the end of the sequence, there is a pause between each action and the subsequent check, to allow for settling.
Operator's Guide
ok_3T05 CENTREALL SOH Power up - ok Z Centring -41 -48 OK -2% SuccessSOH Power up - ok N/S Centring 125 126 OK 6% SuccessSOH Power up - ok E/W Centring 250 248 OK 12% SuccessSOH Power down 26 seconds ok_3T05 go Command 'Centre OBS Components' run successfully
The process is now complete.
4.3 RecoveryThe output below is typical of that generated by a recoivery operation triggered using the web interface of the CMG-EAM. Explanatory comments are interspersed.
Home Control → → Digitiser 5791-3T05 Recover→
Digitiser Control
5791-3T05
Recover5791 3T0500 CMG-3T Command Mode1 blocks in buffer | 255 blocks free
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Vertical first...
Output in counts and as a %age
Repeat for N/S and E/W...
3T/5T Tripod OBS
Guralp Systems Ltd - DM+FW v.106 mgs 14/09/10 (Build 51) ok_3T05 RECOVER Lock sensors for recovery? y/n ? ySOH Power up - ok SOH Power up - ok Z Lock Mass 159.2mA 0 49 82.8mA 0 48 162.8mA 0 47 314.0mA 128 Switch 46Current max 314.0mA : min 0.0mA SuccessADXL Device ID 345 629 0 629 128 TiltNull set 629 0 0| Tilt |Rotate| X | Y | 0 0 x_ 0.2' ~ y_ 0.1' 7 seconds SOH Power down SOH Power up - ok SOH Power up - ok N/S Lock Mass 159.3mA 0 49 85.3mA 0 48 98.4mA 0 47 85.0mA 0 46 0.0mA 128 Switch 45Current max 197.8mA : min 0.0mA SuccessN/S Base Locking 156.2mA 0 599 72.9mA 0 598 71.9mA 0 597 72.5mA 0 596 73.0mA 0 595 73.1mA 0 594
This sequence continues for some time
74.7mA 0 367 74.6mA 0 366 74.2mA 0 365 74.2mA 0 364 73.1mA 0 363 73.3mA 0 362 73.0mA 0 361 72.8mA 8 Switch 360Current max 193.3mA : min 67.6mA 193.4mA 149 157.3mA 148 156.4mA 147 153.6mA 146 153.9mA 145
28 Issue B
The columns are motor current, switch output and a countdown timer.
The N/S base is driven to the locked position until the micro-switch is activated....
.... and then we change to current monitoring to drive it fully home.
Operator's Guide
This sequence continues for some time
170.3mA 102 176.1mA 101 181.8mA 100 178.9mA 99 193.7mA 98 209.1mA 97Current max 209.1mA : min 153.6mA SuccessADXL Device ID 345 641 0 641 128 TiltNull set 640 0 0| Tilt |Rotate| X | Y | 1 0 x_-0.8' ~ y_ 0.7' 40 seconds SOH Power down SOH Power up - ok SOH Power up - ok E/W Lock Mass 181.2mA 0 49 82.4mA 0 48 95.8mA 0 47 87.6mA 128 Switch 46Current max 225.7mA : min 0.0mA SuccessE/W Base Locking 143.7mA 0 599 63.9mA 0 598 63.6mA 0 597 63.5mA 0 596 64.0mA 0 595 63.8mA 0 594
This sequence continues for some time
68.4mA 0 419 70.4mA 0 418 69.8mA 0 417 67.6mA 0 416 69.0mA 0 415 70.2mA 0 414 69.0mA 8 Switch 413Current max 176.2mA : min 62.7mA 185.4mA 149 155.5mA 148 151.8mA 147 151.3mA 146 151.1mA 145 151.0mA 144
This sequence continues for some time
159.1mA 105
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Repeat for E/W
3T/5T Tripod OBS
168.6mA 104 173.7mA 103 191.1mA 102 192.0mA 101 209.2mA 100Current max 209.2mA : min 139.4mA SuccessADXL Device ID 345 601 0 601 128 TiltNull set 601 0 0| Tilt |Rotate| X | Y | 0 0 x_-0.3' ~ y_ 0.4' 34 seconds SOH Power down ok_3T05 go
Command 'Recover' run successfully
The process is now complete.
30 Issue B
Finally, return the bowls to their datum positions.
Operator's Guide
5 Connector pin-out
5.1 Instrument connector (Harris variant)This is a SubConn BH12M plug,
The mating connector is part number BH12F, manufactured by SubConn and available from Gardner Technologies Inc (www.gardnertechnologiesinc.com), MacArtney Ltd (www.macartney.com), and other suppliers.
Pin Function
1
2
3 Ethernet Tx+ (w.r.t instrument - connect to Rx+ on node)
4 Ethernet Tx- (w.r.t instrument - connect to Rx- on node)
5
6
7 Ethernet Rx+ (w.r.t instrument - connect to Tx+ on node)
8 Ethernet Rx- (w.r.t instrument - connect to Tx- on node)
9
10
11 Power supply +24V DC
12 Power supply ground
Wiring details for the compatible socket, BH12F, as seen from the cable end, i.e. during assembly.
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3T/5T Tripod OBS
6 SpecificationsPhysical
Total weight 71kg
Effective submersed weight 40kg
Electrical
Supply voltage 24 VDC
32 Issue B
Operator's Guide
7 Revision history2010-04-28 A New document2010-10-08 B Added sample output from OBS commands.
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