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Geometrics G-864 User Manual

Cesium backpack magnetometer and cesium backpack gradiometer
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User Manual
for
G-864 Cesium Backpack Magnetometer
and
G-864G Cesium Backpack Gradiometer
P/N 770-00105-01 Rev. A2
January 2023
COPYRIGHT © 2023

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Summary of Contents for Geometrics G-864

  • Page 1 User Manual G-864 Cesium Backpack Magnetometer G-864G Cesium Backpack Gradiometer P/N 770-00105-01 Rev. A2 January 2023 COPYRIGHT © 2023...
  • Page 2 PH: (408) 954-0522 FAX: (408) 954-0902 We declare under our sole responsibility that our marine magnetometers, models G-864 and to which this declaration relates are in conformity with the following standards: EN 55022: 1995, EN50082-2 : 1995, ENV 50140: 1994, ENV 50141 : 1994, EN 61000-4-2: 1995, EN 61000-4-4: 1995...
  • Page 3 Warning This is a Class A product. In a domestic environment this product may cause radio interference in which case the user may be required to take adequate measures.

  • Page 4: Table Of Contents

    Table of Contents ..........7 Geometrics’ G-864 Cesium Backpack Magnetometer Sensor Performance ......................... 7 Environmental Considerations ....................8 Vibration ............................... 8 1.1.1 Temperature ............................8 1.1.2 ....................9 Unpacking the G-864 System Inventory ........................9 Battery Options ........................11 Getac Tablet ..........................12 Data Logger Box Components ....................
  • Page 5 Equatorial Zone ..........................47 ....................48 Troubleshooting Table ................51 Firmware and Software Updates Geometrics Survey Manager ......................51 Geometrics G-864 Embedded ......................51 Geometrics MagNav ........................52 ....................54 Surveying Principles Guidelines for Small Ground Magnetometer Surveys ..............54...
  • Page 6 Number of People ........................... 54 Survey Efficiency ..........................54 Layout of the Survey Track ......................55 Diurnal Correction .......................... 56 Survey Accuracy ..........................56 Survey Credibility ........................... 57 Location of Small Objects within Associated Anomalies ............. 57 ............59 G-864 Backpack Magnetometer Specifications...

  • Page 7: Geometrics' G-864 Cesium Backpack Magnetometer

    Geometrics’ G-864 Cesium Backpack Magnetometer Geometrics, Inc. is known worldwide for our total field magnetometers and is a leader in magnetometer development. Our magnetic sensors measure the total magnetic field (total field) without directional information. In other words, they take the scalar measurements of the magnetic field, and produce a value that is the magnetic field intensity, regardless of the direction in which the field propagates.

  • Page 8: Environmental Considerations

    1.1.2 Temperature The G-864 system is designed to operate over an ambient temperature range of -35 to +50°C. In an enclosed region it may be necessary to provide adequate cooling by free-flowing air. If the sensor and electronics are in an unconfined region, convection cooling is generally adequate.

  • Page 9: Unpacking The G-864

    3ft. (1m) cable, to fit onto the backpack without snagging branches or other obstructions. For near surface investigations, the G-864 is configured with either one or two sensors (for the gradiometer configuration) and mounted onto an aluminum staff assembly that is positioned out in front of the surveyor.
  • Page 10 G-862 CESIUM ELECTRONICS & SENSOR 900-00342-39 none W/9 FOOT CABLE G-864 DATA-LOGGER TO MAG 7.5FT 840-00095-02 none none CABLE, SINGLE MAG G-864, 2 MAG GRADIOMETER MAG TO 840-00207-01 none none DATALOGGER CABLE 820-00123-01 LOCKING SENSOR STAFF B 820-00127-01 LOCKING STAFF JOINING KIT...

  • Page 11: Battery Options

    Battery Options The G-864 offers two battery options, Lead Acid or Lithium Polymer (Li-Po). The batteries shipped with the system will be the batteries requested at the time of order. Lead acid batteries have traditionally been used in our backpack systems. The Li-Po battery was designed to offer a more lightweight, longer lasting battery solution to customers.

  • Page 12: Getac Tablet

    Getac Tablet The G-864 uses a Getac ZX70 Android tablet as the main data logging, and user interface device. This model is a ruggedized tablet that has been modified to reduce the magnetic characteristics of the tablet for a clean survey. One of the main modifications is the removal of the speaker components, which are very magnetic.

  • Page 13: Recessed Power Button

    2.1.2 Reset Button The reset button is located at the top of the box and used if the G-864 processor is not responding. A reset will not fully turn off the magnetometer, so the sensors do not need to be warmed up again.

  • Page 14: Heat Sink

    There is a heat sink on the backpack to allow heat generated from the internal electronics to dissipate and avoid overheating inside the box. It is important to keep this heat sink clean and intact. If wear and tear is observed on the heat sink, please contact Geometrics to evaluate if it needs to be replaced.
  • Page 15 3. Remove the Velcro Release Tool and insert it between the shoulder harness and the pack frame, breaking loose the Velcro. 4. Move the shoulder harness section up and down to correctly position the height of the shoulder pads.

  • Page 16: Mounting And Connecting The Battery

    Mounting and Connecting the GPS The G-864 comes with a non-magnetic Tallysman GPS. This specific antenna was chosen for its non-magnetic properties which allows the GPS to be mounted within 1ft. of the sensor and not interfere with the magnetic measurements.

  • Page 17: Backpack Mounted Sensor Configuration

    1. To mount the GPS, line up the open slit on the GPS antenna with the black knob on the aluminum staff on the backpack and tighten the knob. 2. Wrap excess cable around the aluminum staff or bunch at the bottom of the backpack to protect the cable from getting snagged during a survey.
  • Page 18 2. On the backpack, loosen the lower knob securing the aluminum staff section and lift it from the bottom support. 3. Line up the open holes on the electronics clamps with the aluminum staff while re- inserting the section into the bottom support on the pack frame. Tighten the black knob securing the aluminum staff into the bottom support.
  • Page 19 4. Secure the electronics clamps to hold the electronics bottle in place by first tightening the bolt lock closest to the aluminum staff section, and then tightening the other bolt lock to secure the sensor in place. 5. At the top of the same aluminum staff section, mount the sensor clamp, securing it to the staff with the bolt lock.

  • Page 20: Staff Mounted Sensor Configuration: Single Sensor

    8. It may be necessary to adjust the sensor orientation for the requirements of the survey location. Please see section below: Sensor Orientation and Adjustments. Staff Mounted Sensor Configuration: Single Sensor Magnetometers with 9ft sensor-to-electronics cables are required for the staff mounted sensor configuration.
  • Page 21 1. To mount the sensor and electronics onto the staff assembly, first place two electronics clamps onto the electronics bottle, keeping the clamps loosely fitted (like Step 1 above). 2. Attach the sensor electronics bottle to a bare aluminum staff section, by loosening the bolt locks on the electronics clamps enough to fit the staff section through.
  • Page 22 4. Then attach another a bare aluminum staff section and tighten the bolt lock.
  • Page 23 5. Connect the sensor clamp to the aluminum staff section containing the black strap. Start by removing the bolt lock from the sensor clamp as shown below. 6. Line up the holes on the sensor clamp and aluminum staff section. Replace the bolt lock. 7.
  • Page 24 8. Place the sensor in the sensor clamp. Tighten the bolt lock closest to the sensor to hold the sensor in place. Avoid overtightening as the sensor clamp can crack if too much pressure is applied. 9. To the backmost staff section holding the electronics, connect the strap hanger - a small aluminum staff piece with a loop.
  • Page 25 10. Clip the end of the long black strap to the strap hanger. 12. Place the white strap clamp onto the aluminum staff section on the backpack and tighten the bolt lock to secure in place.
  • Page 26 13. Connect the sensor data cable to the sensor electronics bottle and to the connector on the data logger box labeled MAG. Rotate the cable connector until the keys align and use the outer ring to secure the connection. Extra cable can be tied to the staff assembly using cable tie-wraps.

  • Page 27: Staff Mounted Sensor Configuration: Gradiometer

    17. It may be necessary to adjust the orientation of the sensor to the requirements of the survey location. Please see the section below: Sensor Orientation and Adjustments. Staff Mounted Sensor Configuration: Gradiometer Only systems with two magnetometers and the 9ft sensor-to-electronics cables are suitable for the gradiometer staff mounted sensor configuration.
  • Page 28 3. Next, attach the aluminum staff section with the foam grip, and tighten the bolt lock (like Step 3 above). 4. Attach a bare aluminum staff section to the section with the foam grip (as in Step 4 above). Tighten the bolt lock. 5.
  • Page 29 10. Place the white strap clamp onto the aluminum staff section on the backpack and tighten the bolt lock (like Step 11 above). 11. Connect the gradiometer data WYE cable to both electronics bottles and to the connector on the data logger box labeled MAG. Rotate the cable to align the keys and use the outer ring to secure the connection.
  • Page 30 Sensor Orientation and Adjustments The sensor may be mounted vertically, at 45º to the vertical, or horizontally. Once the proper orientation is selected for a specific area, it will always mount in that same manner when surveying in the same area. In the far northern and southern latitudes, the sensor will be mounted at 45º;...

  • Page 31: Survey Manager

    Survey Manager Survey Manager is a simple program for managing G-864 Projects, creating Surveys with set parameters, creating Route Files, and converting data files. Survey Manager will routinely be updated.

  • Page 32: Managing Projects In Survey Manager

    On the Survey Manager main page, select G-864, and there will be two options - New G-864 Project and Open Existing G-864 Project. Please review the descriptions of each item in Survey Manager below.
  • Page 33 GPS data. However, GPS will not be synched to 1PPS signal. Base Station: This field is used when the magnetometer being used is a stationary base station magnetometer, such as Geometrics model G-862RBS Base Station. For the use of the G-864, this can be ignored.

  • Page 34: Converting Survey Data Files In Survey Manager

    1. Move Project files from the tablet to the PC library using a USB or data transfer cable. 2. Open Survey Manager, select G-864, select Open Existing G-864 Project. 3. Select the G-864 Project file to convert from the PC library. A list of Surveys will appear in Survey Manager.

  • Page 35: Magnav User Interface Software

    MagNav will be preloaded onto the Getac tablet shipped with the system. If for any reason the software gets uninstalled, the latest version can be downloaded from Geometrics website here, https://www.geometrics.com/product/g-864-magnetometer/, under Downloads. If any assistance is needed, please contact support@geometrics.com.

  • Page 36: Creating New Projects In Magnav

    1. Turn on the tablet and open MagNav. 2. On the Projects page, select Create New Project. 3. Select G-864, enter a Project Name, and click OK. 4. On the Projects Page, select the newly created Project. 5. Select Create New Survey.
  • Page 37 2. Push the Power Button on the backpack to turn it on. The LEDs will perform a series of flashes indicating the system is warming up. a. Blue POWER LED should remain solid; White PPS LED should flash once per second, Orange GPS LED should flash once per second, Green MAG LED should flash 10 times per second, Red USB LED will flash momentarily and then will remain off.

  • Page 38: Surveying With Marked Navigation In Magnav

    pointer indicates direction of travel. If the Swath Radius was chosen carefully, good coverage of an area can be attained by painting the area solid green. c. The Heat Map tab is where color contour magnetic field maps will be created after some data has been collected.

  • Page 39: Correcting Mistakes

    a. When a mark is selected, the text in the lower right corner will show the course over ground according to the GPS, the bearing (or direction to the mark), and the distance to the next mark. 6. When you approach the last mark in the line, the “MARK” button will change to “END LINE.

  • Page 40: Deleting A Project In Magnav

    2. A popup will appear in the top right. Select Delete Project. 3. Press OK when asked to confirm. MagMap & MagPick Geometrics offers free software for processing magnetic data, MagMap and MagPick. These can be downloaded from the Geometrics website, https://www.geometrics.com/software/. Import Collected Data to MagMap After finishing the survey and the data has been moved to the computer with Survey Manager and MagMap installed it is time to load the data into MagMap for data processing.
  • Page 41 If using a base station, remember to have the base station file open when ready to export the data from MagMap to ensure that the data is diurnally corrected. For more information about data processing in MagMap or MagPick, please consult the manuals for those programs on our website at www.geometrics.com/software, or contact MagSales@geometrics.com.

  • Page 42: Csaz

    “AZ” stands for azimuth or inclination. The program is located on the Geometrics USB drive included with the G-864. Please read the manual that is imbedded within the program for complete instructions on how to use the program for sensor orientation solutions NOTE: at various locations on the globe.
  • Page 43 Unless the sensor is quite near very magnetic objects, the local magnetic field will be almost entirely due to the earth’s magnetic field. Therefore, in latitudes where the inclination of the earth’s field vector is 45º, vertical orientation of the sensor’s axis will allow operation in all practical survey orientations.
  • Page 44 In addition to the diagrams provided here, the program CsAz may be used to calculate the sensor’s output for a particular orientation for the magnetic field attitude in the survey area. This is a DOS program and is provided on the Magnetometer Support USB supplied with the magnetometer.

  • Page 45: Mid-Latitude Zone

    Mid-latitude Zone The diagram to the left shows the recommended sensor orientation for operation in mid latitudes. This zone is shown as the shaded regions above and includes those areas where absolute inclination of the Earth’s magnetic field is greater or equal to 20º and less than or equal to 75º.

  • Page 46: Polar Zones

    Polar Zones The diagram to the left shows the recommended sensor orientation for operation in polar latitudes. This zone is shown as the shaded regions above and includes those areas where the absolute inclination of the Earth’s magnetic field is greater or equal to 65º.

  • Page 47: Equatorial Zone

    Equatorial Zone The diagram to the left shows the recommended sensor orientation for operation in equatorial latitudes. This zone is shown as the shaded region above and includes those areas where the absolute inclination of the Earth’s magnetic field is less than or equal to 25º.

  • Page 48: Troubleshooting Table

    Long warm-up time. Adjust heater to 34.5 K-ohms: contact factory Low heater setting. for details. Defective internal sensor or Return sensor and electronics to Geometrics electronic components. for repair. Locate and eliminate sources of noise or Local field is noisy.
  • Page 49 Preventing a problem is almost always less costly than correcting the problem. We recommend checking the following items as part of any new installation or whenever an existing installation is altered. It is also recommended that these items are checked periodically as part of a scheduled platform or system safety check.
  • Page 50 6. Larmor amplitude check and adjustment (Authorized Repair Facility only) a. Potentiometer on sensor-driver board adjusted for 2.0 Volts Peak to Peak at 50,000 nT after 20 minute warm up 7. Heater check and adjustment (Authorized Repair Facility only)

  • Page 51: Firmware And Software Updates

    Verify that the correct version has been installed. Geometrics G-864 Embedded 1. Take the USB drive from the top of the G-864 backpack (from under the black environmental cover) and insert it into the PC. 2. Run the installer – Setup-G864-Embedded-3.1.1812-750.exe r.

  • Page 52: Geometrics Magnav

    USB is removed without using “eject”, the program update on the USB drive may be corrupted. w. Insert the USB drive into the socket in the top of the G-864 backpack and turn on the power. During this process the new software will be installed into the backpack, and the database in the USB drive will be initialized.
  • Page 53 b. Press and hold the app icon, and then drag the icon a little while still pressing. c. The folder will disappear, and Android will allow dragging of the app to a place on the desktop. 6. Start the app. Go to the Status page and verify that the version is correct.

  • Page 54: Surveying Principles

    Surveying Principles This section outlines the principles of performing a magnetic survey for anomaly location. It covers setting up, performing the survey and location of items of interest within anomalous zones. Regional or geologic surveys for mineral exploration require a different set of procedures and are not covered in this overview.

  • Page 55: Layout Of The Survey Track

    confusion, the immediate correction of errors, and using fail-safe procedures. All the methods suggested below are simple, low tech, and relatively slow, but proven effective. They can easily be improved but at the risk of greater time, poorer survey quality or greater cost. So, in the beginning, keep it as simple as possible.

  • Page 56: Diurnal Correction

    Note that the high measurement rate of the G-864 allows a rapid walking speed along the profile line. Thus, even large target anomalies are covered within tens of seconds, reducing the potential Diurnal effects.

  • Page 57: Survey Credibility

    anomaly’s shape, its peak-to-peak amplitude, and its true location. Large changes in speed along the profile line will have a similar effect but can be prevented using intermediate waypoints. (The worst-case condition would be “off line” by +20% in one direction and "off line”...
  • Page 58 Viewing this profile on the G-864 display will allow the estimation of the point of inflection of the curve between the peaks indicating the point of maximum Gradient (which should be directly over the object), and the depth of burial by means of the half width rule.

  • Page 59: G-864 Backpack Magnetometer Specifications

    G-864 Backpack Magnetometer Specifications MAGNETOMETER Operating Principle: Self-oscillating split-beam Cesium Vapor (non-radioactive). Operating Range: 20,000 to 100,000 nT. Operating Zones: The earth’s field vector should be at an angle greater than 10° from the sensor’s equator and greater than 10° from the sensor’s long axis.
  • Page 60 Warranty: 2 Years on magnetometer, 3 Years on Getac ZX70 tablet (register with Getac). Standard Accessories: Backpack, staff assembly, sensor and electronics clamps, GPS receiver, 2 batteries and charger, Getac tablet and charger, tablet chest harness, power/data cable, USB Drive for backpack system updates, Geometrics USB drive with software and manuals, shipping/storage case(s).

This manual is also suitable for:

G-864g

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