Innovation and Reliability Since 1980

Quantum V6

Dear Colleague:

Welcome to Quantum, a periodic e-newsletter for professionals working with magnetic technologies. Quantum is designed to keep you up to speed on applications, case histories, and evolutions of quantum magnetometers in a variety of disciplines.

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Case Histories – Win a GEM Golf Shirt for Your Contribution

GEM is seeking case histories from our users regarding magnetometers and their applications to real-world earth science challenges or research projects. Submissions can be very short (two to three paragraphs), preferably with an image of data acquired in the field.

Now is your chance to contribute and inform your fellow earth science professionals about the creative work that you are conducting or interesting projects in which you have been involved.

GEM will enter you in a drawing for a GEM Golf Shirt (1 shirt per newsletter issue). Odds of winning are good, so please consider contacting us at info@gemsys.ca with your submission!

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Customer Service – Update Your Warranty Online for Fast Access to Updates

GEM is pleased to offer the longest warranty in the geophysical instrumentation industry as a demonstration of its confidence in the quality of its products. All GEM products are waranteed to the original purchaser against defective parts and workmanship for two (2) years from the date of original shipping. A summary document of the precise TERMS and CONDITIONS is provided at http://www.gemsys.ca/GEM_warranty_card.htm

As part of its customer service program, GEM recently implemented an Online Maintenance capability for all customers using its magnetometers. Click the link above and you will also see a series of entry fields at the bottom of the form. Simply complete the form and submit and your warranty will be forwarded directly to us.

Then, you will be all ready for any updates that GEM prepares – a timely way to acquire new and upgraded features via the Internet.

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Airborne Magnetometers – GEM Develops Helicopter System

With the increased activity in airborne geophysics, earth science professionals are seeking solutions for acquiring high-quality helicopter airborne data at minimal cost. GEM is pleased to be able to offer such as solution based on its optically pumped Potassium technology.

Main benefits include:

  • Cost effective installation via an integrated set of acquisition components
  • Easy operation using GEM’s proven GSMP-30A acquisition console
  • Elimination of costly data systems with GSMP-30A console
  • Reliable acquisition of high resolution data via the most sensitive commercial airborne magnetometer / gradiometer on the market
  • Accurate positioning of survey measurement locations via integrated radar and GPS data
  • Rapid downloading of results via high-speed RS-232 connection

The system can also be adapted to fixed-wing aircraft. For details on the helicopter system, click here.

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Archaeology – Seen on the Web

The following section provides a short summary of useful / interesting links related to archaeology.

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Earthquake Prediction – GEM Presents Paper at SEG

GEM recently delivered a technical paper at the Society of Exploration Geophysicists’ meeting in Denver. This paper describes the state-of-the-art in (electro) magnetic measurements for earthquake research. Existing methods have met with limited success due to limited sensitivity and long-term stability of instruments; imperfect elimination of environmental noise; and in the case of induction coils, to limited low frequency features and the skin effect for their bandwidth of measurements.

We also analyze dipolar magnetic fields and gradients of magnetic moments generated by earthquakes with emphasis on their strongly local character. The magnetic moments of two measured precursors are calculated as well as the maximum distances at which those earthquakes can be detected with both present methods and a new proposed method (i.e. short base Potassium gradiometer).

Due to the extreme sensitivity of the Potassium SuperGradiometer, the new method is at least one order of magnitude more sensitive than presently used induction coils. SuperGrad features and installations are described. To access your copy of the slides for the presentation, click here.

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Mineral Exploration – Multi-sensor Platforms

Increasingly, explorationists are seeking to use multiple combinations of sensors for performing more complex and comprehensive magnetometer and gradiometer surveys. This demand is based on recognition of a number of factors, including:

  • Platform options – snowmobile, boat, towed cart, hand-operated cart
  • Enhanced resolution – closely spaced data
  • Efficient definition – structural features
  • Augmentation of mapping – sub-vertical contacts
  • Determination of location – off-line magnetic sources
  • Detection and delineation – pipe-like sources
  • Integration – use of multi-parameter surveys

The following image shows one platform used by a major mining company for base metal exploration and detection of pre-existing iron well-heads under a lake.

The system employed 4 sensors recording data to a GSM-19 rover unit. GPS information was recorded separately in this application and then merged.

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Observatories – US Geomagnetism Program

The United States Geological Survey has initiated what is referred to as the USGS Geomagnetism Program. The most important product of this program is a time series record of stable magnetometer data having high accuracy and resolution. These requirements are key reasons that the USGS is upgrading their systems to GEM Overhauser magnetometer (GSM-90 EUROMAG) products.

For a description of how the USGS collects, transports, processes, manages and disseminates magnetic results, select http://geomag.usgs.gov/operations.html. To access a talk that was delivered in Mexico in October 2004 outlining the USGS’ Personal Computer Data Collection Platform, click here.

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UXO Detection – Development of an Integrated System

The multi-sensor unexploded ordnance (UXO) detection system (MUDS) developed by Geophysical Solutions, Inc. simultaneously deploys both the GEM Advanced Magnetometer’s GSMP-40 optically-pumped Potassium vapor magnetometer and the Geonics EM-63 electromagnetic system in very close proximity (1.5 meters) to one another. The system is tracked with the receiver a high precision (sub decimeter) real-time GPS positioning system and all data are monitored with a real-time data acquisition system. Data from the electromagnetic, magnetic, and positioning systems are recorded with a laptop computer in real-time, and available on a visual display as profile data plots, and tracking using a map-type display.

The MUDS was developed by Geophysical Solutions to simultaneously collect geophysical sensor data expressly for the detection of UXO. The MUDS is capable of quickly detecting and precisely locating both surface and subsurface UXO and will increase the safety and efficiency of characterizing UXO contaminated sites. All components can easily be containerized for shipment by standard couriers and rapidly deployed to extremely hazardous sites on an emergency response basis with a minimum of personnel.

The MUDS is equipped with a real-time data visualization and sensor tracking system that incorporates interactive navigation and field survey design capabilities. All geophysical sensor data is collected at essentially the same time and position to increase the probability of discriminating individual UXO targets.

This innovative approach of collecting magnetic and electromagnetic data concurrently at small sensor separation is a significant advancement over other systems currently deployed. The NavCom SF-2050M is currently being deployed to track each sensor and re-acquire anomaly positions. The NavCom receiver uses the StarFire satellite-based augmentation system (SBAS) to obtain sub decimeter accuracies or sub-centimeter accuracies using real-time kinematic corrections.

Field testing of the platform and sensors took place at two locations near Albuquerque, New Mexico, and at the U.S. Army Corps of Engineers UXO test bed in Vicksburg, Mississippi. The instrument platform proved to be robust in these field-scale tests, and the value of multi-sensor datasets was apparent upon analyses of these data.


Figure 1. Multi-sensor UXO Detection System (MUDS).

Figure 2:
The MUDS platform in the field in February 2004.

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Geographic Positioning Systems – Seen on the Web

As part of our service to our customers, GEM regularly performs searches on the Internet to familiarize our clients with the latest developments in magnetics (regardless of Magnetometer supplier). Here are some of our recent results:

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GPS Enhancements – More Value for Your Investment

GPS has become a much-desired and valued capability among magnetometer users. For users operating stationary observation systems, the key value is the GPS time value used to synchronize the magnetometer. For users of mobile magnetometers and gradiometers, position information (in 3D) is also important.

GEM has recently implemented new capabilities designed primarily for mobile magnetometers. Enhancements include:

  • New data values. Altitude and number of satellites are now reported. Altitude is a key value for numerical modeling programs that typically require some kind of an elevation surface (i.e. which can now be recovered directly with the magnetometer). The number of satellites value is ideal for the operator who wants to evaluate the integrity of the satellite network while making measurements.
  • Standard GPS with . This resolution applies to the Space Based Augmentation System (SBAS). SBAS includes the Wide-Area Augmentation System (WAAS), the Eurpoean Geo-Stationary Navigational System (EGNOS) and the MTSAT Satellite based Augmentation System (MSAS).

For operators who are working outside of the SBAS network (i.e. in the far North or South), the resolution for single point readings is 5m (Circular Error of Probability)

  • Centimetre UTM table. GEM’s GPS values are based on WGS-84. The underlying UTM table used to calculate GPS values now adds two extra digits. This alleviates a problem noted when performing “walking” surveys – consecutive measuring stations could have the same value, making interpretation difficult. Now, each station has an additional two digits so that each station is resolved uniquely.

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Magnetometers and Gradiometers – Survey Preparation

The following are short-form notes describing typical issues to consider before carrying out a field survey. They were written by Dr. Francis Jones, University of British Columbia and have been used with permission of the author.

1. Is the Target Detectable?

  • Distance from instrument: mostly 1/r3 dependence.
  • Susceptibility different from host.
  • Noise-level well below detectability? Consider:
    • Geology
    • Man-made materials
    • Power & radio frequency sources
    • Magnetic storm activity
  • Run tests or models with a similar, known situation if possible.

2. Search Pattern

  • Define requirements:
    • Mapping of regional behavior – do a large grid
    • Rough location – do 1 point per target size
    • Precise location – do a careful grid + secondary lines over anomalies
    • Target characterization – do >3 points per target dimension
  • Probably target geometry. For example:
    • 2-D with known orientation, or small “3-D” object
    • Try to survey lines perpendicular to long dimensions
  • Usually, the ideal survey is tempered by economics.

3. Consider Noise and Error Sources

  • Temporal variations and instrument drift:
    • Use continuously recording base station instrument, or
    • Re-occupy one station at least once every 10 to 20 minutes
    • Keep sensor clear of magnetic objects, clothing, pockets, etc.
      • Note proximity of error-signal sources (ex. fences, power lines, etc.)
      • Use acquisition procedures that maximize consistency of readings

    As an example, imagine your task is to locate the buried pipes under small flat field. Here some issues to consider:

    • Assume for example that the area of interest is about 100m x 30m.
    • Pipes are 2-D, and orientation may or may not be well known.
    • What lines, line spacing, and station spacing would be appropriate given that you have a limited amout of time?
    • What features of the site will cause anomalies that may interfere with the target anomalies? Buildings for example.
    • Good note-taking is always critical, especially if you are using older manual instruments. Don’t forget detailed comments on the site.
    • What base-station recording interval is appropriate? Does the base station instrument have the same sensitivity as the survey instrument?
    • Are there likely to be temporal noise sources that are not smoothly varying? This can be a problem in urban settings if traffic is near one area of the survey site.
    • Ideally, generate rough plots to assess regions for more detailed surveying; either more lines or tighter spacing?
    • Consider cross (or “tie”) lines, especially if there might be targets parallel to survey lines.
    • “Iterative survey design” is easier if the instrument has a graphing capability built in. Then you can start with a course grid, then survey at tighter spacings in anomalous regions.

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    Magnetometer Hardware and Firmware – v6.0 Upgrade Delivered

    GEM is pleased to report that its Research and Development group has recently completed an upgrade of the CPU, analog board, backplane board and LCD. The upgrade delivers a number of benefits to users:

    • Lower power consumption – 10 to 15% decrease
    • Reliable CPU – Fewer components, greater reliability
    • Robust operation – Even in the most demanding conditions
    • Lower noise – 4 times better noise characteristics. Note that this level may or may not be achievable in the field due to operator noise (i.e. at this level of sensitivity, any magnetic contamination will play a role in readings)

    The v6.0 upgrade is available for new purchasers. Existing purchasers will not be able to upgrade as entirely new components are required.

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    The Last Word – Comments from Our Customers

    As usual, we leave the last word to our customers – our key focus in ensuring that we continue to serve the market effectively and to our customers’ satisfaction.

    “We have recently purchased the GSMP-40 Potassium Gradiometer from GEM Advanced Magnetometers for the Colorado School of Mines. The GSMP-40 has proven valuable for both independent research applications and especially for educational purposes. The ability of the GSMP-40 to rapidly gather high quality data has helped Mines keep our students on the leading edge of both applied and theoretical aspects of magnetic and magnetic gradient methods for geophysical exploration. Likewise, the gradiometer has proven valuable for quickly identifying underground utility targets on the Mines campus, where construction plans require knowledge of these targets in advance.

    In addition to the quality of the GSMP-40 gradiometer, I have found the quality and service of GEM Advanced Magnetometers staff to be wonderful. They have taken all comments, questions, concerns and requests seriously and have acted in a timely maner on each. In particular, they have gone above and beyond traditional support center obligations by immediately modifying the magnetometer’s software design at our request to improve data output quality and ease of teaching for large numbers of students.”

    Richard Krahenbuhl
    Ph.D. Candidate
    Colorado School of Mines

    “We took our GSMP-40 to North Dakota for a field project this summer and it worked wonderfully. Our intent was to compare the data recovered with the GSMP-40 to that recovered with a fluxgate gradiometer earlier. The GSMP-40 was MUCH faster and collected the data in a fraction of the time.”

    Dr. Tommy Ike Hailey
    Northwestern State University

    “We have four of your Overhauser magnetometers, GSM-19 (Standard Overhauser) and GSM-90 (EUROMAG). We are very satisfied with them, and are now considering buying more.”

    Bjorn Ove
    Auroral Observatory
    University of Tromso

    “We have had the GSM-19T (Proton) instrument for the last 5 years. It is giving very good results.”

    Dr.Vinit C. Erram
    Indian Institute of Geomagnetism

    “Good website!”

    Jamal Mbarak
    Shatry Gems Ltd.

    Important Note: Our goal is to only communicate with people who would like to hear from us. If you would like to stop your subscription, please click here. If you have received this message through a colleague and would like to beadded, please click here.

    Copyright 2005. GEM Systems, Inc. Advanced Magnetometers. All rights reserved with the exception of organizations that have contributed links to this issue. Our thanks to the contributors who have made this edition possible, and who are identified in the text of related articles or through their company websites. Note that some quotes relating to industry-specific trends may have been obtained from public-domain sources, and are not intended to promote GEM Systems, Inc. Other examples may not necessarily reflect GEM products; rather these examples are intended to illustrate the use of magnetics and magnetometry for selected applications.

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