Geometrics G-858 Cesium Vapor Magnetometer - A Professional Magnetic Mapping System for High Resolution & Rapid Surveys

Description Configuration Options Feature Summary Specifications


G-858 Description

G858 Console - Click for larger picThe G-858 MagMapper uses a graphical interface to make survey design and data acquisition quick and efficient. Various modes of operation allow the user to custom design a survey grid for their particular needs. The operator also has the ability to view his/her position on the grid and the current data profile during the survey. Sensitivity, resolution, and recording rate of the cesium magnetometer are user selectable.

G-858 data acquisition offers either continuous or discrete station recording. The high sampling rate of the instrument in continuous mode allows the operator to survey an area at a fast walking pace. A wider search radius can be achieved by using a gradiometer configuration. As a result, over-all costs are inherently lower while data quality remains high.

The G-858 is designed to interface easily with standard computers and peripherals.


G-858 Configuration

The G-858 MagMapper system comprises a belt-mounted display/logging console connected to a cesium sensor mounted on a hand-held counterbalanced staff. The console contains electronics to acquire magnetic field data with position and display it on an LCD screen for review and edit. The console stores high volumes of data in memory. Following the survey the data is transmitted at high speed to a processing computer for detailed analysis.

G858 Components - Click for labelled pic A basic software package - MagMap, is supplied as an integral part of the G-858 system. It provides:
  • Transfer of the raw data to the client PC;
  • Standard corrections for position errors, transients, and time varying errors (diurnal);
  • Repositioning, linear interpolation and format corrected data into X,Y,Z ASCII columnar values for use with various contouring programs.
  • Parsing of GPS data to magnetic data set


G858 Gradiometer.jpg (7414 bytes)

G-858 being used in gradiometer mode

G-858 Options

  • Our recently developed maximum likelihood dipole pattern matching software MagAIDTM allows the user to generate estimations of object x-y position, size and depth.
  • Using the supplied RS-232 port, the G-858 is able to interface to customer supplied GPS (Global Positioning System) or other data source.
  • A gradiometer configuration (either horizontal or vertical) is available with the addition of a second cesium sensor and staff attachments.



G-858 Features

  • High Sensitivity - Easily detect a single drum buried 6 meters
  • Very Fast - Cover two acres per hour at 2 meter line spacing.
  • Immediate User Feedback - Display Earth's field survey grid, position and 5 stacked survey profiles.
  • Easy to Use - Produce hard copy maps at base site within minutes using standard IBM-compatible computers and peripherals.
  • Options - Simultaneous vertical or horizontal gradiometer, Differential GPS positioning, Target analysis software.

G-858 Specifications

Operating Principle: Self-oscillating split-beam Cesium Vapor (non-radioactive Cs133) with automatic hemisphere switching. Heading Error: +/- 1 nT
Operating Range:
17,000nT to 100,000 nT
Gradient Tolerance:
 > 500nT / inch; >20,000nT / meter
Operating Zones: For highest signal-to-noise ratio, the sensor long axis should be oriented at 45o, +/- 30o to the earth's field angle, but operation will continue through 45o, +/- 35o. Data Storage: Nonvolatile RAM with capacity for 8 hrs. of Magnetometer time, event marks, field notes, location, or 3 hrs. of Gradiometer and GPS at maximum sample rates.
Sensitivity: 90% of all readings will fall within the following Peak-to-Peak envelopes:
  1. 0.05nT at 0.1 sec cycle rate
  2. 0.03nT at 0.2 sec cycle rate
  3. 0.02nT at 0.5 sec cycle rate
  4. 0.01nT at 1.0 sec cycle rate
Visual Display: A 320x200 graphic LCD, daylight visible with selectable outputs for:
  1. Data display
  2. System setup functions
  3. Survey setup functions
  4. Survey monitoring
  5. System diagnostics
Data Output: Three wire RS-232 standard serial port, optional continuous real time transmittal of data via RS-232 to PC. Total memory output transfer time less than 5 minutes at 115,200 baud Battery Life:
  1. 12 VDC rechargeable gel cell, 6 hrs. Magnetometer or 3 hrs. Gradiometer usage.
  2. Internal backup battery for clock and nonvolatile RAM
Operating Temperature:
 -25o C to +50o C (13o F to +122o F
Water Tight:
 To 3 ft. (0.9 m) depth
Shock: Drop 3 ft. on a hard surface without damage. Console Magnetic Effect: Less than 1nT at 4 ft. from sensor.

For more info or pricing contact Red Dog Scientific Services, authorized representative for South / Southern Africa