The Geode EM3D is a revolutionary instrument capable of high-resolution, high-quality resistivity mapping to depths of 1,000+ meters.  The Geode EM3D has the flexibility to do traditional audio magnetotellurics (AMT), hybrid-source AMT (HSAMT), and controlled-source AMT (CSAMT). For CSMAT configurations, a high power transmitter is provided. Traditional electromagnetic (EM) methods require multiple station setups and are time-consuming, thus impractical for obtaining the high resolution required in today’s competitive mining environment. The Geode EM3D allows a single setup of all stations and one transmitter run for acquisition of all 50 sounding at the same time.

The Geode EM3D allows for closely spaced soundings based on a common network of stations, and for greater flexibility, the instrument is designed to interface to a range of commercially available controlled-source geophysical transmitters. The Geode EM3D can be used as a single-receiver, six-channel instrument with (HSAMT or CSAMT) or without a transmitter (AMT).  The individual receiver modules can also be linked together in a reliable Ethernet network for from 12 up to 120 channels and more of EM sensors. With the Geode EM3D complete your surveys faster and in higher resolution, taking the guesswork out of mineral exploration!


Features and benefits

  • Excellent Data Quality: Collect excellent data even in the high-frequency dead zone for high-quality measurements from 0.1 Hz to 20,000 Hz. Ultra-low noise analog front end. Get great data from shallow to deep on a single sounding.
  • Easy Expandability: Using a reliable Ethernet network solves the problems of GPS dropouts or lost satellite lock, line-of-sight communication failures, radio of WiFi communication failures, and blocked antennas.
  • Simultaneous Soundings: Perform three simultaneous soundings with a single receiver and six soundings at the same time with two receivers – more data in less time than traditional instruments.
  • Field Flexibility: Survey using audio magnetotellurics (AMT), hybrid-source audio magnetotellurics (HSAMT), and controlled source audio magnetotellurics (CSAMT) with the addition of the controlled-source transmitter. Either scalar of full tensor calculations for both AMT and CSAMT operations.
  • Real Time Data: View a real-time display of apparent resistivities, impedances, phase, Bostick true resistivity and depth values, MT rotation values, tipper calculations, and more even during acquisition! More data for quality control to know the quality of the data immediately in the field.
  • Built In Troubleshooting: Automated contact resistance measurements on all electric dipoles. Automatic AC and DC noise values on all electric and magnetic channels – tells you what is your noise environment and provides troubling shooting tool.
  • GPS: Calculate all GPS positions for an entire survey line with a single GPS measurement for any one dipole – fast accurate GPS positions
  • Control Your Data: Export of multiple file types for use in third-party processing, inversion, and interpretation software supported.  Examples are AVG files for Zonge SCS2D software, EDI files for Schluberger’s WinGLink – CGG’s GeoTools – most academic software, DAT files of Bostick values for Surfer or other contouring programs.

Technical Details

Geode EM3D Specification List

Geode EM3D

Operating Principle: Controlled-source audio-frequency magnetotellurics (CSAMT) is a high-resolution electromagnetic sounding technique that uses a fixed, grounded dipole or horizontal loop transmitter. Audio magnetotellurics (AMT) uses naturally-occurring electrical sources in the atmosphere. Hybrid-source audio-magnetotellurics (HSAMT) uses both natural and man-made signals.

  • Frequency Range: 0.1 Hz to 20 kHz.
  • Electric Sensors: Choice of either porous pot non-polarizing or stainless steel stakes.
  • Magnetic Sensors: Model G20K (0.1 Hz to 20 kHz) magnetic field sensor with 20 meter cables.
  • Data Format: ASCII columnar.
  • Data Collection Station GEM3D Receiver Channels: up to 6 channels per station
  • (Ex1, Ex2, Ey1, Hx, Hy, Hz)
  • (Ex1, Ex2, Ex3, Ey1, Hy, Hx)
  • (Ex1, Ex2, Ex3, Ex4, Ey1, Ey2)
  • Sample Interval (SI): Automatically selected in CSAMT mode.
  • Maximum Record length: 64 K.
  • Analog to Digital Conversion: 24 bits.
  • Dynamic Range: 144 dB (system), 110 dB (instantaneous, measured) at 2 ms, 24 dB.
  • Noise floor: 10 nV/ Hzrms @ 24 dB.
  • Storage Memory: PC system dependent.
  • Gain Settings: 24 dB, 12 dB, 0 dB, -12 dB.
  • Maximum Distance from receiver: 250 m between receivers, 100 m first receiver to PC.
  • Analog Receiver Input Impedance: > 2.0 MOhm (W/Analog Front end).
  • Power source and consumption: Geode EM3D Receiver 12V external battery, 9 Watts for 6 channels.
  • Operating Temperature: -20°C to +70°C (-4°F to +158°F).
  • Physical Dimensions: GEM3D receiver L: 24 cm; W: 16 cm; H: 19 cm.
  • Weight: 5.2 kg (6.5x6.5x3.25 in; 183 oz).
  • In-field QC: Time series, apparent resistivity and phase versus frequency sounding curves with standard deviation or error bar, component operation check, automated contact resistance measurement.
  • Maximum signal input voltage: +/- 12 V peak, +/- 9 V peak before distortion increase.
  • Clock Accuracy: 0.4 ppm over temp range, +/- 2ppm/year without factory calibration.
  • Phase Matching: 1 degree <1 kHz, 3 degrees< 10 kHz.
  • Amplitude-Phase Channel Matching: 1%.
  • Amplitude Accuracy: 1%.
  • Distributed System Parameters
  • Maximum Channels: 240 channels.
  • Communication Protocol: 10 Mbit Ethernet.
  • GPS Synchronization: Synchronized transmitter to acquisition stations
Geode EM3D Shipping Weights & DIMS

Shipping Weights & DIMS

Contents Dimensions (L x W x H) Weight
Case 1 - Geode EM3D Instrument Only 10in x 7in x 8in
24cm x 16cm x 19cm
Case 2 - Single Geode EM3D w/ Laptop (no transmitter) 4-5 boxes 143lbs


  • Mapping of geology to 1,000 meters and more for mining and minerals exploration
  • Mapping of hydro-geologic features for groundwater exploration
  • Geothermal reservoir mapping to 2,000 meters depth
  • Shallow oil and gas exploration to 2,000 meters depth
  • Deep geotechnical and engineering application such as mapping of deep structure for future dam sites, characterizing potential nuclear waste deposit integrity, view geology
  • structure for deep mountain tunneling, etc
  • Excellent tool for academic research and teaching

Geode EM3D Espanol Infographic

Download the Geode EM3D Espanol Infographic