Bringing a new level of flexibility to non-invasive groundwater investigations, the GMR Flex is built on a versatile architecture of modular, adaptable, and highly portable components, engineered with the familiar rich features, high precision, and field ruggedness of the deeper-imaging GMR.


Highly Portable Surface NMR

  • Designed for economy and efficiency
  • Easily expandable configurations
  • Optimized for shallow investigations
  • Ultra-short dead-time
  • Accepted as airline checked luggage

Compact & Flexible Form Factor

Packaging the most advanced features into a lightweight platform, GMR Flex enables fast and efficient surveying of shallower groundwater systems. Modular components can be combined to optimize depth of investigation while minimizing equipment weight and size. In its most compact configuration, the GMR Flex Transmitter can be operated from batteries with no additional modules. Modules for Tuning and DC capacitance can be added to increase output power and depth of investigation. In addition to standard GMR features, the GMR Flex also includes ultra-fast switching for dead-times of less than 1 ms.


2000V GMR Flex

Operable as a single unit or with expansion modules


  • Maximum coil output: 2000V, 400A
  • Bus voltage: 250V
  • Ultra-short dead-time: <1ms
  • One full-duplex Tx/Rx channel & one Rx-only channel
  • Wideband receiver noise <300pV/rt(Hz)
  • Pulse sequences with phase cycling: FID (T2*), 4-Phase (T1), Spin echo & CPMG (T2), Adiabatic sweeps†
  • Compatible with separated transmit and receive loops


  • Analog voltage meters on panel
  • Auto-shutdown in case of improper connection
  • Environmentally-rated connectors with no-touch contacts

DC Capacitor Expansion Module


  • Capacitance: 66mF


  • Auto-shut down for safety in case of improper connection
  • Fast voltage-bleed circuit

Two Channel Rx Expansion Module

Adds two high-voltage receive channels with short dead-time

Tuning Expansion Module


  • Capacitance: 15.5μF
  • 2400Vrating


  • Auto-shutdown in case of improper connection
  • Transmitter operates only when tuning lid is securely closed and shuts down if opened

High-Voltage Surface Cables

Durable insulation with environmentally rated connectors