Over the last several decades, electromagnetic prospecting using Helicopter platforms has proven to be a popular and beneficial survey approach. Consistent with this trend, NUVIA Dynamics has focused significant Research and Development efforts on developing a user-friendly and versatile electromagnetic system called NuTEM™. The system is intended for resource exploration, near surface geotechnical work and environmental studies.
With its dipole moment of up to 250,000 Am, the NuTEM™ system is well suited for surveys with Depths of Investigation to 350 m (geology specific). NuTEM™ has a small foot-print and is robust – factors that have contributed to the adoption of NUVIA Dynamics’ system as one of the leading options on the market today.
NuTEM™ is a versatile state-of-the-art time-domain helicopter-borne Electromagnetic system. Weighing less than 350 kg on-hook, it features a powerful transmitter, a 3-component receiver, an integrated data acquisition system with survey navigation, and digital signal processing software package.
The system collects the 3-axis (X, Y and Z) response from the ground recorded in continuous mode. The collected data can be extracted into specified ON-TIME and OFF-TIME decay gates according to the aims of the project.
Components include a 3-axis receiver, current monitor, orientation re-calculation technique developed by NUVIA Dynamics, as well as transmitter platform positioning sensors. This gives a wide range of tools available for acquisition and treatment of the resulting data.
Unlike other commercial systems, the NuTEM™ is designed to be integrated on NUVIA Dynamics’ IMPAC-M platform – delivering a complete solution with ancillary magnetic and spectrometer results which are synchronized with the time domain system.
Image of Loop Transmitter System with Helicopter. Features on-board power generation and ease-of-flight for low noise and high signal quality
The system is a special Slingram configuration which provides results that are largely free of the transmitter dipole moment – remaining effects are then removed in software.
Features
NUVIA Dynamics’ NuTEM™ system features:
- Powerful, compact transmitter with smooth-fly characteristics for low noise.
- Three axis receiver with X, Y and Z components fully resolved and noise-free.
- Digital data acquisition via the NUVIA Dynamics’ IMPAC system with full system control.
- Lightweight for easy transport and operation with streamlined vertical lift.
- Full wavelength recorded data for custom extraction and processing.
- Windows configurable for different geologic targets.
Benefits – General
This powerful form of Electromagnetic prospecting delivers a number of unique benefits:
- Enhanced geologic resolution for finely detailed conductors and structure.
- Intermediate depth penetration suitable for many prospective exploration sites.
- Light weight and low-noise profile in flight and in measurement of X, Y and Z responses.
- Comprehensive software capabilities for data extraction and initial windowing.
Benefits – Rugged Terrain
- Compact footprint for better defined anomaly positioning.
- Stable, rigid platform for noise reduction in X, Y and Z data.
- Optimal loop size for exploring in rugged terrain.
NuTEM™ System Description
This section describes the transmitter, receiver and detailed system specifications.
Transmitter
The transmitter delivers a half-sine wave pulse of a quarter duty cycle (25% pulse length) with a peak magnetic dipole moment to 380,000 NIA. The system can support two base frequencies, for example, 30 Hz and 90 Hz for a 60 Hz environment or 25 Hz and 75 Hz for 50 Hz environment. The transmitter current is fully monitored at all times.
Receiver
Nu-TEM features a powerful and compact three-axis receiver that records in X, Y and Z channels for effective mapping of anomalies (Z channel) as well as mapping of structure (X channel). Data are clean and well-behaved for transmitter off times.
System Characteristics
The NuTEM™ system has been fully tested at the Reed Mahaffey test site in northern Ontario – a well-known area flown by all major airborne contractors. NUVIA Dynamics’ flights in 2019 established new milestones for very high resolution (VHR) and mapping of individual conductors. It has also been flown for major mining companies.
Comparison of NuTEM™ Z channel responses for a range of windows.
The Latest in Proven Electromagnetic Surveys and Technology
NuTEM™ Specifications
Technical Specifications Description
Type NuTEM
Standard Survey Speed 55 to 60 Knots
Sensor Configuration Slingram
Surface Area 55 sq m
Weight 300 kg
Structure Rigid Loop with Aluminum Frame
Estimated Resistance 15 mOhm
Transmitter Power Generation in Centre of Loop
Suspension Single Point
Integrated Systems Magnetics (Radiometrics – Optional)
Aircraft Type Bell 206 Ranger, MD 500, AS350 or Similar
Sampling Rate 90 kHz, Each Sample ~10 μs
Transmitter
Description 4 Turn Nonagon
Diameter 8.6 m
Current 1000 A Peak
Dipole Moment 220,000 NIA
Waveform Type Half Sine; Vertical Dipole
Pulse Length 25 % of Full Cycle
Base Frequency 25 / 75 Hz in 50 Hz Environment; 30 / 90 Hz in 60 Hz Environment
Waveform On Time from 451.1 to 1655.4 Microseconds
Power Source Onboard generator
DC Power Generation 400 Hz 125VAC Helicopter Generation
Mean Ground Clearance 30 m
Receiver
Axes X, Y and Z component measurements
Position Offset to TX
Diameter 28.5 cm
Number of Turns 240 Turns on Each Component
Orientation Z Axis
Preamplifier 3 Channel
Configuration Offset to TX (Front and Above TX)
Sampling 90 Hz
Time Gates Configurable with text file – 52 gates
Measurements dB/dT & integrated B field
Mean Ground Clearance 60 m
Acquisition System
Type NUVIA Dynamics’ IMPAC
CPU I7 Generation 2 Quad Core
Operation Temperature Degrees Celsius (-35 to 45)
Standard Sampling Rate 20 Hz
Magnetometer Counter
Magnetometer NUVIA Dynamics’ MMS8
ADC inputs 0.707 V Peak to Peak – 2 Second Polarization
Magnetometer Inputs 8 Inputs
Recording Rate Up to 100 Hz
Analog to Digital Conversion 24 Bit
Noise Envelope 0.002 nT peak-to-peak and 0.1 to 1 Hz bandwidth
Base Station Magnetometer
Type CS-3
Manufacturer Scintrex
Range 15,000 nT to 105,000 nT
Sensitivity Recording Rate 0.0006 nT Root(Hz) RMS @ 1 Hz
GPS
Type Hemisphere R330
Differential Correction Real Time
Number of Satellites 25+
Recording Rate 10 Hz
Temperature
Type NUVIA Dynamics P-DES
Full Scale -20 to 85 Degrees C
Resolution 0.036 Degrees C
Recording Rate 1 Hz
Barometer
Type NUVIA Dynamics P-DES
Full Scale 0.1600 hPa
Temperature Compensated Range 10.90%
Accuracy +/- 0.25%
Resolution 0.39 hPa
Recording Rate 1 Hz
Radar Altimeter
Type FreeFlight Systems’ RA-4000 mounted on aircraft
Operating Range 0 to 2500 feet
Accuracy (0 to 100 ft) 3%
Accuracy (100 to 500 ft) +/- 3%
Accuracy (500 to 2500 ft) +/- 5%
Recording Rate 1 Hz
Laser Altimeter
Type LDM302A
Range 0.5 m to 200 m for low reflectance targets; otherwise up to 3 km
Resolution 1 mm
Recording Rate 1 Hz
Humidity
Full Scale 0 to 100%
Temperature Compensated Range 10.90%
Accuracy +/- 1.7% RH
Resolution 0.04%
Operating Temperature -40 to 125 Degrees C
Unit of Measure %
Software
Data Acquisition NuTEM™ Console
Survey Control & Data Storage NUVIA Dynamics’ IMPAC Data Acquisition Unit
Windowing & TX Loop Removal EMDATAView (proprietary)
Processing and Display Geosoft
Examples and Contacts
See this video of our P-THEM system test flight- 2013
The results of test and demonstration flights are being presented yearly at different international conferences and conventions, including AGU, SAGEEP, KEGS and others.
For detailed information on NuTEM™ products or survey solutions, please email info@nuvia-dynamics.com.