9 Allaura Blvd, Unit 1,
Aurora, ON,
L4G 3N2
+1(905) 727-8886
GT-1A Airborne Gravimeter
The GT-1A airborne gravimeter is a world-leader in its class.
For accuracy, resolution, productivity and dynamic range,
its technology is superior to traditional zero-length spring devices.

GT-1A Airborne Gravimeter

The GT-1A airborne gravimeter brings proven design and fully automatic operation to mobile scalar gravity measurement.  Intelligent Platform Control combined with continuously recorded wide dynamic range allows the collection of high quality data through periods of turbulence. Proprietary software provides on-side delta-g values for post-flight evaluation.

  • Easy installation
  • Rugged construction
  • Low power consumption
  • Rotary or fixed-wing installation
  • Automated warm-up & calibration
  • Automated operation (no operator on board)
  • Optimum data quality in a variety of flight conditions
  • Sensitivity 0.1 mGals
  • 300 Hz sampling and 18.75 Hz data recording
  • Dynamic range : +/- 500 Gals

The wide dynamic range provides high precision data in calm to turbulent flying conditions; data is acquired through short periods of saturation in extreme turbulence by the automatic application of a reduced-order Kalman filter, enabling platform misalignment to be computed and hence controlled;  the automatic calibration program computes accelerometer scale factors and errors in perpendicularity between the accelerometer sensitive axis and the platform surface.  The GT-1A installation in a fixed wing aircraft is shown in Fig 1 (courtesy of Airborne Petroleum Geophysics Ltd)

The GT-1A is hermetically sealed for protection when operating in environmental extremes.  Short lead-ins improve survey efficiency and reduce costs.  Filters depending on aircraft speed and flight conditions provide spatial resolution typically ranging from 1.2 kms to 3.5 kms.

Parameter Value Units
Measurement range 9.75 to 9.85 m/sec
Dynamic range +/- 500 Gal
Static repeatability +/- 0.3 mGal
Resolution 0.02 mGal
Drift per day (corrected) < 0.1 mGal
Roll Limit +/- 45 degree
Pitch limit +/- 45 degree
Operating temp +10 to +50 degree C
Power 150 at 27Vdc Watt
Weight (without rotation table) 134.5 kg
Dimensions (without rotation table) 400 x 400 x 600 h mm
Parameter Value Units
Standard deviation in gravity anomaly estimation +/- 0.60 mGal
Under the following conditions    
maximum vertical acceleration GT-1A +/- 500 Gal
constant barometric altitude +/- 5 m
dual frequency GPS receivers of at least 2 Hz
minimum number of visible satellites 6  
PDOP < 2.5  
GPS baseline < 100 km
Low-pass filter 100 Hz

Fig. 1 The GT-1A installation in a fixed wing aircraft (courtest of Airborne Petroleum Geophysics Ltd)
Fig. 2 Fixed-wing repeat line RMS Error = 0.5 mGals
Fig. 3 The GT-1A inertial platform design allows 45 degrees of roll or pitch during measurement. Built-in intelligent filters allow high quality data to be collected during periods when the aircraft motion briefly exceeds specifications of +/- 500 Gals.
Fig. 4 Fixed-wing grid survey over the Vredefort Dome southwest of Johannesburg (FAS 2004): NS lines spaced 1 km; left image is ground data courtesy the Geoscience Council of South Africa; right image is GT-1A data.
Fig. 5 To ensure that each GT-1A meets tough specifications, it must pass a variety of rigorous quality control tests.