A Pico Airborne Geophysical Information System (AGIS) digital data logger collects and records all applicable geophysical and navigational data, including X-Y-Z GPS position data, time, date, 256 channels of radiometrics, total field magnetics, compensated total field magnetics, two-channel VLF-EM, laser altimeter, barometric pressure, temperature, and humidity. Real-time QA/QC software provides data which are monitored in flight by a geophysicist or trained geophysical operator.
Airborne Magnetometer Sensor
A Scintrex CS-3 non-radioactive cesium sensor is used to sample the earth's magnetic field at 10 Hz. The orientation of the sensor is adjustable, to provide optimum coupling with the earth's magnetic field on reciprocal headings. The measurement range of this state-of-the-art magnetometer is 15,000 nT to 100,000 nT with a peak to peak noise envelope of 0.002 nT in the 0.01 to 1 Hz bandwidth. The final data are tie line levelled and/or micro-levelled and includes corrections for diurnal fluctuations, IGRF and system parallax. Mounting the magnetic sensor in a fixed boom configuration helps to ensure that the geophysical data are collected at a low and uniform height above the Earth's surface, and optimizes the flight characteristics for simultaneous radiometric data collection. For specialized survey requirements, we offer a multi-sensor configuration to provide 3-axis magnetic gradients useful for identifying shallow targets in flat terrain.
During survey flights, movement of the survey aircraft interferes slightly with the geomagnetic field which is being measured. This small but significant variance is corrected in real time with a Bartington Mag-03 three-axis fluxgate magnetic field sensor, which provides reliable vector measurements of static and non-static magnetic fields in all three orthoganol axes. High-altitude compensation flights with prescribed pitch, roll, and yaw maneuvers "train" the compensation system for magnetic latitude, flight line orientations, and individual aircraft. A Figure of Merit (FOM) is calculated for each of the 36 specified flight maneuvers for the four cardinal survey flight directions.
The MMS-4 magnetometer processor is a high resolution (0.2 pT), fast sampling (20 Hz) magnetometer processor unit that continuously measures the magnetic signals from up to four magnetometer sensors. It is carried on board the aircraft and provides real-time magnetic compensation of the airframe motion.
Precision's fully certified (Supplementary Type Certificate) nose-mounted stinger carries the magnetometer sensor and VLF-EM receiver. The forward part of the stinger system contains the CS-3 magnetometer sensor, the central part contains the magnetic compensator and the VLF-EM receiver, and the aft part contains the laser altimeter. This innovation eliminates the traditional towed bird system and offers significant advantages in data quality, pilot work load reductions, survey flight efficiencies, and safety in all types of terrain.
The aft end of the magnetometer boom contains an Acuity AccuRange AR3000 laser altimeter to provide the pilot with terrain guidance. The infrared laser is eye-safe (Class 1) and is accurate to within 10 cm. Data from the laser altimeter are recorded to assist in data processing and, when combined with 3D GPS position data, have the added benefit of producing digital topographic maps (DTM) of the survey area.
Base Station Magnetometer System
Precision uses computer-controlled Geometrics G-856AX, Scintrex EnviPro, and GEM GSM-19T proton magnetometers with well proven proton precession technology, allowing accurate measurements to be made with virtually no dependence upon variables such as sensor orientation, temperature, or location. These units provide repeatable absolute total field magnetic readings, traceable to the National Bureau of Standards. Data are recorded digitally from a fixed ground position near the survey area for monitoring, recording, and correction of the earth's diurnal field shift.