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AIRBORNE EQUIPMENT
Data Acquisition System (DAS):
The data system is a SDAS1 data logger from KroumVS Instruments. The
system receives, displays and records the data from the three
magnetometers, all the analogue instruments and the spectrometer.
Data is recorded on compact flash or secure digital memory cards.
Survey navigation is provided by a LiNav-3D system from Ag-Nav Inc.
The system consists of an integrated computer/monitor/keypad and a
colour LED digital pilot display (array of 28 by 30 lines) that
shows horizontal cross-track and vertical elevation simultaneously
along with other pertinent navigation information. The primary GPS
receiver provides the system with real-time corrected horizontal and
vertical positional information for precise guidance along the
pre-programmed survey flight grid. For 3D drape flying an elevation
grid is input which has been calculated from a digital elevation
model (DEM) and the aircraft climb characteristics. Vertical input
to the system can be GPS altitude or radar altimeter. Mag Counter and Analogue to Digital Converter:
The heart of the airborne equipment is a KMAG4/KANA8 pair from KROUM
VS Instruments Limited. All analogue data (radar altimeter,
barometric altimeter, fluxgate magnetometer, and outside air
temperature) are digitized by the KANA8 24 bit A/D converter at the
desired data rate, 10 to 100 Hz, which is then passed onto the KMAG4
along with the GPS data. The KMAG4 four channel magnetometer counter
samples the magnetometers at the desired rate, assembles the mag,
analogue, and GPS data, time stamps it with the GPS UTC time and PPS
pulse and outputs to the DAS. GPS Receiver:
The primary GPS receiver is a NovAtel ProPak-LBplus 24 channel
L1/L2/L-band kinematic grade GPS receiver. The LBplus features Pulse
Aperture Correlator tracking technology that virtually eliminates
the effects of multipath and L-band services from either OmniSTAR or
CDGPS providing real time corrections for sub-meter accuracy. The radar altimeter is a King KR10A with a range of 40 to 2500 feet and a precision of +/-1 foot. Output is analogue. Barometric Altimeter:
The barometric pressure is measured with a Setra model 276 precision
pressure transducer. Operating range is -20 to +80°C with an
accuracy of 1.25 millibars. Output is analogue. Fluxgate Magnetometer:
A Bartington Mag-03MS three axis magnetic field sensor is used to
measure the aircraft attitude for post flight compensation of the
airborne magnetometer data. Output is three channel analogue. Airborne Magnetometers:
The magnetometers are Scintrex CS-2 and CS-3 and Geometrics 822A
cesium sensors operated in strap down mounts. The orientation of the
sensors is adjustable, to provide optimum coupling with the earth’s
field on reciprocal headings. The measurement range of the
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. Digital Video System:
An iCAM digital video system with input from a colour video camera
mounted in the belly of the aircraft is used to record the ground
track of the survey aircraft. The iCAM records the flight track as
MPEG4 AVI movie files on a removable hard drive. The digital movie
images have the project number, flight number and line number
overlain on the left side of the image with the GPS UTC time in
seconds, latitude and longitude position on the right side of the
image. The video is recorded at 3.755 frames per second with the GPS
information updating once per second. The files, which are recorded
as separate files for each survey line and are numbered by flight
and line number, can be played back using Windows Media Player with
the MPEG4 codec. Spectrometer: The spectrometer is a Pico Envirotec GRS-10 intelligent spectrometer coupled with a detector array of nine 4.2 litre NaI crystals. One of the detectors is upward looking only for cosmic/background corrections. The other eight detectors constitute the downward array with a total volume of 33.4 litres (2048 cu. in.). The spectrometer outputs the full 256 channel spectrum for both the upward and downward arrays for full spectrum processing using the Praga-3 software.
VLF Electromagnetic Receiver: The VLF-EM receiver is the industry standard TOTEM-2A manufactured under contract by RMS Instruments Ltd. The TOTEM-2A has three orthogonally mounted coils which measure the total field strength and the vertical quadrature component of the magnetic VLF field. Airborne VLF EM data are mainly used for geological mapping, interpretation of large scale geological features, such as faults and shears, and locating graphite and base metal conductors.
Base Station Equipment: An SDAS1-PPC pocket pc data logger is operated as a base station collecting data from a KMAG4 counter receiving input from a Scintrex CS-2 cesium magnetometer sensor and a Novatel DL-4plus high-accuracy 24 channel L1/L2 dual frequency GPS receiver. The GPS and magnetic data are recorded continuously throughout the survey flights in digital form. Both the ground and airborne data are automatically time stamped with GPS time to within 0.05 seconds ensuring a very high degree of correlation based on the broadcast GPS PPS pulse. Click on the logos bellow to visit their websites
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