(click on the pictures to enlarge them)
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.
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 FreeFlight TRA-3000 coupled with a TRI-40 digital indicator. The altimeter
has a range of 40 to 2500 feet
and an accuracy of 5%. Output is analogue.
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.
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.
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 Flight Track System:
A Stack DVR3-130 digital video & data recorder 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 DVR3 is a compact solid-state video recorder
with data input from the primary GPS receiver. The date, GPS time in
seconds, latitude and longitude position are overlain on the video
image on the top left side of the video frame. The video files are recorded
as mpeg-2 compressed files with a separate file per survey flight line.
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
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.
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