COMM GENERAL
COMM
COMM Project                       Lefroy
COMM Survey area                   Lefroy-West
COMM Located data type             0.1 Second Final Data
COMM
COMM Surveyed by                   GPX AIRBORNE PTY LTD.
COMM Job number                    Lefroy
COMM Processed by                  GPX AIRBORNE PTY LTD.
COMM Creation date                 June 2007
COMM
COMM SURVEY SPECIFICATIONS
COMM
COMM Survey flown                  March-April 2007
COMM Traverse line spacing         100 metres
COMM Traverse line direction       090-270 degrees
COMM Tie line spacing              1000 metres
COMM Tie line direction            000-180 degrees
COMM
COMM Survey height                 90 metres
COMM
COMM LOCATED DATA FORMAT
COMM
COMM Variable                      Units          Undefined      From  To    Format
COMM
COMM Line number                                  9999999        1     8     I8
COMM Easting (GDA94, MGA55)        metres         9999999.99     9     19    F11.2     
COMM Northing (GDA94, MGA55)       metres         9999999.99     20    30    F11.2     
COMM Fiducial                                     99999.99       31    39    F9.2
COMM Flight number                                999            40    43    I4
COMM Direction (1=E, 2=N, 3=W, 4=S)               9              44    45    I2        
COMM Date (YYYYMMDD)                              99999999       46    54    I9
COMM Time (GPS)                    seconds        99999.99       55    63    F9.2
COMM Longitude (WGS84)             degrees        999.999999     64    74    F11.6
COMM Latitude (WGS84)              degrees        999.999999     75    85    F11.6
COMM Radar altimeter               metres         9999.9         86    92    F7.1
COMM GPS altitude                  metres         9999.9         93    99    F7.1
COMM Raw magnetics                 nT             99999.999      100   109   F10.3
COMM Post compensated magnetics    nT             99999.999      110   119   F10.3
COMM Diurnal                       nT             99999.999      120   129   F10.3
COMM Final magnetics               nT             99999.999      130   139   F10.3
COMM Pressure                      millibars      9999.9         140   146   F7.1
COMM Temperature                   degrees C      99.9           147   151   F5.1
COMM Raw total count               cps            999999         152   158   F7.0
COMM Raw potassium                 cps            9999           159   163   F5.0
COMM Raw uranium                   cps            9999           164   168   F5.0
COMM Raw thorium                   cps            9999           169   173   F5.0
COMM Raw cosmic                    cps            9999           174   178   F5.0
COMM Final total count             cps            99999.99       179   187   F9.2
COMM Final potassium               cps            99999.99       188   196   F9.2
COMM Final uranium                 cps            99999.99       197   205   F9.2
COMM Final thorium                 cps            99999.99       206   214   F9.2
COMM Final DTM                     metres         99999.9        215   222   F8.1
COMM
COMM DATA PROCESSING
COMM
COMM COORDINATE DATA
COMM All lines are scissored to the following rules:
COMM   1) A 'smooth' edge outside the area boundary.
COMM   2) Maximum line overlap of 0 fiducials within
COMM      the area boundary.
COMM
COMM The local projection is a UTM projection based on the
COMM WGS84 spheroid with a central meridian of 147 East degrees.
COMM System parallax of 0.6 fiducial has been removed.
COMM
COMM MAGNETIC DATA
COMM The magnetic data has been corrected for regional gradient by subtraction
COMM of IGRF model 2005 computed continuously over the whole area based on
COMM the GPS height.
COMM Diurnal magnetic variations have been removed.
COMM System parallax of 1.6 fiducial has been removed.
COMM Tie-line levelling has been applied.
COMM Microlevelling has been applied.
COMM A base value of 61900 nT has been added to the data.
COMM
COMM RADIOMETRIC DATA
COMM
COMM Raw channel data provided has been energy calibrated
COMM NASVD has been applied to channel data prior to windowing
COMM System parallax of 0.0 fiducial has been removed.
COMM Height attenuated to 80m AGL
COMM Airborne radon has been removed
COMM
COMM AIRCRAFT BACKGROUND                                UNITS
COMM Total Count                           81.67          cps
COMM Potassium                             23.35          cps
COMM Uranium                                0.59          cps
COMM Thorium                                0.67          cps
COMM COSMIC STRIPPING RATIOS
COMM Total Count                        0.811201
COMM Potassium                          0.044663
COMM Uranium                            0.038646
COMM Thorium                            0.043791
COMM COMPTON STRIPPING RATIOS
COMM alpha                                 0.250
COMM beta                                  0.400
COMM gamma                                 0.810
COMM a                                     0.060
COMM HEIGHT ATTENUATION COEFFICIENT
COMM Total Count                        0.006928    per metre
COMM Potassium                          0.009043    per metre
COMM Uranium                            0.007186    per metre
COMM Thorium                            0.006892    per metre
COMM WINDOW ENERGY LEVELS             Low Energy High Energy
COMM Total Count                           410.0      2810.0          keV
COMM Potassium                            1370.0      1570.0          keV
COMM Uranium                              1660.0      1860.0          keV
COMM Thorium                              2410.0      2810.0          keV
COMM
COMM DIGITAL TERRAIN MODEL DATA
COMM
COMM DIGITAL TERRAIN MODEL CALCULATION
COMM The radar altimeter data was subtracted from the GPS heights to provide
COMM a digital elevation model which is height above the WGS84 spheroid. Using
COMM interpolation on the 120 second DMA Geoid model, a correction was computed 
COMM and subtracted from the WGS84 data to convert to height above the geoid.
COMM
COMM DATA RELIABILITY
COMM This Digital Terrain Model (DTM) has been computed from data generated
COMM during the course of an airborne geophysical survey flown at a nominal
COMM spacing of 100m and data has been interpolated between such lines.
COMM Every effort has been made to make this model a useful general reference.
COMM No guarantee can be made that this model is a true representation of height
COMM above sea level as it can contain radar altimeter responses from buildings
COMM and in some instances dense timber. Users of the product should be aware
COMM of the topographic limitations mapped herewithin. Do not use this DTM for
COMM navigation purposes.
