WTRMP Hummingbird HEM survey 2001-2002 Sengpiel Conductivity-depth sections have been output as ASCII data (*.ACD), and as Geosoft databases (*.gdb) ASCII data is contained in files: dolcoath_sengpiel.acd balfour_sengpiel.acd mrv_sengpiel.acd meredith_sengpiel.acd Geosoft databases have the same root filename, with the extension *.gdb. An example of the file format is given at the end of this readme file. There are 11 columns in the ASCII data files. A complete description of the file is given below. COL 1: Line (Line number) COL 2: East (Easting TMAMG55, AGD66) COL 3: North (Northing TMAMG55, AGD66) COL 4: Fid (Fiducial) COL 5: Alt (Radar altimeter BIRD altitude - metres) COL 6: Freq (Frequency - Hz) COL 7: rhoa_ohmm (Apparent resistivity - ohm.m, inphase-quad algorithm) COL 8: cona_mS_per_m (Apparent conductivity - milliSiemens/m, inphase-quad algorithm) COL 9: zp* (Centroid depth - metres .. NB: depths are negative BELOW surface) COL 10: DTM (Digital terrain model derived from radalt/GPS elevation data) COL 11: DTM+zp* (Elevations of centroid depths, given by adding cols. 9 and 10) ----------- Note: There may be up to 5 records at any given (Easting, Northing) - one per frequency. At most stations there will be less than 5 records due to noise or errors in the data at the lower frequencies. A noise cutoff of 2.5 ppm has been applied in order to suppress artifacts in the Sengpiel sections in areas of low signal. Apparent conductivity and centroid depth are NOT computed in the following situations: HCP data: in-phase and/or quadrature response negative in-phase and/or quadrature data < 2.5 ppm VCX data: in-phase and/or quadrature response positive in-phase and/or quadrature data > -2.5 ppm The effect of magnetic polarisation or displacement currents on the measured HEM responses is NOT accounted for in the Sengpiel transformation. ----------- Example file format (ASCII *.ACD): NB Turn word wrap off to view the format correctly! Line East North Fid Alt Freq rhoa_ohmm cona_mS_per_m zp* DTM DTM+zp* 70011 335024.90 5373571.40 7322.00 40.50 880.0 0.3409046E+03 0.2933372E+01 -134.86 12.97 -121.89 70011 335024.90 5373571.40 7322.00 40.50 6600.0 0.4507533E+03 0.2218508E+01 -46.18 12.97 -33.21 70011 335024.90 5373571.40 7322.00 40.50 7000.0 0.1697890E+03 0.5889662E+01 -41.76 12.97 -28.79 70011 335024.90 5373571.40 7322.00 40.50 34000.0 0.1964617E+03 0.5090050E+01 -15.66 12.97 -2.69 70011 335027.20 5373569.00 7324.00 40.90 880.0 0.3423310E+03 0.2921149E+01 -134.64 13.37 -121.27 70011 335027.20 5373569.00 7324.00 40.90 6600.0 0.4476752E+03 0.2233762E+01 -45.60 13.37 -32.23 70011 335027.20 5373569.00 7324.00 40.90 7000.0 0.1703100E+03 0.5871647E+01 -41.37 13.37 -28.00 70011 335027.20 5373569.00 7324.00 40.90 34000.0 0.1965775E+03 0.5087051E+01 -15.26 13.37 -1.89 70011 335029.50 5373565.40 7326.00 40.40 880.0 0.3524481E+03 0.2837297E+01 -137.00 13.07 -123.93 etc etc