To check on the right coordinates of OS active stations, see the link below http://gps.ordnancesurvey.co.uk/active.asp Base station data not 1 second resolution? Resample (interpolate using posgps). While this doesn't improve the data, it apparently makes it more evenly applied (no internal interpolation?). Unverified. == Short notes on processing == 1. Understand what you're doing! 1. Create new project, aim at /applanix. Name should be '''"YYYYJJJ.ppc"'''. Both filename kernels should be '''"YYYYJJJ"'''. 1. Hit "Extract" 1. Kernel should be '''"YYYYJJJ"'''. 1. Read through output for errors - key things to look for are data gaps (if large, you may have to split the processing) 1. Hit "POSGPS" 1. Convert input files to GPB (File -> Convert -> Raw GPS to GPB) 1. Plane applanix 1. Set receiver type to autodetect 1. Point at the applanix/Extract directory (check this!) and 'Auto add all' (this should add a NovAtel OEM3 file) 1. Select the Novatel file, click options and ''Make all epochs Kinematic'' (this is because the Novatel is the sensor on the plane, which is definitely kinematic!) 1. Run the conversion (check output for errors) 1. Base stations (repeat for all base stations) 1. Set receiver type to autodetect 1. Point at the base station directory, probably Rinex, and 'Auto add all' (this should add a file, probably Rinex for the UK) 1. Run the conversion (check output for errors, some health warnings are ok) 1. ''File -> Add Remote File'', select the gpb file in the applanix/Extract directory, defaults fine 1. (for all base stations - note: multiple base stations may need other stuff done) 1. ''File -> Add Master File(s)'', select the gpb file in the basestation directory 1. (if you have gaps, it may offer to resample for you - not sure if we need to do this or not) 1. The basestation data will come with extra info specifying the precise location and antenna type. 1. Fill in the antenna type (use advanced method) if you have the info, otherwise set the height appropriately 1. The base station location will come in a particular datum/coordinate system - you '''must''' correctly convert this to a form that POSGPS knows about. 1. For UK base stations, see the instructions below for this conversion. --------------- == UK Rinex base stations == For the UK Rinex stations, the position is provided as Earth-centered Cartesian coordinates (XYZ) in the ETRS89 datum (directly compatible with WGS-84, just more exacting). As they're compatible, these coordinates just need to be converted to WGS-84 lat/longs for POSGPS. If we were coming from or going to a different datum/coordinate system (e.g. OS National Grid), we would need to do a coordinate transformation rather than conversion - this is complicated! For the O/S UK GPS network (Rinex format files), the .07o file has a header like this: {{{ 2.1 OBSERVATION DATA G (GPS) RINEX VERSION / TYPE GPServer 2.50 2620 Rinex Merge 11-May-07 08:03:46 PGM / RUN BY / DATE NEOT MARKER NAME MARKER NUMBER National GPS Network Ordnance Survey OBSERVER / AGENCY 0036227 LEICA SR530 4.20 REC # / TYPE / VERS 0 RCV CLOCK OFFS APPL 102098 LEIAT504 LEIS ANT # / TYPE 3918702.4172 -7624.0107 5015612.3424 APPROX POSITION XYZ 0.0000 0.0000 0.0000 ANTENNA: DELTA H/E/N 1 1 0 WAVELENGTH FACT L1/2 5 C1 P2 L1 L2 D1 # / TYPES OF OBSERV 1.000 INTERVAL 2007 5 10 9 0 0.0000000 GPS TIME OF FIRST OBS The APPROX POSITION XYZ coordinates are NOT APPROXIMATE COMMENT APPROX POSITION XYZ replaced by precise ETRS89 values COMMENT END OF HEADER }}} Note the `ANT # / TYPE` line and the `ANTENNA: DELTA H/E/N` for antenna details. The `APPROX POSITION XYZ` is the precise ETRS89 X,Y,Z location (see COMMENT sections to confirm this it says it's precise). This must be converted to a WGS-84 lat/long: 1. Go to http://www.ordnancesurvey.co.uk/oswebsite/gps/information/coordinatesystemsinfo/gpsspreadsheet.html and get the coordinate conversion spreadsheet (or see attachment) 1. Enter the coordinates from the `APPROX POSITION` field in the .07o file into the XYZ fields on the Enter Coords here sheet, clearing the other fields 1. Check the constants are set for WGS-84 1. Take the lat/long/ellipsoidal height from the ''XYZ to lat,long,H'' sheet and enter into POSGPS (you may want to save these as a favourite too) ----------- Todo: add in detailed notes from Applanix training course