APPLICATION OF GPS TECHNOLOGY TO ARCHAEOLOGY GROUP PROJECT

STANFORD PROJECT PROJECT AREA:CHAVIN DE’ HUANTAR GOALS  TO INTERPRET THE SITE’S ARCHEOLOGICAL HISTORY THROUGH PRECISE MAPPING  TO CREATE A THREE DIMENSIONAL MODEL,GEOREFERENCED COMPUTER MODEL OF THE ARCHEOLOGICAL SITE

OBJECTIVES OF USING GPS THE MINI- PROJECT WAS TO DEFINE THE RELATIONSHIP BETWEEN THE LOCAL SITE GRID AND THE UTM GRID SYSTEM GATHER POSITIONS FOR CREATION OF TOPOGRAPHIC MAPS

INITIAL SETUP OF BASE STATION SETTING UP OF BASE STATION  CHOSEN IN SUCH A WAY TO GET A CLEAR VIEW OF THE SKY  BASE STATION WAS A 12-CHANNEL,L1,C/A-CODE CARRIER TRACKING GPS  BASE STATION WAS REFERENCED USING BASE STATION FILES FROM GEOGRAFI’CO NACIONAL DE’ PERU  POSITIONAL ACCURACY OF 0.25M –HORIZONTAL AND 0.5M-VERTICAL WAS ACHIEVED

ROVER RECEIVER ROVING RECEIVER WAS A 12- CHANNEL,L1,C/A-CODE AND CARRIER PHASE UNIT WITH A HANDHELD DATALOGGER CARRIER PHASE TRACKING GIVES THE REQUIRED PRECISION FOR THE LOCATIONS IN THIS PROJECT BASICALLY WAS OPERATED AT VERTICAL SETTING OF 2M.EXTENSION RODS ARE USED IN CASE OF INCREASED HEIGHTS

DATA COLLECTION BOTH THE BASE STATION AND ROVER RECEIVER COLLECTED DATA AT THE RATE OF 60 POSITIONS(min) AT 5sec INTERVAL CARRIER PHASE PROCESSING MODE WAS USED TO CALCULATE THE POSITIONS OF THE LOCATIONS A HORIZONTAL ACCURACY OF cm WAS ACHIEVED AT 95% CONFIDENCE LIMIT AT THE SAME CONFIDENCE LEVEL A VERTICAL PRECISION OF 7-10cm WAS ATTAINED

OPERATING MODES KINEMATIC IN AREAS WERE GRASS WAS SHORT KIMENATIC MODE WAS USED TO MAP CONTOURS STATIC TO WORK IN AREAS WERE GRASS WAS TALL AND ALSO TO RECORD POSITIONS FOR CONTOURS NOTE:THIS IS DONE FOR TOPOGRAPHIC MAPPING

POST PROCESSING THE GPS SOFTWARE THAT WAS USED PROCESSED DATA FIRST AND THEN CARRIER PHASE PROCESSING TO RESOLVE FOR INTEGER AMBIGUITY ON-THE-FLY ALGORITHM WAS USED.

LOCAL GRID SYSTEM THE LOCAL GRID SYSTEM WAS ESTABLISHED WITH A NETWORK OF SIX CONTROL POINTS USING A SPECIAL SOFTWARE THE LOCAL COORDINATE SYSTEM WAS ORIENTED TO THE NORTH

RELATING THE LOCAL GRID TO UTM GRID THREE MORE ADDITIONAL BUT TEMPORARY CONTROL POINTS WAS ESTABLISHED TO ACCOMPLISH THE TRANSFORMATION,THE THREE TEMPORARY CONTROL POINTS WAS RECORDED ON THREE DIFFERENT DAYS TO GIVE ENOUGH REDUNANCY ONE OF THE PERMANENT CONTROL POINTS OF LOCAL GRID SYSTEM WAS ALSO OBSERVED

DATUM TRANSFORMATION USING LEAST SQUARES APPROXIMATION THE GPS SOFTWARE COMPUTES THE TRANSFORMATION PARAMETERS AVERAGE TWO DIMENSIONAL RESIDUAL OF 1.9cm WITH STANDARD DEVIATION OF 0.8cm AVERAGE THREE DIMENSIONAL RESIDUAL OF 2.2cm WITH A STANDARD DEVIATION OF 0.9cm

PRECISION OF GEOMETRY USING 22 OBSERVATION VECTORS FROM BASE STATION TO CONTROL POINTS  AVERAGE HORIZONTAL PERCISION OF 1.8cm WITH STANDARD DEVIATION OF 0.29cm WAS ACHIEVED AT 95% CONFIDENCE LIMIT  AVERAGE VERTICAL PRECISION OF 6.06cm WITH A STANDARD DEVIATION OF 1.64cm WAS ATTAINED AT THE SAME CONFIDENCE LIMIT