After compensation ( 2000S ~ 3600S ), several straight line segment is used to assess precision of OD . The research results that distance difference measurement of OD and DGPS is only 0.4m ( 1 σ) .
经补偿后（2000秒以后至3600秒）选若干直线段来评价里程的测定精度，结果表明里程仪与DGPS的测距差仅0.4m（1σ）。
3600s