GPT-3000 SERIES - FLT Geosystems

13 CORRECTION FOR REFRACTION AND EARTH CURVATURE13 CORRECTION FOR REFRACTION AND EARTHCURVATUREThe instrument measures distance, taking into account correction for refraction and earth curvature.13.1 Distance Calculation FormulaDistance Calculation Formula; with correction for refraction and earth curvature taken into account.Follow the Formula below for converting horizontal and vertical distances.Horizontal distance D = AC(α) or BE(β)Vertical distance Z =BC(α) or EA(β)D = L{cosα–(2θ – γ ) sinα}Z = L{sinα+(θ – γ ) cosα}θ = L•cosα/2R........... Earth curvaturecorrecting itemγ =K•Lcosα/2R....... Atmosphericrefractioncorrecting itemK =0.14 or 0.2.......... Coefficient ofrefractionR =6372km.............. Radius of earthα ( or β)................... Altitude angleL .............................. Slope distance●The conversion formula for horizontal and vertical distances is as follows when correction forrefraction and earth curvature is not applied.D=L•cosαZ=L•sinαNote:The coefficient of the instrument has been set at 0.14 before shipment (K=0.14).if the "K" value is to be changed, refer to 16 “SELECTING MODE”.13-1