STONEX R60 - Appendix; Atmospheric Correction

Stonex R60 – User Manual 44
11. Appendix
11.1. Atmospheric Correction
The distance results measured by the instrument are correct only when corrected by the atmospheric
correction value of ppm (mm/km, 10
-6
). This scale correction value is calculated from the local
meteorological parameters entered at the time of measurement. The atmospheric correction is related
to factors such as atmospheric pressure and temperature.
For high precision distance measurements, the atmospheric correction must be accurate to 1ppm，the
relevant meteorological parameters must be re-determined at the time of the distance measurement.
The air temperature must be accurate to 1°C and the atmospheric pressure to 3hPa. The prevailing
atmospheric parameters are entered into the instrument and the atmospheric correction for the distance
measurement is automatically calculated.
The instrument default parameters：
Air temperature 20 ℃
Atmospheric pressure 1013.25 hPa
Atmospheric correction 0 ppm
Atmospheric correction formula:
kPT ＝ 279.097 - 0.29528 × P / (1＋0.0036 × T)
kPT: atmospheric correction (ppm)
P: pressure (hPa)
T: temperature (℃)
SD = SD
0
× (1 + kPT)
SD
0
: original slope distance
SD: corrected slope distance
Atmospheric correction values can be conveniently found on the atmospheric correction chart below.
The temperature is read on the horizontal axis of the chart and the pressure on the vertical axis, the
value on the diagonal of its intersection is the atmospheric correction value.