GNSS Slant Height — SurveyCalc

Units

Precision

Antenna values

Measurements

Optional. 3 measurements equally spaced around the antenna, at the start of the session and again at the end. Everything you enter is averaged.

SSlant height (m)

mark to SHMP (white line); fills S below

Before

After

Vertical height (m)

mark straight up to ARP

Before

After

RRadius (m)

centre to slant mark (SHMP)

dSHMP above ARP (m)

from antenna spec; negative if below

SSlant height (m)

taped, mark to SHMP

VVertical to SHMP (m)

HARP height (m)

vertical, mark to ARP

Enter R and S to get V. Add d to get H.

Blue border = you entered it. Green = calculated. Type over a green value to make it a known.

Phase centre

L1Correction from Antenna Reference Point (ARP) to L1 Phase Centre (m)

L2Correction from Antenna Reference Point (ARP) to L2 Phase Centre (m)

Working

S² = R² + V² (right triangle: radius across, vertical up, slant along the tape). H = V − d. Phase centre height = H + correction. Tilt of the tape from vertical: θ = atan(R / V).
Use the R, d and phase centre values from your antenna's spec sheet (NGS antenna calibrations or the manufacturer). Software that knows the antenna model normally wants the ARP height and applies the phase centre correction itself, so check which height it expects.