TapeDrop

levelling fieldbook with tape-drop temperature & calibration corrections
NNB Survey TeamBuilt by surveyors, for surveyors
self-test…
1 — Job details (carried into the report and the StarNet .DAT header)

2 — Fieldbook
Book it exactly like the paper book: change point = F.S and the new B.S on the same row.
A run that ends back on its start point (same point name) is detected as a closed loop automatically — the closing R.L. is then the opening R.L. and this box is ignored.
How the book works
B.S
backsight — first reading after setting up the level (opens each setup)
I.S
intermediate sight — any reading between the B.S and F.S of a setup
F.S
foresight — last reading before moving the level
CP
change point — F.S and the new B.S booked on the same row
🌡 TD
tape drop — a change point read on the suspended tape instead of a staff; flag it and TapeDrop corrects the B.S for temperature + calibration
Datum
datum row — tick the Datum column to hold that row at a known R.L.; the whole run is re-datumed onto it and the opening R.L. becomes a computed value
R.L.
reduced level, computed on Process by Rise & Fall or Height of Collimation (both give identical R.L.s — the choice sets the booking columns and checks shown)
1 — Setup
2 — RAW booking sheet
Correction breakdown
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Calibration and temperature adjustment designed by Matthew Phillips.

3 — ADJUSTED booking sheet
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Workbook rule: the F.S stays exactly as read — the whole correction moves the B.S so the adjusted distance is the corrected tape length.

1 — Setup
2 — Station

Enter the height as currently computed from the UNCORRECTED tape drop.

Correction breakdown
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3 — Adjusted height
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1 — Test setup

2 — Readings
m
m
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m
3 — Result
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Balanced B.S/F.S distances cancel collimation error completely — a marginal instrument still levels correctly with equal sights.

Tapes
Selected tape (from the calibration certificate)
Nominal (m)Lab value (m)
Constants

Edits take effect when you click Apply & Save. The register is stored in THIS browser only (localStorage) — the defaults baked into this file are the four certificates from the calibration workbook.

Instruments (levels)
Selected instrument

Picking an instrument on the Fieldbook tab fills the Instrument box with "Name (S.N serial)". The register is stored in THIS browser only (localStorage).

All starter accuracy figures are verified (NA2s from the Leica manual; DNA03/LS15/DiNi confirmed 2026-07-16). Old warning kept for edited entries: figures you type yourself have NOT been verified against datasheets — check the datasheet or calibration certificate of the actual instrument before relying on a figure.

A new TapeDrop version is ready.