When you set up your laser tracker you'll see two values labeled L and T on a screen. This article explains what they mean, where to find them, and how they affect whether the system can use 2D stationing.
Quick answer: L is longitudinal tilt and T is transverse tilt — the two directions the tracker can lean away from level. The lower the numbers, the more level the tracker. When both L and T are below 90, the tracker is level enough for 2D stationing (on Radio 2 setups only — see below).
Where you see the L and T values
Which screen shows the values depends on your tracker:
| Tracker | Radio | Where the L / T values appear |
|---|---|---|
| AT930 | Radio 1 | On the tracker controller screen (the leveling page) |
| AT930-NRT | Radio 2 | On the Radio 2 screen |
| AT500 | Radio 2 | On the Radio 2 screen |
What L (longitudinal) and T (transverse) mean
Both values measure how far the tracker is leaning away from perfectly level, in two different directions:
- L — longitudinal tilt is the forward/backward lean (pitch).
- T — transverse tilt is the side-to-side lean (roll).
A perfectly level tracker reads 0 for both. The bigger the number, the more the tracker is tilted in that direction.
The numbers are not degrees or radians
The L and T values are display units, not degrees and not radians. 0 means the tracker is perfectly level, and lower is always more level. The scale is proportional, so you can convert any reading to degrees of tilt: a value of 90 equals 0.258°, which works out to roughly 0.00287° per unit.
| L or T value | Approx. tilt |
|---|---|
| 0 | 0° (level) |
| 30 | ≈ 0.086° |
| 45 | ≈ 0.129° |
| 60 | ≈ 0.172° |
| 90 | ≈ 0.258° (2D stationing cutoff) |
| 120 | ≈ 0.344° |
| 180 | ≈ 0.516° |
Why the L and T values matter: 2D stationing
Dusty picks the best stationing method for your setup automatically. When the tracker is very close to level, the system can use 2D stationing, which ignores small vertical (Z) differences and projects the layout straight down onto the floor — generally more accurate and reliable in field conditions.
The tracker is level enough for 2D stationing when both L and T are below 90 — that is, less than 0.258° of tilt. If either value is 90 or higher, the tracker isn't level enough and the system falls back to 3D stationing.
Important — 2D stationing requires Radio 2. Getting L and T below 90 only enables 2D stationing on the AT500 and AT930-NRT (both Radio 2).
How to lower the L and T values
If your L or T values are 90 or higher and you want the tracker level enough for 2D stationing:
- Adjust the tripod legs to bring the tracker toward level, watching the L and T values as you go.
- Make sure the tripod is on stable, firm ground and fully tightened.
- Re-check the values after any adjustment — both should read below 90.