How do I calibrate the ATR on a Leica total station?

Navigate to Menu → Instrument → Adjust → ATR. Set up a stationary prism at 30–50m in open conditions. Follow the on-screen steps to measure in Face 1 and Face 2. The instrument computes and stores the ATR correction offset automatically.

How often should I calibrate Leica ATR?

Calibrate the ATR at the start of each project and after any shock, transport, or significant temperature change. For high-precision work, daily ATR calibration checks are recommended. The process takes about 5 minutes.

Quick Answer

What is the ATR horizontal tracking error on a Leica total station?

The ATR horizontal tracking error on a Leica total station means the Automatic Target Recognition system has failed to lock onto or maintain horizontal track on the prism during measurement or robotic operation. The ATR uses a CCD sensor and infrared laser to detect and follow the prism — a horizontal tracking error indicates the prism signal cannot be acquired or tracked in the horizontal direction. The instrument requires re-acquisition or ATR recalibration.

Leica Total Station ATR Horizontal Tracking Error: What It Means and How to Fix It

Q: What is the ATR horizontal tracking error on a Leica total station?

The ATR horizontal tracking error means the Automatic Target Recognition system cannot lock or maintain horizontal track on the prism. Causes include ATR calibration drift, multiple prisms in view, prism moving too fast, or ATR sensor issues.

Applies to: Leica TS06, TS09, TS11, TS15, TS16, MS50, Nova TS60 (all models with ATR)

What Is the ATR Horizontal Tracking Error?

Leica's Automatic Target Recognition (ATR) is a key feature in all motorized Leica total stations. The ATR uses a separate infrared laser diode and a high-resolution CCD sensor to detect the prism's position within the field of view, then drives the servo motors to precisely aim the crosshair at the prism center — independently of the telescope optics.

An ATR horizontal tracking error means the ATR system specifically cannot maintain lock in the horizontal (azimuth) direction. This can occur during initial lock acquisition (the ATR detects the prism but cannot resolve horizontal position) or mid-tracking when the horizontal component of the prism's position jumps out of the ATR's active tracking range. Distinguishing a horizontal ATR error from a general lock failure helps diagnose whether the issue is with the horizontal servo, the ATR sensor alignment, or the ATR calibration.

Common Causes of ATR Horizontal Tracking Error

ATR calibration drift — the ATR offset from the line of sight has drifted beyond tolerance, causing systematic horizontal aiming errors
Prism moving faster than the horizontal servo can track — rapid lateral movement causes the ATR to lose the prism horizontally
Multiple prisms or reflectors in the field of view — ATR locks onto the wrong target or oscillates between two prisms
ATR CCD contamination — dust or internal contamination on the ATR sensor causes horizontal bias
Horizontal servo weakness — the horizontal drive motor cannot respond quickly enough to ATR correction signals
ATR illumination failure — the infrared LED used to illuminate the prism for ATR detection has partially failed, causing weak or asymmetric return signals
Long-range degradation — at the limits of ATR range (800m+), horizontal noise increases and tracking becomes unreliable

How to Fix Leica ATR Horizontal Tracking Error — Step by Step

Power cycle the instrument and attempt re-acquisition. Some horizontal ATR errors are transient and clear on restart.
Perform ATR calibration from the Leica menu: Menu → Instrument → Adjust → ATR (or Check/Adjust → ATR depending on firmware). Use a stationary prism at 30–50m for the calibration target.
Verify only one prism is in the instrument's field of view during ATR operation. Remove or shield any nearby reflectors or prisms that could cause false lock.
Check that the prism face is directed toward the instrument. The ATR works best when the prism is aimed within ±10° of the instrument direction for flat prisms.
Reduce prism movement speed if the error occurs while tracking a moving prism. The ATR tracking rate has limits — slower movement allows more reliable horizontal tracking.
Clean the objective lens. Even light contamination on the external optics can degrade ATR signal quality.
If the ATR calibration offset is large (>30″) or returns immediately after calibration, the ATR CCD or illumination LED may need service.
Check horizontal servo response: command a 90° turn via the servo menu. If the servo moves sluggishly or stutters, servo service is needed alongside ATR diagnosis.

ATR Calibration — What It Does

The ATR calibration procedure measures the offset between where the ATR detects the prism center and where the telescope crosshair is actually pointed. This offset — the ATR correction value — is stored and applied to all ATR-aimed measurements. When this value drifts (from temperature, shock, or aging), ATR measurements become systematically biased. Regular ATR calibration (at the start of each project) maintains sub-arcsecond ATR accuracy.

When to Contact Service

If ATR calibration cannot converge to a stable offset value, if the ATR horizontal error recurs immediately after calibration, or if ATR calibration requires corrections exceeding 60″, contact an authorized Leica Geosystems service center. ATR CCD replacement and LED service require factory tooling.

Related Leica Errors

Leica Total Station Tilting Axis Error | Leica Total Station Error E01 | Leica Total Station Error E03

Running Leica total stations? Gradelog provides AI-powered troubleshooting, ATR calibration tracking, and service history. Free to start at gradelog.com.