Topcon E02 Error: What It Means and How to Fix It

Applies to: HiPer SR, HiPer HR, HiPer II GNSS receivers

What Does E02 Mean?

E02 PDOP High on Topcon GNSS receivers means the Position Dilution of Precision (PDOP) has exceeded the quality threshold configured in the receiver or field software. PDOP is a dimensionless measure of satellite geometry quality — a PDOP of 1.0 is perfect geometry, while PDOP values above 6.0 indicate poor geometry that significantly degrades position accuracy.

When satellites are clustered in one region of the sky (common near the horizon in obstructed locations), the geometry is poor and PDOP rises. Even if the receiver has enough satellites for a solution, a high PDOP means the computed position has larger uncertainty than normal.

Topcon receivers and MAGNET Field typically flag PDOP above 4.0-6.0 as a warning condition. At PDOP above 8-10, most survey standards consider positions unreliable.

Common Causes of E02

• Satellites clustered in one sky quadrant — nearby obstructions block satellites in other directions, degrading geometry
• Working in an urban canyon where only a narrow strip of sky is visible
• Time-of-day geometry — satellite constellations rotate and PDOP naturally fluctuates throughout the day
• Single-constellation mode — tracking only GPS limits satellite distribution and raises PDOP
• Elevation mask set too high — masking satellites below 20-25 degrees unnecessarily reduces the available satellite pool

How to Fix Topcon E02 — Step by Step

1. Check the PDOP value in MAGNET Field's satellite status screen. Values below 4.0 are acceptable; values above 6.0 indicate poor geometry.
2. Enable all available GNSS constellations (GPS, GLONASS, Galileo, BeiDou). Adding satellites from multiple constellations almost always improves PDOP.
3. Reduce the elevation mask angle. If it is set above 10-15 degrees, lower it to 10 degrees to include additional low-elevation satellites that improve geometry.
4. Move to a more open location with a better all-sky view. Even moving 5-10 meters away from a building face can bring additional satellites into view.
5. Wait for the satellite constellation to rotate. PDOP naturally cycles throughout the day — if field conditions allow, waiting 15-20 minutes often brings PDOP into an acceptable range.
6. Review the sky plot in MAGNET Field to identify which sky sectors are blocked. This helps you choose a better setup location.

When to Send It In for Service

PDOP High is almost never a hardware fault. If PDOP remains high across all sky-view locations with all constellations enabled, verify receiver firmware and constellation configuration are current.

Frequently Asked Questions

What is a good PDOP value for GNSS surveys?

A PDOP of 1.0 to 2.0 is excellent. Values from 2.0 to 4.0 are acceptable for most surveys. PDOP from 4.0 to 6.0 is marginal — reduce it if the project tolerances require it. PDOP above 6.0 is generally considered poor for precision work.

Does high PDOP affect RTK fixed accuracy?

Yes — even with an RTK fixed solution, high PDOP multiplies the baseline position uncertainty. In a fixed solution at PDOP 8.0 vs PDOP 2.0, the expected position error is approximately 4 times larger. Always note PDOP when evaluating measurement quality.

Will the receiver warn me before PDOP gets too high?

MAGNET Field displays a PDOP warning when the configured threshold is exceeded (default is typically 6.0). You can configure the PDOP warning level in the MAGNET Field project settings.

Related Topcon Error Codes

Topcon GNSS E01 No Fix | Topcon GNSS E03 Base Not Connected