What is the accuracy difference between Fixed and Float RTK?

Fixed RTK typically delivers ±8 mm horizontal and ±15 mm vertical accuracy. Float RTK carries ±300–1000 mm of positioning error depending on baseline length and atmospheric conditions.

Why does my RTK show Fixed but coordinates are still wrong?

Common causes are a datum mismatch (wrong coordinate system), an incorrect geoid model applied to elevation, or an antenna height entry error.

How do I know if multipath is affecting my survey?

Multipath typically shows as unstable repeated measurements — the same physical point measured three times gives results differing by 20–50 mm rather than the expected ±8 mm.

Can I survey during ionospheric storms?

RTK accuracy degrades during geomagnetic storms (Kp index above 5). For precision engineering or cadastral surveys, postpone sessions until the Kp index drops below 3.

What is the maximum reliable CORS baseline for centimetre accuracy?

Most CORS networks guarantee ±10–20 mm horizontal accuracy within 50 km of the nearest reference station. Beyond 70 km, deploy a self‑deployed base station within 15 km of the survey area.

APEKS FAQ | The Hidden Danger in Your Volume Survey: Wrong Pole Height

2025-07-11

The Hidden Danger in Your Volume Survey: Wrong Pole Height

If you're working on earthwork or asphalt paving projects（using AP10 and AP30 Laser）, you probably know how important accurate volume calculation is.

But have you ever been off by thousands of cubic meters?

It happens — and the consequences can be serious:
💸 cost overruns, ❌ disputes with clients, and 📉 damaged project credibility.

One surprisingly common reason for these large errors?
👉 Incorrect pole height.

📏 Why Pole Height Is So Critical in RTK

In modern RTK systems equipped with IMU (tilt compensation), pole height plays a more important role than many surveyors realize.

When the pole is tilted, the RTK system uses trigonometric calculations to determine the true position at the pole tip — the actual ground point you're measuring.

That means:

Vertical accuracy depends on correct pole height
But also your horizontal coordinates are affected
Any mistake in pole height will directly impact all measured point positions

Even a small error in height — say, 5 cm — can lead to significant positional shifts. And when these points are used to calculate cut/fill volumes, the final result can be off by hundreds or even thousands of cubic meters.

⚠️ Real-World Impact

For high-stakes projects like:

Road base construction
Land grading
Asphalt overlay
Excavation tracking

...a wrong pole height setting can lead to wrong billing, wasted materials, or disputes.

✅ Best Practices

Always verify your pole height before starting any survey
Use poles with clear, fixed height markings
Make it a habit: check pole height the same way you check satellite status or base connection

🧠 Final Thought

Pole height might seem like a small technical detail — but it has big consequences.

In RTK surveying, especially when working with tilt compensation and volume analysis, accuracy starts from the ground up. Literally.

Get the height right. The rest will follow.

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