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 | CORS/NTRIP: How It Works and When to Switch to Traditional Radio Mode

2025-07-01

CORS/NTRIP: How It Works and When to Switch to Traditional Radio Mode

If you're using high-precision RTK devices like the AP10, AP30 Laser, or AP50 Vision in your daily work, chances are you're relying heavily on CORS or NTRIP networks. These network-based correction services are widely used across the surveying and mapping industry for their convenience and real-time performance. But have you ever stopped to think about how they actually work — and when they might not be your best option?

Let's break it down.

What is CORS?

CORS stands for Continuously Operating Reference Service. Think of it as a nationwide network of base stations. Instead of setting up your own base and radio every time you survey, you can simply connect to an existing station through the internet. With just a login and password, you're good to go — anytime, anywhere.

This system has revolutionized GNSS surveying by offering more flexibility and reducing the need for extra hardware in the field.

Why Some Users Are Running Into Issues

However, in recent years, users have increasingly reported issues with signal stability when using network CORS. The reason?
One major factor is ionospheric interference — irregularities in the Earth's upper atmosphere that can distort GNSS signals, especially during high solar activity.

If you've been experiencing:

Unstable or dropping corrections
Inconsistent accuracy
Delays in real-time positioning

…it's very likely that ionospheric conditions are to blame — and this tends to impact network-based solutions like CORS/NTRIP more than local setups.

When to Switch Back to Traditional Radio Mode

In these cases, it might be time to reconsider a traditional setup:
One base + one rover, connected by UHF or LoRa radio.

Unlike CORS, a local base station is not dependent on internet connectivity or public infrastructure. It also operates within a much smaller area, making it less vulnerable to ionospheric disturbances.

If your job site is in a region with frequent CORS signal issues, or if you require ultra-stable corrections for high-precision work, going back to the tried-and-true base and rover setup could be your best bet.

Final Thoughts

CORS is a powerful tool — but like any technology, it's not perfect for every situation. Understanding when to use CORS/NTRIP and when to rely on local radios can make a big difference in the efficiency and accuracy of your work.

Need help choosing between the two? Our team is here to guide you through the best setup

Click the link below to send an inquiry and learn more about our products.
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