Using NTRIP Corrections with Free CORS Services — Step-by-Step Setup

Not every GNSS surveyor wants to invest in a full base station. Thankfully, free CORS (Continuously Operating Reference Stations) networks offer high-quality RTK corrections via NTRIP, often for no cost. This article shows how to set up NTRIP corrections using free CORS services with your GNSS receiver.

🌐 What is NTRIP?

NTRIP (Networked Transport of RTCM via Internet Protocol) is a way to deliver real-time correction data from a CORS server over the internet to your GNSS rover. With a stable connection, your receiver can achieve centimeter-level accuracy using data from a remote base.

🔧 What You’ll Need

• 📱 Android phone or tablet with internet access
• 📡 GNSS receiver that supports NTRIP corrections
• 📶 SIM card or Wi-Fi hotspot (to access the internet in the field)
• 🧭 Survey app (e.g. FieldGenius, ReachView, Survey Master, etc.)
• 🗂️ Free CORS NTRIP account (registration may be required)

📝 Step-by-Step Setup Guide

1. Register for a Free CORS Account

Many countries offer free access to a CORS network. Here are a few examples:

• 🇺🇸 USA: UNAVCO, NGS OPUS, or state-run networks like NYSNet, VRSNow (some require approval)
• 🇮🇩 Indonesia: BIG CORS (cors.big.go.id)
• 🇩🇪 Germany: SAPOS (for academic use)
• 🌎 Others: Search “Free CORS + your country”

After registration, you’ll receive:

• 📍 NTRIP Caster URL (e.g. cors.big.go.id)
• 📞 Port number (e.g. 2101)
• 👤 Username
• 🔐 Password

2. Configure NTRIP in Your Survey App

• Open your GNSS or survey app (e.g., FieldGenius, Emlid Flow, SurPad)
• Navigate to GNSS or RTK settings → choose NTRIP Client
• Enter the following:

Caster: cors.big.go.id  
Port: 2101  
Username: your_username  
Password: your_password  
Mountpoint: Select based on your location (e.g., CORS-ID-SMG1)

Once connected, your receiver will start receiving correction streams. You’ll notice status change from Single to FLOAT then to FIXED.

📍 Tips to Improve NTRIP Performance

• 📶 Ensure stable internet (use SIM card with strong signal)
• 📐 Choose mountpoint closest to your survey area
• 🧭 Use multi-frequency GNSS receiver for faster fix
• ⚠️ Avoid interference from trees, buildings, and power lines
• 🔁 Restart corrections if stuck on FLOAT for too long

📸 Visual Setup Diagram

Ask if you’d like an illustrated connection flow showing GNSS → Phone → CORS server via NTRIP.

🛠️ Troubleshooting Common Issues

• 🔐 Login Failed? — Check your username/password
• 🌍 Can’t connect? — Verify internet access and port number
• ❗ No FIX? — Check satellite visibility and mountpoint

🙋 Want Preconfigured RTK Kits?

We supply GNSS receivers pre-configured for free CORS networks — ready to survey out of the box. Save time and avoid errors.

🛒 Browse RTK Survey Kits

Next article: “How to Use Your GNSS Receiver as a Base Station for Local RTK”