One of the problems when it comes to settle a RTK differential configuration (base + rover) is to be able to send the correction data from the base to the rover. Since communication is rather limited, an NTRIP network can then be implemented.
THE NTRIP PROTOCOL
Network transport of RTCM frames via the Internet Protocol (NTRIP) is a protocol for broadcasting differential GPS data (DGPS) over the Internet according to the specification published by RTCM. NTRIP is a generic, stateless protocol based on HTTP / 1.1 (Hypertext Transfer Protocol) and enhanced for GNSS data streams. It was developed by the German Federal Agency for Mapping and Geodesy (BKG) and the Department of Computer Science at the University of Dortmund.
Networked Transport of RTCM via Internet Protocol enables the mobile RTK GPS receiver (rover) to access data from the RTK base station over the internet to achieve 1cm accuracy.
How does NTRIP work?
NTRIP consists of two pieces of software which communicate over the internet. The server side runs NTRIP Caster software. The rover side runs the NTRIP Client software. The NTRIP caster is responsible for receiving the data stream from the base receiver and rebroadcasting it over a specified TCP (Transmission Control Protocol ) port.
Let’s say that a caster is configured to broadcast over TCP port 1000 and the external IP address of the computer running the caster software is 22.214.171.124. On the rover side, the NRTIP client software is told to connect to the server at IP address 126.96.36.199 on port 1000. This is usually done by the user in a simple form which makes it easy to change servers easily. Once the NTRIP client connects to the NTRIP caster the data stream is sent to the rover receiver via serial, Bluetooth, USB, etc.
The benefits of using NTRIP over radio setups
- Less equipment to carry in the field. Almost all data collectors, smartphones, and computers have the capability to connect to the internet even in a field setting. This is usually done through a SIM card.
- No license required (some radios require licensing).
- Mitigate the chance of radio interference.
- No limitation on communication range. 900MHz, VHF, and UHF radios have a limited range.
- Its application is not limited to one particular plain or coded stream content; it has the ability to distribute any kind of GNSS data.
- It has the potential to support mass usage; it can disseminate hundreds of streams simultaneously for up to a thousand users when applying modified Internet Radio broadcasting software.
- Regarding security needs,
The limits of using NTRIP:
- It requires the work area to be in range of cellular service for receiving corrections data via the Internet.
HOW TO USE NTRIP WITH DROTEK GPS RECEIVERS?
NTRIP allows a greater flexibility in terms of delivery port given that today all cellular terminals are 4G compatible. As a result, a simple mobile phone becomes an internet relay available on any type of terrain for passing RTCM correction data to any rover. In addition to its relative simplicity of use, unlike 433MHz radios that can only communicate point-to-point, this configuration has the advantage of being able to send the same data of corrections to several rovers at once.
If you want to get a step by step tutorial for using this protocol with our gnss receivers, you can follow this link and access our tutorial platform.