What is NTRIP, NTRIP Client and a NTRIP Caster?

What is NTRIP
NTRIP stands for Networked Transport of RTCM data via Internet Protocol.
NTRIP client is a program. A program that takes care (in case of an RTK NETWORK or DGPS) of the transmission of an NMEA message. It also takes care of receiving RTCM corrections which are transmitted to the GNSS receiver.

The data of reference networks or reference stations are split via an NTRIP-caster and sent over the Internet. On the user’s side (the Rover) there is an NTRIP client program, which requests data from the provider.

The NTRIP-Client program is to request a source table. What this does for you, is that it shows you a clear field of all the correction signals that a provider provides.
After you have chosen a source, you can establish a connection with it. to establish such a connection you do have to fill in an user name(ID) and of course a password. This step of the process you can see as a standerd log in procedure as often you would have to do on various platforms. After all the formalities the NTRIP- Client program takes care of sending the NMEA-messages (in case of an RTK Network or DGPS network).

NTRIP Caster
What an NTRIP- Caster does, is take data from one or multiple sources. These sources are called NTRIP-servers. It provides data to the end user(s), which we call rovers (NTRIP Clients).

NTRIP server
In essence an NTRIP server is a GNSS reference station, with a variety of quality levels combined with a layer of software. The software connects and pushes the data to a caster over a HTTP internet connection.
Most GNSS devices that are used as an reference station have a NTRIP server function built in.

The industry had opened up with the combination of the NTRIP protocol, open RTCM SC104 messages and the open RINEX file format. This combination has really expanded the field of practitioners that use precise GNSS data.
At the same time it also became a lot more affordable to get started with surveying and at the same time making use of the advantages RTK performance.