What is NTRIP? How is it used for RTK?

In order to acheive an accurate RTK Survey, a user will need a rover and a base which transmits GNSS corrections in real time.

When it comes to the base, there are three main options. A user can choose to use their own, local base which is located somewhere within the vacinity of where they are conducting their survey. An alternative to this is to access one remotely using technology called NTRIP.

What is NTRIP?

Originally developed by the German Federal Agency for Cartography and Geodesy in 2004. NTRIP or the Networked Transport of RTCM via Internet Protocol allows a GPS / GNSS rover to receive corrections over the internet without the need for a local base.

NTRIP consists of three parts:

1. The Base, in Emlid’s case this is a customer’s Reach RS+ or Reach RS2 set as a Base situated in a fixed, known, location.
2. The Caster, in Emlid’s case, they offer a free caster which allows a user to relay corrections from their own base to the rover.
3. The Rover, in Emlids case this could be a second Reach RS+ or Reach RS2 set as a Rover.

When carrying out a survey the rover received all the corrections in real time via the internet*.

How to Connect to NTRIP

There are a number of third party local NTRIP providers available. Some have no cost associated, however, on the whole there is often a subscription required to access their services. We encourage users to choose the service which best suits their individual requirement.

Alternatively, Emlid offer their own NTRIP caster. Designed with a user friendly interface, which allows for very easy setup.

The Advantages and Disadvantages of using NTRIP

NTRIP can be very useful for working in RTK. It does however, have its advantages and disadvantages.

Advantages:

High absolute accuracy. With corrections from NTRIP, you obtain high accuracy in your data.
No need for a local base. You can work with just a rover and still perform an accurate survey.
Fast fix. Internet connection to NTRIP helps you find the fix solution faster.

Disadvantages:

Fees. Some NTRIP networks are private, therefore a user will need to pay for using them. These costs can be pretty prohibitive.
NTRIP is dependent on the Internet. It therefore only works where there is cellular network coverage. NTRIP is unavailable where there is no cellular / internet access.