mobileNtrip

NTRIP

Networked Transport of RTCM via Internet Protocol (NTRIP) is an application-level protocol that supports streaming Global Navigation Satellite System (GNSS) data over the Internet Ntrip is designed to disseminate differential correction data or other kinds of GNSS streaming data to stationary or mobile users over the Internet, allowing simultaneous connections to a broadcasting host.
Using Ntrip, it is possible to decrease GPS receivers position measurement errors (10-15 meters) to sub meter (DGPS format) or even centimeter level (RTK format) accuracy.
NTRIP is used in EUREF-IP project which is based on a number of GPS permanent stations of EUREF's EPN.
The goal of the pilot project is to evaluate and stimulate the use of the Ntrip technology. All data are sent to a EUREF Broadcaster from where they can be received by authorised users.

NTRIP Components

The Ntrip "network" consists of three types of applications namely NtripClient, NtripServer and NtripCaster ( schema).
The NtripCaster operates as a real server or splitter (HTTP), NtripClient (mobileNtrip) and NtripServer (mobileNtripServer) applications act more like clients according to the classical internet communication that is usually based on the classic server / client principle (one or more servers share resources with users within a network).
The communication between NtripServer and NtripCaster as well as NtripClient and NtripCaster is fully compatible HTTP 1.1.
In case of loosing the TCP (Transmission Control Protocol) connection between the described communicating system components (NtripServer-NtripCaster, NtripClient-NtripCaster) the involved TCP-sockets will recognize this and ensure a fully automated reconnection.
Ntrip "network" consits of NtripSources, generating DGPS and RTK datastreams at specific locations - NtripServers, transfering data from one or multiple sources to NTRIP - NtripCaster, major broadcaster, integrated between data sources and data receivers.

Mainly, NTRIP protocol is implemented in modern virtual reference systems like VRS Trimble and GNSMART GEO++ using correction data servers called iGate and GNCASTER.

NTRIP Connections

Users in the field have the choice to decide the technique for receiving DGPS or Real Time Kinematic(RTK) through the Internet. GSM, GPRS, EDGE and in future UMTS are suitable choices. Details of the various techniques are as follows:

GSM - is a public digital cellular network using techniques for multiplexing and using transmission band around 900 MHz. It is a worldwide standard. A GSM network can provide, besides telephony services, data communication in circuit and/or package mode. A more recent version uses an 1800 MHZ band (Europe) whereas a 1900 MHz access network is running in the United States.
GPRS - (General Packet Radio Service) is a global system for mobile communication that increases the channel speed from 9.600 to 14.400 bits per second (bps), adding data compression. With GPRS, mobile data transmissions can be as fast as 115.000 bps using the existing GSM base station infrastructure.
EDGE - (Enhanced Datarate for Global Evolution) is a new modulation scheme that is more bandwith efficient for the use in standard GSM networks. The modulation scheme is called 8PSK (8 Phase shift Keying modulation) and enables each pulse to carry 3 bits of information versus GPRS with 1 bit per pulse rate. Overall this enables EDGE to increase the data rate of existing GSM systems by a factor of three (384kbit/s).
UMTS - (Universal Mobile Telephone System) is seen as the third European generation of the mobile communication system. The spectrum for UMTS lies between 1900 MHz to 2025 MHz and 2110MHz to 2200 MHz. A satellite service will also be available. UMTS offers a "multimedia" choice which means in this sense a simultaneous transfer of speech, pictures and data with a maximum data rate of 2 Mbit/s. Transmission of speech and low data rate applications will continue to be carried out by GSM.

Our mobileNtrip Clients and Server applications for mobile phones give great opportunity to use the Ntrip technology with new and old types of GPS devices.

More information about Ntrip technology and EUREF-IP project you can find at following sites:
Ntrip Homepage
Ntrip documentation

Abbreviations

CSD - Circuit Switched Data
DGPS - Differential GPS
EGNOS - European Geostationary Navigation Overlay Service
EDGE - Enhanced Data for Global Evolution
GPS - Global Positioning System
GNSS - Global Navigation Satellite System
GPRS - General Packed Radio Service
HTTP - HypeText Transport Protocol
NMEA - National Marine Electronics Association
NTRIP - Networked Transport of RTCM via Internet Protocol
RTCM - Radio Technical Commission for Maritime Services
RTK - Real Time Kinematics
TCP/IP - Transmission Control Protocol/Internet Protocol
UMTS - Universal Mobile Telecommunications System
WAAS - Wide Area Augmentation System