8

2002-2007

Today, real-time data streams are part of the EPN routine operations, see Network & Data > Data Access > Real time

EUREF - Real Time

With the increased capacity of the Internet, applications that transfer continuous data streams by IP-packages, such as Internet Radio, have become well-established services. Compared to these applications, the bandwidth required for the transmission of real-time GNSS data is relatively small. Consequently, EUREF decided in June 2002 to set up and maintain a real-time GNSS infrastructure on the Internet using stations of its European GPS/GLONASS Permanent Network EPN. Although today´s primary objective is to disseminate RTCM corrections over the Internet for precise differential positioning and navigation purposes (see Resolution), various other applications are in sight like real-time orbit determination and ionosphere or troposphere parameter estimation.

NTRIP

The service that EUREF wants to establish, called "EUREF-IP" (IP for Internet Protocol), is based on a dissemination standard, called "Networked Transport of RTCM via Internet Protocol" (Ntrip). Ntrip is a generic, stateless application-level protocol based on the Hypertext Transfer Protocol HTTP Version 1.1. It is designed to disseminate differential correction data (e.g. in the RTCM-104 format), or other kinds of GNSS streaming data, to stationary or mobile users over the Internet, allowing simultaneous PC, Laptop, PDA, or receiver connections to a broadcasting host. Ntrip supports Wireless Internet access through Mobile IP Networks like GSM, GPRS, EDGE, or UMTS because of using the TCP/IP protocol. Please visit the Ntrip homepage for further information.

EUREF-IP Network

The EUREF-IP service 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. EUREF-IP is a trial service. Data are available for test and evaluation purposes only.

NTRIP Broadcasters

The BKG operates the main EUREF-IP Broadcaster. However, the aim is to set up a well-distributed network of Ntrip Broadcasters supporting real-time GNSS applications in various regions.

Accessing EUREF-IP GNSS data streams

To receive real-time GNSS data streams needs a user registration. Authorization (user-ID and password) will be provided by the affected Broadcaster operator (see table above). Please note that data is often available for demonstration and evaluation purposes only. For receiving data streams in real time you may download software for various platforms from here.

Guidelines and Meta-data

The Guidelines for EPN stations and Operational Centres include guidelines for the EPN real-time data streams (Sections 3.3 and 3.7). They give specifications for the real-time data flow, and for the stream contents. All streams should contains full code and carrier phase observations and the streamed meta-data should be in agreement with the information given in the station site logs. Important are the station coordinates which are included in the RTCM streams. These coordinates should be given in the ETRS89 catalogue maintained by the EPN CB.

Contact

Questions or comments may be sent to euref-ip@bkg.bund.de.