Global Navigation Satellite System (GNSS) data can be broadcast in real-time over the open Internet using the "Networked Transport of RTCM via Internet Protocol" (Ntrip) dissemination technique. In this context, the purpose of so-called Ntrip Broadcasters is to split data streams coming in from GNSS Reference Stations (Sources) for many simultaneously listening Clients. Ntrip Broadcasters do not alter the data. The communication between Sources, a Broadcaster, and its Clients is done through HTTP. Ntrip supports the dissemination of any GNSS data stream (GPS, GLONASS, Galileo, EGNOS, WAAS etc.) that needs 0.2 to 10 Kbit/s transmission rate and carries e.g.
Ntrip Broadcasters are currently installed world-wide to disseminate GNSS data in real-time. Visit www.rtcm-ntrip.org for a list of all known installations. Information about existing resources is available as a Broadcaster Distribution map, a Stream Distribution map, and a Stream Table.
For receiving data streams in real time you may use the BKG Ntrip Client (BNC). This is a multi-stream client designed to run on a PC or Laptop. It can retrieve data from any Ntrip supporting Broadcaster. The program handles the HTTP communication and transfers received GNSS data to a serial or IP port feeding networking software or a DGPS/RTK application.
BKG is especially engaged in operating broadcasters for EUREF, IGS and EGNOS handling several hundred incoming GNSS data streams in support of several thousand simultaneously listening clients. Our Broadcaster software is derived from the ICECAST Internet Radio under GNU General Public License.
The Broadcaster function is continuously monitored by an alarm system that generates "Notice Advisories to Broadcaster Users" (NABU's). If a data stream is unavailable for several minutes due to any reason, the monitor system generates a NABU message and sends it by e-mail to the affected stream provider. An additional message is sent when the stream becomes available again. All NABU messages are stored in a NABU Archive. Daily-generated Outage Graphics as well as daily and monthly-generated Outage Tables show the overall availability of data streams.