1. Real Time GNSS via Internet Protocol Status & Standardization
Georg Weber, Denise Dettmering, Harald Gebhard
Federal Agency for Cartography and Geodesy, BKG, Frankfurt
CGSIC 43rd Arlington, Virginia, March 10-11, 2004

2. DGPS & Internet - Classic Approach
PROVIDER
Server PC
Internet
Cellular
Phone
Network
GPRS
Modem
Client PC
DGPS
USER

3. NTRIP: Networked Transport of RTCM via Internet Protocol
GPS
PROVIDER
Server PC
NTRIP
Broadcaster
NTRIP
No direct communication between User and Provider
Only one Internet Server (Caster)
Caster works as data splitter: mass usage possible
Communication handled through HTTP-Port 80
Client PC
DGPS
USER
GPRS
Modem

4. EUREF-IP Ntrip Broadcaster
Available data streams (02/2004)
 145 real time data streams
13 networks (EUREF, IGS, CORS,...)
GPS, GLONASS, EGNOS,...
Different formats:
RTCM corrections (DGPS, RTK)
raw measurement data
RTCA
Most streams from Europe
21 from USA
1 from Chile
1 from Australia IP
Capable of handling
Up to 300 real-time data streams
Up to 1500 simultaneous users

5. Ntrip Real-Time GNSS Network, Status 040305

6. Temporal Availability
0.00
0.49
1.60 5 10 15 20 25 30 35
BUCU0
CAGZ0
GOPE0
HERT0
JOZ20
KRAW0
PENC0
Stream
Outages [%]
Network: EUREF

7. Temporal Availability
Network: EUREF January 2004
22.40
0.40
0.20
9.00
1.10
28.60 5 10 15 20 25 30 35
BUCU0
CAGZ0
GOPE0
HERT0
JOZ20
KRAW0
PENC0
mountpoint
outages [%]
All data streams: (14 networks)
more than 50% show an availability higher than 95%
32% of the data streams are available more than 98%

8. Accuracy RTK Positioning - Internet and GPRS (baseline < 1km)
=> No significant degradation of performance compared to usage of other transportation media

9. Latencies - Korrekturdaten - RTCM corrections10 20 30 40 50 60 70 80 90
100
0.5 1
1.5 2
2.5 3
3.5 4
Max. latency [sec]
Frequency [%]
Internet
DGPS data stream (without carrier phase information)
Brussels => Ntrip Caster => Frankfurt
Internet + mobile (GPRS)
Internet: 95% of latencies < 1 second
Internet and mobile phone:
5% of latencies above 2 seconds

10. NTRIP Client: „GNSS Internet Radio“
available for Windows, Windows CE, Palm, LINUX

11. Mobile Data Access GIS & DGPS:
Simultaneous Real-Time Access to Distributed Data
Compaq iPAQ Pocket PC
with „GNSS Internet Radio“
Nokia D211 GPRS modem
DGPS: 0.7 cent/min

12. Other Broadcaster Implementations
Broadcasting Network
Regional Broadcasters
Distributing the Workload
EUREF: :80
BKG: :80
IGNE: :2101
Terrasat: :8080
Thüringen: :8040
Hessen: :8080
Swisstopo: www3.swisstopo.ch:8080
Trimble DK: Makalu.GPSnet.dk:9000

13. NTRIP - Standardization
Co-operation with receiver manufacturers
Standardization process within RTCM SC-104
Working Group on „Internet Protocol“
Chair: Robert Snow, Thales
WG Members from Leica, Trimble, Ashtech, Topcon,
U.S. Coast Guard
RTCM Paper /SC
New RTCM standard hopefully within the next few month

14. Conclusion
Streaming GNSS real-time data over Internet and mobile networks becomes operational
EUREF-IP Ntrip Broadcaster providing data since several month
NtripCaster handles up to 300 streams and up to 1500 simult. users
Today: 150 real-time data streams from 16 countries
Latencies less than 1 second (2 seconds for mobile phone connections) sufficient for most applications like: real-time positioning, navigation, orbit determination
No significant degradation of performance compared to usage of other transportation media
Information on the Web
EUREF Ntrip Broadcaster:
Ntrip Format:
Download: