ION GNSS 2005

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Data Formats and Transport ProtocolsFor
Real-Time GNSS Georg Weber Federal Agency for
Cartography and Geodesy (BKG) Frankfurt,
Germany AFREF Technical
Workshop, 9-13 July, 2006, Cape Town
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(No Transcript)
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Satellite Clocks
Real-Time GNSS Product Areas
Satellite Orbits
Ephemerides
Raw Streams
Troposphere
RTIGS Streams
Ionosphere
RealTime GNSS Engine
Space Weather
DecodingSync
Conversion Products
Satellite Health
Interference
RTCM 3 Streams
Geodynamics
RTCM 2.x Streams
Natural Hazards
Networked DGNSS
Networked RTK
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Efforts for Station Upgrade from Post-Processing
to Real-Time

• Implementation costs for a post-processingreferen
  ce station 40,000?
• Upgrade to real-time only adds monthly
  communication costs

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Yearly Growth of Number of Cell Phone Users
58 (87)
Africa
Asia
34 (31)
World-wide
29 (46)
26 (62)
Europe
America
23 (45)
Oceania
21 (48) (Prepaid)
Source ITU Statistics, 1999 2004
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Weaknesses

• Telecom liberalization? Phone charges still high.
• Cape Town's February power blackouts.
• However
• "Accelerated and Shared Growth InitiativeSouth
  Africa" (Asgisa) says Sustained yearly GDP
  growth of 6 per cent for the coming 5 years.
• Gautrain Rapid rail network connecting
  Johannesburg and Pretoria ( 3.2bn).
• ......

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Data Format Transport Protocol
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Data Formats

• RTCM, Version 2.x and 3
• RTCA, EGNOS WAAS
• RTIGS
• BINEX
• RINEX
• SP3
• Open vendor formats, like CMR
• Protected vendor formats, like MBEN
• Etc, etc

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RTCM Data Formats

• RTCM 2.0 Pseudo Range Corrections, DGPSMT 1, 3,
  9, Meter Level Accuracy
• RTCM 2.1 and 2.2 Carrier Phase Data, RTKMT 18,
  19, 20, 21, Centimeter Level Accuracy
• RTCM 2.3 Adds GLONASS, RTKMT 18, 19, 20, 21,
  Centimeter Level Accuracy
• RTCM 3.0 Bandwidth Reduction, RTKMT 1004 etc,
  Centimeter Level Accuracy

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Radio Technical Commission for Maritime Services

• Founded 1947 as U.S. State Department Advisory
  Committee
• Now an independent membership organization
• Supports development of standards and regulations
• IMO, ITU, IEC, ISO
• Runs Special Committees and Working Groups
• ? SC-104 Differential Global Navigation
  Satellite Systems ? Working Group Internet
  Protocol
• Other Special Committees SC-109, 101, 110, 112,
  117, 119

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IP Streaming - Transport Protocols

• Plain TCP or UDP
• RTIGS on top of UDP
• NTRIP on top of TCP or UDP

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Networked Transport of RTCM via Internet Protocol
(Ntrip) - Based on HTTP
- Handles Metadata
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Meta-data
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Ntrip - Characteristics

• Http Easy to implement, usually not blocked by
  firewalls
• Distribution of any kind of GNSS data
• Mass usage Disseminating hundreds of streams
  simultaneously for a few thousand users when
  applying modified Internet Radio broadcasting
  software
• Security Stream providers and users not in
  contact
• Streaming over any (mobile) IP network

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September 2004 Ntrip Vers. 1.0 becomes RTCM
Standard
Selection of devices supporting Ntrip
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Ntrip Version 2.0

• Full HTTP compatibility (proxy server)
• UDP Unicast Transport for Client-Caster
  communication
• Real-Time Streaming Protocol (RTSP)on top of TCP
  for stream control
• Real-Time Transport Protocol (RTP)on top of UDP
  for data transport

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Data Format Transport Protocol
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RTIGS-NTRIP www.igs-ip.net Pilot Project
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AFEF Data PolicyRecommendation

• Open data policy
• Not handling classified data

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• AFREF Reference StationRecommendation
• Establish new stations with real-time
  capability whenever communication available
• Upgrade existing stations to real-time
• Support formats accepted by clients
• Generate high-rate data streams
• Upload streams to (next) Ntrip Broadcaster
• Monitor stream flow and content
• Assist existing real-time services
• Participate in global stream exchange

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AFREF Internet Broadcast Recommendation
Administration
Observations
Products
Reference Receiver
Rover Receiver
Reference Receiver
Rover Receiver
Reference Receiver
Rover Receiver
WAAS Receiver
NtripClient
NtripServer
NtripTracker
NtripTracker
NtripClient
NtripServer
NtripClient
NtripServer
NtripTracker
NtripServer
System Operator
System Operator
System Operator
DSL
Mobile IP
DSL
Mobile IP
DSL
DSL
Mobile PI
Mobile PI
Mobile IP
DSL
Mobile IP
DSL
DSL
Internet
Primary NtripCaster
Backup NtripMonitor
Backup NtripCaster
Primary NtripMonitor
Primary Conversion I
Primary Conversion II
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Ntrip StreamsEurope
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http//www.igs-ip.net/home
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(No Transcript)
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Ntrip Tools

• Ntrip Client
• Windows GNSS Internet Radio
• Windows CE PocketPC 2003 GNSS Internet Radio
• Linux Plain Example Program, GNU GPL
• Linux Perl NtripClient, GNU GPL
• Palm OS Demo Example Program
• Ntrip Server
• Windows Reading from Serial Port
• Windows Command line version, reading from IP
  address/port
• Linux Reading SISNeT, TCP/UDP Port, Serial Port,
  NtripCaster, GNU GPL
• Linux Perl NtripServer, Reading from Standard
  Input, GNU GPL
• Ntrip Decoder, Converter, etc
• Windows GnssSurfer, Client Server RTCM 2.x
  Decoder, GNU GPL
• Windows RTCM 2.x DGPS/RTK Decoder, reading from
  TCP/IP Port
• Linux Stand-alone RTCM 2.x RTK Decoder, reading
  from Std. Input, GNU GPL
• Linux Multi-Stream Client and RTCM 2.x to RINEX
  Converter, GNU GPL
• Linux Client and RTCM 3 to RINEX Converter, GNU
  GPL
• Plus variety of commercial Ntrip supporting hard
  and software products

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Sharing Real-Time GNSS Efforts
Benefits http//www.igs-ip.net/home http//igs.
bkg.bund.de/index_ntrip.htm igs-ip_at_bkg.bund.de