1. Radio Technical Commission for Maritime Services
The State and Status
Special Committee – 104
20 March, 2014
NOAA March 2014
NOAA / NGS RTN Webinar
Kendall Ferguson
Hemisphere GNSS, Senior Principal Design Engineer
RTCM, SC-104 Chair & Board of Directors
Stafford, VA USA

2. Presentation Outline Question Often Asked
Why is RTCM, an apparent maritime-based organization, involved in carrier-based real-time GNSS provider networks?
Existing Standards: State and Work In Progress
The current standards
Work in progress
New work on the horizon
Summary

3. Two Main Message Standards
RTCM 2.3 (RTCM )
Codephase Differential Corrections
Primarily L1-Only, GPS-Only (though there is some support for GLONASS)
For SOLAS applications
Message format developed with primary communication link layer in mind
MF/LF Band at bps
Typical Accuracies < 1 m
Yes, RTCM support carrier applications but these are not SOLAS
RTCM 3.2 (RTCM )
Carrier and Code Differential Corrections for High-Precision
For RTK, Network RTK, and PPP-type applications
Recently modernized with, so called Multiple Signals Messages (MSM), for generic inclusion of new constellations and signals
MSM Currently supports GPS, GLONASS, Galileo, QZSS, BeiDou, SBAS
Though some work still in progress for newer constellations and signals
Message structure designed with OSI 7-layer architecture in mind

4. Standards Work In Progress
RTCM (i.e., Version 2.3)  Version 2.4
Multi-GNSS/Multi-Frequency (i.e., DGNSS).
Via new generic messaging approaches (e.g., Type 41 and 42).
Potential for 2 dm 2 σ (at max broadcast range).
Supports Legacy Message Interleave (e.g., Type 1 and 9).
Recommending Retirement of Types 18-21
RTCM (i.e., RSIM 1.2)  RSIM 1.3
Defining Reference Station (RS), Integrity Monitor (IM), Control Station (CS) and Transmitter (TR) Performance, Functions, and Messaging for SOLAS DGNSS Applications.
Modernizing from L1 GPS only to Multi-GNSS/Multi-Frequency
Adding further Alarm Attributes to Aid in Monitoring and Reporting of Alarm Conditions
Reduce Load on Control Station Operators
Speed System/Component Failure Detection and Recovery

5. Standards Work In Progress (continued)
RTCM 3.2
Version 3.2 Published February 1, 2013
Mostly to collect the numerous revisions to Version 3.1
These 3.1 updates include:
First Multiple Signals Messages (MSM)
First State Space Representation (SSR) Messages
MAC and FKP Messages
Amendment 1 (Published July 12, 2013)
Added BeiDou Multiple Signals Messages (MSM)
Added Galileo F/Nav Ephemeris Message
Amendment 2 (Published Nov 7, 2013)
Added QZSS Multiple Signals Messages (MSM)
Added QZSS Ephemeris Message

6. Standards Work In Progress (continued)
RTCM 3.2 (Work In Progress)
State Space Representation (SSR), a message for PPP-type uses
Phase I: already in published 3.2
Phase II: adding additional models such as TEC (in progress)
Phase III: carrier based clocks (in early development states)
Coordinate Transformation Messages improvements underway
Network RTK Approaches (i.e., Non-Physical Reference, MAC, and FKP)
Currently GPS and GLONASS only
Committee currently deliberating adding other constellations and signals
Navigation Data Frame (NDF) messages under deliberation
Carries raw navigation data frames from various satellites:
GPS, GLONASS, BeiDou, QZSS, and SBAS.

7. Standards Work In Progress (continued)
Network Transport of RTCM via Internet Protocol (Ntrip)
Ntrip Version 2.0, with Amendment 1
Published on June 28, 2011
Widely used in industry carrying not only RTCM data but numerous other data (even beyond proprietary GNSS receiver data)
Supporting TCP/IP, UDP, and SSL
Work In Progress
Sourcing the Station Log Files
Offering suggested source table meta-names to aid in more automation of stream selections.

8. RINEX Working Group RINEX and SC-104 Tighter Relationship (~2 yrs ago)
RINEX and RTCM essentially deal with same ‘observables’
The independent committees now jointly develop solutions
Example: Phase alignment
Ensure RINEX can be created from RTCM 3.x
Joint decision to only further development of 3.x
Example: RINEX 3.02 supports BeiDou; version 2.x does not.
BKG developing open source for RTCM 3 and RINEX converters
teqc equivalent in the plans
RINEX 3.03 current being considered
Several issues with 3.02 raised by community that may require 3.03
Any version beyond 3.02 will likely undergo RTCM-type interoperability testing

9. NMEA Working Group NMEA and SC-104 Tighter Relationship
RTCM SC-104 Standards messages traditionally from Reference Receiver / Network sent to User
Community requesting standardized messages for high precision work carrying end solutions reaching a wider range of other applications, systems and devices
Formed an NMEA Working Group (WG) within SC-104
Will be developing messages that essentially carry solution results to other applications, systems and devices
Will likely be developing messages targeted at Network management side
Receiver Controls: e.g., reset commands, elevation masks, etc.
These will be developed under NMEA-0183, 2000, and the new OneNet
WG Formed Sept 2013, thus no progress yet to report

10. Thank You
Thank You
RTCM SC-104 Participation
Questions