1. for Maritime Services)
RTCM Data Format
(Radio Technical Commission
for Maritime Services)

2. Overview of Common GPS Data Format
RINEX
Raw GPS static data format for data processing and archive
NMEA
Standard related to data communication between marine electronic devices.
Transmission of GPS position from GPS receiver to other devices (e.g. GPS receiver to PDA)
For real time positioning
RTCM SC-104
Transmission of GPS correction from GPS reference station to GPS Rover
For DGPS/RTK surveys

3. Outline Example of using RTCM Data Format About RTCM
RTCM Data Structure
RTCM Message Types

4. RTCM using in SatRef
SatRef System
DGPS
Single-RTK
Network-RTK
All GPS corrections from SatRef are in RTCM-2.1 data format.

5. About RTCM

6. Radio Technical Commission for Maritime Services
Various Special Committees set the standards for International maritime radionavigation and radiocommunication
Examples:
GPS Applications
Electronic Charts…..

7. What is RTCM SC-104 ?
RTCM Special Committee (SC) 104 is the one concerned GPS correction signal.
RTCM data format related to GPS corrections is called RTCM SC-104 data format.
Compact binary data
good for real-time processing

8. What is RTCM SC-104 ? Different versions
RTCM-2.0 (Code correction ->DGPS)
RTCM-2.1 (Code + Phase correction -> RTK)
RTCM 2.2 ( …+ GLONASS )
RTCM 2.3 ( ….+ GPS Antenna Definition)
RTCM 3.0 (….+ Network RTK & GNSS)

9. RTCM Data Structure
(Versions )

10. RTCM Data Structure
Each data record contains several message types for various contents.
Message 1, Message2…. Message N
Each message comprises header and body
Header: message type, time, length of message,
Body: data for every data type

11. RTCM Message Types (Versions 2.0-2.3)

12. RTCM Message Types RTCM Message Type Description 1
Differential GPS Corrections 2
Delta Differential GPS Corrections 3
GPS Reference Station Parameters 4
Reference Station Datum 5
GPS Constellation Health 6
GPS Null Name 7
DGPS Beacon Almanac 8
Pseudolite Almanac 9
GPS Partial Correction Set 10
P-Code Differential Correction 11
C/A Code, L1, L2 Delta Corrections 12
Pseudolite Station Parameter 13
Ground Transmitter Parameter 14
GPS Time of Week 15
Ionospheric Delay Message

13. RTCM Message Types 18-21 messages added in RTCM2.1 23-24 messages16
GPS Special Message 17
GPS Ephemerides 18
RTK Uncorrected Carrier Phases 19
RTK Uncorrected Pseudorange 20
RTK Carrier Phase Corrections 21
RTK Pseudorange Corrections 22
Extended Reference Station Parameters 23
Antenna Type Defination 24
Reference Station: Antenna Reference Point (ARP) Parameter
25, 26
Undefined 27
Extended DGPS Radiobeacon Almanac
28…30 31
Differential GLONASS Corrections 32
Differential GLONASS Reference Station 33
GLONASS Constellation Health 34
GLONASS Partial Differential Correction Set
GLONASS Null Name (N<=1)
18-21 messages
added in RTCM2.1
23-24 messages
added in RTCM2.3
31-36 messages
added in RTCM2.2

14. RTCM Message Types 31-36 messages added in RTCM2.2 35
GLONASS Radiobeacon Almanac 36
GLONASS Special Message 37
GNSS System Time Offset
38..58
Undefined 59
Proprietary Message
60..63
Multipurpose Usage

15. RTCM Raw Data
Binary data

16. RTCM Message Type 1
1. Pseudorange Corr.
2. Range Rate Corr.

17. RTCM Message Type 3+22

18. RTCM Message Type 20

19. RTCM Message Type 21

20. RTCM version 3.0

21. RTCM version 3.0
RTCM 3.0
New data structure developed for network RTK applications.
new signals L2C and L5
GNSS system data
Compact Data Structure
RTCM 2.0 – 0.5 kbit / sec. (DGPS)
RTCM requires 5 kbit / sec (DGPS+RTK)
RTCM 3.0.requires 2 kbit / sec

22. Four Groups of RTCM 3.0 GNSS RTK messages (RTCM 2004)
Group Name
Message Type
Message Description
Observations
1001
L1-only GPS RTK Observables
1002
Extended L1-Only GPS RTK Observables
1003
L1 & L2 GPS RTK Observables
1004
Extended L1 & L2 GPS RTK Observables
1005
L1 Only GLONASS RTK Observables
1006
ExtendedL1-Only GLONASS RTK Observables
1007
L1 & L2 GLONASS RTK Observables
1008
Station Coordinates
1009
Stationary RTK Reference Station ARP
1010
Stationary RTK Reference ARP with Antenna Height
Antenna Description
1011
Antenna Descriptor
1012
Antenna Descriptor & Serial Number
Auxiliary Operation Information
1013
System Parameters

23. References
RTCM Recommended Standards for Differential NAVSTAR GPS service
RTCM Official Website
DGPS Data Formats 2.0
Reference Station Network Information Distribution

24. The End Thank you!