GB/T 45950-2025Transmission protocol for FY-4 direct broadcast high rate information (English PDF)

风云四号气象卫星直接广播高速信息传输协议

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Issued by

SAMR; SAC

Level / Type

National · Recommended

Issue date

August 1, 2025

Implementation date

November 1, 2025

Scope

GB/T 45950-2025 is the English-translated version of 风云四号气象卫星直接广播高速信息传输协议.

GB/T 45950-2025 is the Chinese national standard covering receiving the direct broadcast from a Fengyun-4 weather satellite — the protocol stack from the physical layer, which follows the DVB satellite standard, up through the data link, network, transport, session and presentation layers to the application, the HRIT file headers, the imager positioning and calibration records, the virtual channel numbering, and the key records that let one ground station decrypt what it is entitled to receive. First edition, under the China Meteorological Administration. In force from 1 November 2025. Issued on 1 August 2025, it has been in force since 1 November 2025.

Document preview — GB/T 45950-2025

National Standard of the People's Republic of China

ICS: 07.060
Classification: A 47

Issued by: State Administration for Market Regulation; Standardization Administration of the PRC

PrefaceIII
1 Scope1
2 Normative references1
3 Terms and Definitions1
4 Abbreviations2
5 Transport Protocol2
5.1 Protocol Structure2
5.2 Application Layer3
5.3 Presentation Layer3
5.4 Session Layer3
5.5 Transport Layer4
5.6 Network Layer4
5.7 Data Link Layer5
5.8 Physical Layer6
Appendix A (Informative) Introduction to the Main Instruments of the Fengyun-4 Optical Meteorological Satellite7
A.1 Multi-channel Scanning Imaging Radiometer (AGRI)7
A.2 Interferometric Atmospheric Vertical Sounder (GIIRS)7
A.3 Rapid Imager (GHI)7
A.4 Lightning Imager (LMI)7
A.5 AGRIL1 Data7
A.6 AGRIL2 Data8
A.7 GIIRSL1 Data8
A.8 GHIL1 Data8
A.9 LMIL2 Data8
A.10 Service Information Data8
Appendix B (Normative) Fengyun-4 Meteorological Satellite High-Speed Information Transmission Data Format9
B.1 HRIT main file header format9
B.2 File Header Type Definition9
B.3 Broadcast Data File Type Definition9
B.4 Imager data information header record format10
B.5 Imager data positioning information recording format10
B.6 Imager data calibration information recording format11
B.7 Annotation Record Format11
B.8 Timestamp Record Format11
B.9 Additional Text Information Header Record Format11
B.10 Key Information Header Record Format12
B.11 Additional Key File Secondary Header Record Format12
B.12 Single User Station Key Group Data Structure12
B.13 Virtual Channel Number VCID Definition12
Reference14

Foreword

This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for standardization work Part 1: Structure and drafting rules for standardization documents" Drafting.

Some of the contents of this document may involve patents. The issuing organization of this document does not assume the responsibility for identifying patents.

This document was proposed by the China Meteorological Administration.

This document is under the jurisdiction of the National Technical Committee for Satellite Meteorology and Space Weather Standardization (SAC/TC347).

This document was drafted by: National Satellite Meteorological Center (National Space Weather Monitoring and Early Warning Center), China Meteorological Administration Meteorological Cadre Training Institute Institute, Beijing Huayun Xingditong Technology Co., Ltd., and Unit 61741 of the People's Liberation Army of China.

The main drafters of this document are: Gao Yun, Ji Cuiling, Liang Yonglou, Guo Xuexing, Sha Jin, and Li Honglin.

Fengyun-4 meteorological satellite directly broadcasts high-speed information Transport Protocol

1 Scope

This document specifies the high-speed information transmission protocol used by the Fengyun-4 meteorological satellite data during direct broadcast, including the application layer, presentation layer, The content and format of the data layer, session layer, transport layer, network layer, data link layer, and physical layer.

This document applies to the sending and receiving of high-speed information in direct broadcast of Fengyun-4 meteorological satellite.

2 Normative references

IEC 10918

IEC 18033

3 Terms and Definitions

The following terms and definitions apply to this document.

3.1 Directed broadcast

Information data is sent from the ground to the satellite, and then directly radiated downward from high altitude to the coverage area through the communication transponder carried by the satellite.

The process of receiving terminals within the area.

3.2 High-speed information transmission

A method of transmitting information using a higher-speed channel.

Note. The general rate is 0.256Mbit/s~10Mbit/s.

[Source. GB/T 39094-2020, 5.1.8]

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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 15 pages — is available in the English PDF.

Referenced standards

Normative references

IEC 10918 · IEC 18033

Editions of GB/T 45950

Edition	Title	Revision	Status
GB/T 45950-2025	Transmission protocol for FY-4 direct broadcast high rate information	current edition	Current

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