GB/T 45950-2025 in English

Standard Overview and Technical Background

GB/T 45950-2025 "Fengyun-4 Meteorological Satellite Direct Broadcast High-Speed Information Transmission Protocol" is my country's first national standard formulated for high-speed data broadcasting of geostationary meteorological satellites. The standard was released in 2025, marking that my country's meteorological satellite data broadcasting technology has entered the stage of standardization and normalization.

In-depth Analysis of Protocol Architecture

The standard adopts a layered protocol architecture, dividing the data transmission process into 7 relatively independent and interrelated layers:

Technical Characteristics of Core Instrument Payload

Multi-Channel Scanning Imaging Radiometer (AGRI)

As the primary payload of the FY-4 satellite, AGRI adopts an off-axis three-mirror main optical system with 14 observation channels, capable of achieving regional observations in as fast as one minute. Its technological level is nearly three times higher than that of the Fengyun-2 satellite, achieving for the first time the ability to generate color satellite cloud images. The GIIRS is the world's first geostationary infrared hyperspectral interferometry instrument. It utilizes a 32×4 array detector and uses Michelson interferometry to detect vertical distributions of atmospheric temperature and humidity, marking my country's transition from two-dimensional observations to three-dimensional integrated observations. The GHI offers high-resolution imaging capabilities covering an area of 2000 km×2000 km with a temporal resolution of less than one minute, providing excellent monitoring capabilities for rapidly evolving weather systems such as typhoons and severe convection. The LMI is the first geostationary lightning imager developed in the Asia-Pacific region. It utilizes a CCD array and optical imaging technology to observe all types of lightning, including cloud-to-cloud, cloud-to-ground, and cloud-to-ground flashes.

Data Transmission Security Mechanism

The standard adopts a two-layer encryption system to ensure data security:

Each authorized user station obtains a private key through manual application and obtains the public key file through HRIT broadcast, achieving end-to-end secure data transmission.

Virtual Channel Allocation Strategy

The standard defines five virtual channels corresponding to physical links:

Implementation Recommendations and Compliance Requirements

Receiving Station Construction Requirements

Newly built FY-4 satellite data receiving stations should ensure: L-band reception frequency coverage of 1670-1702MHz; QPSK demodulation capability; support for MPEG-2 data encapsulation and parsing; and compliance with DVB-S2 standard requirements.

Data Processing Specifications

The data receiving end should strictly parse the data format specified in Appendix B, especially correctly interpreting key data structures such as the HRIT main file header and imager data information header.

Security and Compliance Management

User stations must apply for authorization to receive data through formal channels, properly keep private keys, regularly update key files, and establish a comprehensive data security management system.

Technology Evolution and Development Trends

GB/T 45950-2025 was developed based on the standards of the Consultative Committee for Space Data Systems (CCSDS) and incorporates the practical experience of my country's Fengyun satellite projects. With the development of satellite technology in the future, this standard will continue to evolve to support higher transmission rates, stronger encryption capabilities, and more intelligent data scheduling mechanisms.

The implementation of this standard will significantly improve the broadcast efficiency and service capabilities of my country's meteorological satellite data, providing reliable technical support for application areas such as weather forecasting, climate monitoring, and disaster warning.