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GB/T 47425-2026Performance requirements and test methods for the navigation module of the SAR/BDS return link service (English PDF)

北斗国际搜救返向链路导航模块性能要求及测试方法

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Issued by

SAMR; SAC

Level / Type

National · Recommended

Issue date

April 30, 2026

Implementation date

August 1, 2026

Scope

GB/T 47425-2026 is the English-translated version of 北斗国际搜救返向链路导航模块性能要求及测试方法.

GB/T 47425-2026 is the Chinese national standard covering the navigation module inside a distress beacon - it has to fix its own position accurately enough to send with the alert, from a beacon that may be in the water, under a canopy or damaged. First edition, in force since 1 August 2026, with the SAR/BDS interface standard GB/T 47423-2026. It was issued on 30 April 2026 and has been in force since 1 August 2026, as a first edition. This page is published from the official record of the 2026 edition; the clause text of a standard this recent is not yet in circulation, and the figures, limits and tables it contains are those of the document itself, delivered in full with the English translation.

Document preview — GB/T 47425-2026

National Standard of the People's Republic of China

ICS: 33.060.20
Classification: M 35

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

4 Technical Requirements
4.2 Functional Requirements
4.3.1 Satellite navigation signal reception and processing
4.3.2 Return Link Spatial Signal Reception and Processing
4.4 Interface Requirements
4.5 Environmental adaptability requirements
5 Test Methods
5.4 Functional Check
5.5 Performance Testing
5.5.1 Satellite navigation signal reception and processing
5.5.2 Return Link Spatial Signal Reception and Processing
5.6 Interface Testing
5.6.2 Navigation Information Statements Perform the test according to
5.6.3 BeiDou RLM Output Statements Perform the test according to
5.7 Environmental adaptability test

Foreword

This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part

1.Structure and Drafting Rules of Standardization Documents". Drafting. Please note that some content in this document may involve patents. The issuing organization of this document assumes no responsibility for identifying patents. This document was proposed by the Equipment Development Department of the Central Military Commission. This document is under the jurisdiction of the National BeiDou Satellite Navigation Standardization Technical Committee (SAC/TC544). This document was drafted by: China Satellite Navigation Engineering Center, China Electronics Technology Group Corporation (Ningbo) Marine Electronics Research Institute Co., Ltd., and China Transport Telecommunications. Information Center, the 20th Research Institute of China Electronics Technology Group Corporation, and Beijing Oriental Measurement and Testing Institute. The main drafters of this document are. Li Gang, He Zehua, Yang Xiaoheng, Yang Congxi, Liu Lijiao, Guo Shuren, Yang Wenhui, Gao Weiguang, Lu Yun, and Su Chenggeng. Lu Hongyang, Gao Ya, Xu Lili, Wang Tian, Chen Ying, Chen Liang, Chen Zhengkun. Beidou International Search and Rescue Return Link Navigation Module Performance Requirements and Test Methods

1.Scope This document specifies the technical requirements for the composition, function, performance, and interfaces of the BeiDou international search and rescue return link navigation module, and describes the corresponding... Test method. This document applies to the design, development, production, and testing of the BeiDou international search and rescue return link navigation module.

4 Technical Requirements

4.1 Composition This module is generally used to support the 406MHz beacon in the BeiDou return link. The module mainly consists of an RF signal processing unit and a baseband processing unit. It consists of functional units such as the Beidou satellite navigation information processing unit, the Beidou RLM processing unit, and the data output interface unit, and can be externally connected to... The active or passive antenna operates, and the module composition is shown in Figure 1.

4.2 Functional Requirements

4.2.1 Positioning The module should support the reception and positioning calculation of BeiDou satellite navigation signals and have the ability to output positioning results.

4.2.2 RLM Reception and Output The module should support the reception of BeiDou satellite navigation B2b signals and comply with Chapter 6 of GB/T 39414.5 and GB/T 47423-2026. The requirement is to parse, process, and output the RLM messages in the B2b signals of BeiDou MEO and IGSO satellites.

4.3.1 Satellite navigation signal reception and processing

4.3.1.1 Capture Sensitivity The acquisition sensitivity level should not exceed -133 dBm. The acquisition sensitivity of other satellite navigation signals should comply with relevant standards or technologies. Standard requirements.

4.3.1.2 Tracking Sensitivity The tracking sensitivity level should not exceed -133 dBm. The tracking sensitivity of other satellite navigation signals should comply with relevant standards or technologies. Standard requirements.

4.3.1.3 Positioning Accuracy The positioning accuracy should be better than 10m. The positioning accuracy of other satellite navigation signals should meet the requirements of relevant standards or technical specifications.

4.3.1.4 Cold start positioning time The cold start positioning time should not exceed 60 seconds.

4.3.1.5 Loss-of-lock recapture time The recapture time after loss of lock should not exceed 5 seconds.

4.3.2 Return Link Spatial Signal Reception and Processing

4.3.2.1 B2b signal receiving sensitivity Without considering antenna gain and with a bit error rate not exceeding 1e-5, the B2b signal receiving sensitivity level should not exceed -135dBm.

4.3.2.2 Number of B2b signal tracking channels The module should have at least 12 channels capable of simultaneously tracking B2b signals from both BeiDou MEO and IGSO satellites.

4.3.2.3 BeiDou RLM Output Statement Response Time After receiving the BeiDou RLM message, the module should output an RLM statement that meets the requirements of 4.4.3, and the response time should not exceed 2 seconds.

4.4 Interface Requirements

4.4.1 General Requirements The module should provide at least the following interfaces.

a) Radio frequency interface, supporting the connection of active or passive antennas;

b) Data interface. The module shall provide at least one output interface compliant with IEC 61162-1.2024 requirements, supporting asynchronous serial communication. Output statements for navigation information and return link messages;

c) Power interface, compatible with 3.3V~5V power supply voltage.

4.4.2 Navigation Information Statements The navigation information output by the module should include at least GPS Fixed Data (GGA) language conforming to Chapter 7 of IEC 61162-1.2024. One of the following. GNSS Fixed Data (GNS) statement, or Recommended Minimal Specific GNSS Data (RMC) statement.

4.4.3 BeiDou RLM Output Statements The BeiDou RLM output statement from the module should include the beacon ID, reception time, message type, and message content. Among these, the beacon ID and message type... The data type and message content are received from the satellite. The format of the output statement and the field definitions and descriptions are shown in Figure 2 and Table 1, respectively.

4.5 Environmental adaptability requirements

4.5.1 Operating Temperature The module should be able to operate normally in an ambient temperature range of -20°C to 55°C.

4.5.2 Vibration The module should be able to withstand wideband random vibrations in the frequency range of 20Hz to.2000Hz.

5 Test Methods

5.1 Test Environment Unless otherwise specified, all test environment conditions shall meet the following requirements.

a) Temperature. 15°C~35°C;

b) Relative humidity. 20%~80%. If the actual test conditions cannot meet the above environmental conditions, the test results should indicate the actual ambient temperature and relative humidity during the test.

5.2 Testing Instruments and Equipment The test was conducted using a GNSS signal simulator. The test equipment met the following requirements.

a) It should have been verified or calibrated by a metrology department, and the parameters or range should meet the performance requirements and be within the validity period of the verification or calibration;

b) The simulated test signal generated by the GNSS signal simulator should have the same characteristics as the satellite signal and be able to function under normal dynamic constellation conditions. Generate satellites with good geometric positioning (planar accuracy attenuation factor less than or equal to 4, or point accuracy attenuation factor greater than or equal to 6). star signal;

c) The GNSS signal simulator supports the broadcasting of BeiDou B2b signals and RLM signals;

d) The performance of the GNSS signal simulator, including measurement range, resolution, accuracy, and stability, shall comply with GB/T 39413. Regulation.

5.3 Test Items The test items, corresponding technical requirements, and test methods are shown in Table 2.

5.4 Functional Check

5.4.1 Positioning According to the instruction manual provided by the manufacturer of the module under test, the GNSS signal simulator broadcasts the satellite navigation signals supported by the module under test to check for accuracy. Check if there is a location result output.

5.4.2 RLM Reception and Output According to the instruction manual provided by the manufacturer of the module under test, the output interface of the module under test is connected to a computer, and a GNSS signal simulator generates and... Broadcast B2b signals conforming to Chapter 6 of GB/T 47423-2026, and the equivalent signal strength at the RF input of the module under test. The value is -135dBmW. The information output by the module under test is checked and confirmed by using the manufacturer's software or third-party software to read the information. The information output by the module is consistent with the information sent by the GNSS signal simulator.

5.5.1 Satellite navigation signal reception and processing

5.5.1.1 Capture Sensitivity The test shall be conducted according to the method specified in

6.4.1.2 of GB/T 42576-2023.

5.5.1.2 Tracking Sensitivity The test shall be conducted according to the method specified in

6.4.1.3 of GB/T 42576-2023.

5.5.1.3 Positioning Accuracy The test shall be conducted according to the method specified in 6.4.2.2.1 of GB/T 42576-2023.

5.5.1.4 Cold start positioning time The test shall be conducted according to the method specified in

6.4.3.1 of GB/T 42576-2023.

5.5.1.5 Loss-of-lock recapture time The test shall be conducted according to the method specified in

6.4.4 of GB/T 42576-2023.

5.5.2 Return Link Spatial Signal Reception and Processing

5.5.2.1 B2b signal receiving sensitivity Set up the GNSS signal simulator to a level 2 dB lower than the acquisition sensitivity value stated in the instruction manual provided by the module under test manufacturer. The value starts by generating a B2b signal carrying RLM and transmitting it to the module under test via a feeder, increasing in 1dB steps. If the module under test can... If the corresponding information is output in a timely manner and the bit error rate is not less than 1e-5, then record the level value to confirm whether the B2b signal receiving sensitivity of the module under test meets the requirements. Meets the requirements.

5.5.2.2 Number of B2b signal tracking channels Using a GNSS signal simulator, different content was simultaneously generated and broadcast on 12 satellite channels, conforming to GB/T 47423-2026. Use the RLM message required in Chapter 6 to check whether the output of the module under test meets the requirements.

5.5.2.3 BeiDou RLM Output Statement Response Time In test 5.4.2, the time when the GNSS signal simulator broadcasts the B2b signal and the output of the BeiDou RLM from the module under test are recorded. Check the timing of the statements to confirm whether the time difference between the two meets the requirements.

5.6 Interface Testing

5.6.1 General Requirements Observe the module under test and check the instruction manual provided by the manufacturer to confirm whether the interface of the module under test meets the requirements.

5.6.2 Navigation Information Statements Perform the test according to

5.4.1 to confirm whether the navigation information statements output by the module under test meet the requirements.

5.6.3 BeiDou RLM Output Statements Perform the test according to

5.4.2 to confirm whether the BeiDou RLM output statement of the module under test meets the requirements.

5.7 Environmental adaptability test

5.7.1 Operating Temperature The module operating temperature test is divided into low temperature operating test and high temperature operating test, and the specific methods are as follows:

a) Conduct the test at -20°C according to the method specified in GB/T 2423.1.During the latter part of the temperature stabilization period... GB/T 42576-2023, section 6.4.2.2.1, requires testing the positioning accuracy of the module under test (DUT) to confirm its positioning accuracy. Does the degree meet the requirements?

b) Conduct the test at 55 °C according to the method specified in GB/T 2423.2.During the latter part of the temperature stabilization period, follow the... GB/T 42576-2023, section 6.4.2.2.1, requires testing the positioning accuracy of the module under test and confirming its positioning accuracy. Does it meet the requirements?

5.7.2 Vibration The test was conducted according to the requirements of GB/T 2423.10.The packaged and operational module under test was installed on the vibration test bench. After the test is completed under wideband random vibration conditions in the frequency range of 20Hz to.2000Hz, check and confirm according to the requirements of 5.4.

......
This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 24 pages — is available in the English PDF.

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