GB/T 47426-2026General specification for BeiDou/GNSS receivers on board high earth orbit satellites (English PDF)

4.4 Components and Raw Materials

4.4.1 Component Selection The selection of receiver components should meet the requirements for high-performance electronic components for application fields as defined in GB/T 37312.1 and GB/T 41041. The selection of prohibited or restricted aerospace components must comply with the requirements specified in the dedicated technical documents.

4.4.2 Raw Material Selection All components of the receiver should be made of materials that meet the material selection standards, with priority given to materials with successful flight experience and that meet satellite life requirements. The materials requested.

4.5 Electromechanical Heating Interface

4.5.1 Mechanical Interface The receiver's mechanical interface requirements are as follows:

a) The receiver's geometry, mass, and structural design should conform to the mechanical interface requirements specified in the dedicated technical documents;

b) The receiver's fundamental frequency should avoid the spacecraft's structural fundamental frequency or comply with the requirements of the dedicated technical documents;

c) The antenna mounting flange or bracket is typically connected to the spacecraft bulkhead;

d) Under the condition that the electrical performance and interface requirements are met, the mechanical performance of the receiver should not change after environmental testing. It exhibits minimal plastic deformation, and is characterized by its simple structure, small size, light weight, and good processability and maintainability.

e) The flatness of the receiver should not exceed

0.1 mm/(100 mm × 100 mm);

f) The surface roughness of the receiver should not exceed 3.2 µm;

g) If the receiver's non-sealed structure forms a sealed cavity, the housing should have one or more vent holes not exceeding phi2mm.

4.5.2 Electrical Interface The receiver's electromechanical interface requirements are as follows:

a) The antenna, low-noise amplifier, and receiver main unit RF interface are connected via a coaxial 50Omega electrical connector;

b) The receiver's 1PPS interface circuit adopts either LVDS signal form or RS422 interface form;

c) The receiver reverse ripple requirements shall meet the specifications outlined in the dedicated technical documentation;

d) The overall overlap resistance is generally less than 10mOmega;

4.6 Functions

4.6.1 Positioning and Speed Measurement The receiver should possess one or more signal processing capabilities under BDS (B1I, B1C, B2a). The receiver should provide real-time single-signal processing under BDCS. The program calculates position and velocity information and outputs filtered position and velocity information based on the orbital dynamics model as required. The output position and velocity... The degree information corresponds to the path time information.

4.6.2 Time synchronization The receiver should have 1PPS output and time information output functions, with the output time in BDT. It can be converted to [other formats] as needed. UTC or GPST.

4.6.3 Multi-constellation compatibility The receiver should have continuous independent positioning and timing functions based on BDS, and be compatible with GPS, Galileo, GLONASS and other systems as needed. The system achieves fusion processing and coordinate transformation as needed.

4.6.4 Fault Tolerance The receiver should have fault-tolerant capabilities, including.

a) Software anomalies such as receiver autonomous monitoring signal tracking anomalies, pseudorange measurement anomalies, message demodulation anomalies, and receiver positioning anomalies. Hardware malfunction, and autonomously recovers from the abnormal state;

b) It has single-event protection and single-event fault recovery capabilities;

c) Perform redundancy processing on critical data;

d) Strengthen the program's hardened storage area and implement load fault tolerance.

4.6.5 Output The receiver should have the function of outputting positioning information, speed measurement information, time synchronization information, and operating status, generally including.

a) Location, velocity, and corresponding time stamp for single-point positioning;

b) Position, velocity, and corresponding time stamps after track filtering;

c) The standard time corresponding to a 1PPS signal;

d) Receiver power supply voltage;

e) Receiver continuous operating time;

4.7.1 Antenna Performance

4.7.1.1 Antenna operating frequency and bandwidth The antenna's operating frequency and bandwidth should ideally cover BDS signals such as B1I, B1C, and B2a; the signal operating frequency bands are detailed in Appendix A. This can be determined based on the specific application. User needs must be met to cover signals from GPS, Galileo, GLONASS, and other systems. The frequency coverage requirements and specific bandwidths for each frequency point should meet [the requirements]. Specific technical documentation requirements.

4.7.1.2 Antenna Gain Depending on the orbital altitude, the antenna gain characteristics should meet the values given in Table 1. The simulation results of the antenna gain under satellite mounting conditions and the individual antenna test results should both meet the requirements.

4.7.1.3 Antenna Voltage Standing Wave Ratio Within each receiving frequency range, the antenna voltage standing wave ratio should not exceed 1.5.

4.7.2 Low-noise amplifier performance The low-noise amplifier should ideally cover the BDS signals B1I, B1C, and B2a, and can also cover GPS signals according to user needs. Signals from systems such as Galileo and GLONASS. The gain of the low-noise amplifier should not be less than 30dB, the noise figure should not be greater than 2.0dB, and the voltage standing wave ratio should be less than 1.5. The out-of-band signal suppression of the low-noise amplifier should meet the user's specific requirements.

4.7.3 Precision Accuracy encompasses five aspects. time synchronization accuracy, positioning accuracy, speed measurement accuracy, filtered positioning accuracy, and filtered speed measurement accuracy. (Accuracy technology) The characteristics should meet the characteristic values given in Table 2. The timing accuracy is the standard deviation (STD) of the deviation between the output 1PPS signal and the standard time signal. Positioning accuracy, speed measurement accuracy, and filtered positioning are also included. Accuracy and filtered speed measurement accuracy are the three-dimensional root mean square error (RMS) of the deviation from the reference value.

4.7.4 Signal Reception Performance

4.7.4.1 Signal Tracking Channel Each signal in the receiver should ideally have 12 channels.

4.7.4.2 Signal Acquisition Sensitivity The receiver signal acquisition sensitivity is based on the low-noise amplifier aperture signal acquisition using a right-hand circularly polarized antenna and a gain of 0 dBi. The sensitivity minus the antenna gain should ideally meet the characteristic values given in Table 3.

4.7.4.3 Signal Tracking Sensitivity Receiver signal tracking sensitivity is achieved using a right-hand circularly polarized antenna with a gain of 0 dBi for low-noise amplifier aperture signal tracking. The sensitivity minus the antenna gain should ideally satisfy the characteristic values given in Table 4.

4.8 Environmental adaptability

4.8.1 Temperature The receiver's operating temperature range should meet the following requirements.

a) The operating temperature range of low-noise amplifiers and receivers is generally -15°C to 50°C;

b) When the orbital altitude is less than 30,000 km, the antenna operating temperature range is generally -150°C to 112°C; when the orbital altitude is 30,000 km... At 400,000 km, the antenna's operating temperature should comply with the specifications in the dedicated technical documents.

4.9 Mature Refining The receiver shall undergo aging tests in accordance with the requirements specified in GB/T 42863-2023 or the provisions of the dedicated technical documents. After the test... The receiver's functionality and performance meet the requirements.

4.10 Reliability The receiver reliability requirements are as follows:

a) It should have quantitative reliability indicators and verification analysis;

b) Single-event lockout prevention measures should be implemented during the design phase, and redundant design should be adopted;

c) Single points of failure should be avoided in the design; for single points of failure that are technically difficult to eliminate, their failure rate should be reduced through design.

d) The lifespan should not be less than the design lifespan of the satellite platform. At the end of the design lifespan, the receiver reliability should preferably not be less than 0.8.

4.11 Security The security protection requirements for the receiver are as follows:

a) Each interface should be clearly marked and have measures to prevent incorrect insertion;

b) During the inspection, soldering, and various tests of integrated circuits, specific process documents should be followed to avoid electrostatic damage;

c) It should have overcurrent, overvoltage, and transient power supply protection capabilities, and should ensure that a fault in the equipment itself will not damage other equipment on the satellite. The normal operation of its own equipment may be affected by the failure of other equipment on the satellite.

4.12 Electromagnetic Compatibility The receiver should be configured according to the satellite mission requirements and in accordance with the EMC requirements for subsystems and equipment described in Chapter 7 of GB/T 40134-2021. The specialized documentation is designed to meet the mission-specified requirements for conducted emission, conducted sensitivity, radiated emission, and radiated sensitivity.

5.7 Inspection of electromechanical heating interfaces

5.7.1 Mechanical Interface Use visual inspection, vernier calipers, and plug gauges for inspection.

5.7.2 Electrical Interface Perform an electrical interface check on the receiver.

a) Visually inspect the electrical interface type and use a multimeter to measure the resistance;

b) Use a milliohmmeter to test the connector ground resistance;

c) Test the connection of the high-frequency connector to check if its threads are intact;

d) The receiver should operate normally within the voltage range specified in the dedicated technical documents;

e) Use current clamps and an oscilloscope to check for surges.

5.7.3 Hot Interface Check the product's thermal control coating test report and thermal test report.

5.7.4 Other Interfaces Check other interfaces according to the requirements of the specific technical documents.

5.8 Functional Testing

5.8.1 Test Instructions The receiver unit, in conjunction with the low-noise amplifier, completed the functional tests in section

4.6 and the performance tests in sections

4.7.3 and 4.7.4.The low-noise amplifier completed the tests independently. Performance testing

4.7.2 is performed.

5.8.2 Positioning and Speed Measurement Functions The testing environment for the positioning and speed measurement functions is shown in Figure 1. Figure

1.Schematic diagram of receiver positioning, speed measurement and time synchronization function test connection. The testing steps for the positioning and speed measurement functions are as follows:

a) Connect the testing instrument and the device under test as shown in Figure 1;

b) Use a GNSS satellite signal simulator for effective testing. Set up the simulator in a high-orbit dynamic scenario and configure it according to requirements. It can be a single system or multiple systems, and it runs a signal simulator;

c) Power on the receiver. Once the receiver's status indicator displays "Positioning data is valid," observe the receiver's performance on various systems using the test computer. Can it output the correct position and velocity information?

5.8.3 Time synchronization function The test environment for the time synchronization function is shown in Figure 1. The timing function test steps are as follows:

a) Connect the test instrument and the device under test as shown in Figure 1.

b) Use a GNSS satellite signal simulator for effective testing. Set up the simulator in a high-orbit dynamic scenario and configure it according to requirements. It can be a single system or multiple systems, and it runs a signal simulator.

c) Power on the receiver. After the receiver's operating status display shows a valid time output, observe whether it can output correctly in each operating mode. BDS time and outputs UTC or GPS time according to instructions.

d) After the receiver's working status display shows a valid time output, observe the GNSS signal sampled by the time interval analyzer shown in Figure 1. The time difference (1s ambiguity) between the analog 1PPS signal and the receiver 1PPS signal. The 1PPS output function includes 1PPS offset. The error is divided into two parts. deviation and random error, with 1PPS deviation recorded as the zero value of the equipment. When the equipment connection relationship changes, it needs to be re-established. Measure or modify according to changes in cable length.

6.5 Judgment Rules

6.5.1 Criteria for Passing Inspection and Testing If all mandatory inspection items meet the requirements, the inspection is deemed (qualified). If any non-compliance exists, one re-inspection is permitted. If it still fails to pass, the product is deemed unqualified.

6.5.2 Criteria for Acceptance Inspection If all mandatory inspection items for delivery and acceptance meet the requirements, the delivery and acceptance inspection is deemed (qualified). If any non-conformity exists, one re-inspection is permitted. If it still fails to pass, the product is deemed unqualified.

6.5.3 Re-inspection Rules For products with non-conformities, the following rules shall apply.

a) For products with non-conformities, the following rules shall apply. Before environmental testing, the manufacturer shall... Investigate and repair the fault, and write a written report. Retest and re-inspect after repair.

b) In the event of an environmental test failure, the product shall be retested and re-measured in accordance with the provisions of section

4.8 of GB/T 42863-2023. Inspect and write a written report.