KEYWORDS: Laser communications, Laser communication terminals, Acquisition tracking and pointing, Data transmission, Control systems, Satellite communications
Space laser communication has the advantages of fast transmission rate, strong anti-interference ability and high confidentiality, and is the future development trend of high-speed data transmission in space. The laser beam dispersion angle is small, and the field of view of space environment reception is limited, so it is necessary to track the beam stably in order to realize high-speed data communication. However, due to the influence of certain environmental factors or internal factors of the terminal, the tracking process will inevitably break the chain, which can not ensure stable data communication. Acquisition and tracking is a fast servo control system. It is difficult to diagnose the cause of chain breakage by viewing the telemetry on the bus to capture the state at the moment of chain breakage after the chain is built by on-rail laser communication. Aiming at this problem, this paper proposes a diagnostic method of broken chain for space laser communication, so that the relevant data can be locked at the moment of broken chain after the satellite enters the orbit and the data can be transmitted back to the ground. Then the professionals can analyze the cause of the broken chain and find the corresponding solutions to modify it in the orbit.
This paper introduces a design and implementation of high frequency signal acquisition and control system based on DSP + FPGA. The system supports internal/external clock and internal/external trigger sampling. It has a maximum sampling rate of 400MBPS and has a 1.4GHz input bandwidth for the ADC. Data can be collected continuously or periodically in systems and they are stored in DDR2. At the same time, the system also supports real-time acquisition, the collected data after digital frequency conversion and Cascaded Integrator-Comb (CIC) filtering, which then be sent to the CPCI bus through the high-speed DSP, can be assigned to the fiber board for subsequent processing. The system integrates signal acquisition and pre-processing functions, which uses high-speed A/D, high-speed DSP and FPGA mixed technology and has a wide range of uses in data acquisition and recording. In the signal processing, the system can be seamlessly connected to the dedicated processor board. The system has the advantages of multi-selectivity, good scalability and so on, which satisfies the different requirements of different signals in different projects.
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