Chinese Optics, Volume. 18, Issue 3, 547(2025)
Pseudo-random code selection for inter-satellite laser ranging and data communication in the Taiji program
The Taiji program aims to achieve inter-satellite laser communication and absolute distance measurement using spread spectrum phase modulation technology based on the interferometric laser link. The selection of pseudo-random codes is the initial step in the design and implementation of the ranging and communication system, which requires comprehensive research and comparison of various aspects, including the implementation principles, correlation properties, and ranging error functions associated with different pseudo-random codes. This paper first elucidates the generation principles of m-sequences, Gold sequences, and Weil sequences. Pseudo-random sequences are generated using different hardware structures such as Fibonacci, Galois, and register addressing. The hardware circuits for Gold and Weil sequence generation are implemented on an FPGA development platform. The GPS C/A code is used as the Gold sequence, which facilitates its comparison and analysis with the Weil sequence. An analysis of the resource consumption and complexity of different hardware implementation methods is performed. Then, correlation values and root mean square errors are calculated to compare the pseudorandom noise performance of the Gold and Weil sequences. Finally, an error function for ranging is constructed based on the ranging principles and the intersymbol interference phenomenon after laser interference. This function is then compared with the ideal error function to evaluate the advantages and disadvantages of using different pseudorandom codes for ranging. The analysis reveals that Weil sequences demonstrate superior performance, exhibiting a sidelobe range of -60.27 dB to -24.01 dB, an autocorrelation rms of 0.303, and a cross-correlation rms of 0.307, outperforming Gold sequences in all metrics. Additionally, Weil sequences require only 30% of the hardware resources of Gold sequences and have a smaller error function deviation. Weil sequences are better suited to the laser ranging and data communication requirements of the Taiji program.
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Pei-quan CHEN, Ru-jie DENG, Yi-bin ZHANG, Pan LI, Ke-qi QI, He-shan LIU, Zi-ren LUO. Pseudo-random code selection for inter-satellite laser ranging and data communication in the Taiji program[J]. Chinese Optics, 2025, 18(3): 547
Category: Special Column on Space-based Gravitational Wave Detection
Received: Feb. 6, 2024
Accepted: Apr. 15, 2024
Published Online: Jun. 16, 2025
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