To meet the urgent need for high-precision ranging and large-capacity transmission in the current BeiDou-3 inter-satellite link system, this paper proposes a novel two-way measurement method based on Co-frequency Co-time Full Duplex (CCFD) system. This approach effectively addresses the limitations of traditional Time-Division Half-Duplex (TDHD) systems, such as complex link establishment processes, constrained ranging accuracy, and limited transmission efficiency. Based on the spatial configuration of the BeiDou-3 satellite navigation constellation, a dynamic link constraint model is constructed, and a comprehensive link budget analysis is conducted for the entire inter-satellite measurement process. The fundamental principle, system model, and key errors of the two-way measurement in CCFD are derived in detail. Theoretical analysis and experimental simulations demonstrate that the proposed CCFD system is feasible and achieves remarkable ranging accuracy improvements. At a carrier-to-noise ratio of 61.6 dBHz, the system attains 1σ ranging accuracy of 1.9 cm, representing a 51.3% enhancement over the 3.9 cm accuracy of the TDHD system. When operating at 69.3 dBHz, the precision further improves to 0.8 cm, outperforming TDHD’s 2.2 cm by 66.8%. The introduction of CCFD technology can significantly enhance the performance level of the BeiDou-3 satellite navigation system, demonstrating broad application prospects for the future.

During the demodulation process of spread-spectrum telemetry signals, the computational load of acquisition operations is extremely large. Without the assistance of hardware peripherals, traditional CPU-based software demodulation devices struggle to achieve real-time acquisition and processing of spread-spectrum signals. This paper proposes a parallel architecture based on CPU + GPU to accelerate the PMF - FFT acquisition algorithm. By means of block compensation, the influence of pseudo-code Doppler on the despreading operation is eliminated. The overall process of the parallel PMF - FFT algorithm and the corresponding computational kernels for each step are designed and the algorithm verified through experiments. The experiments show that for spread-spectrum telemetry data with a sampling rate of 56 MHz, this algorithm can achieve real-time acquisition of spread-spectrum signals. It has an acceleration ratio of approximately 24 times compared with the serial computing method. It can effectively acquire spread-spectrum signals with different signal parameters and meet the corresponding signal-to-noise ratio requirements. The relevant parameters of the algorithm can be flexibly adjusted according to the parameters of the processed signals. Compared with hardware peripherals such as DSP and FPGA, it shows good scalability, which conforms to the development trend of software-based measurement and control.