Design and implementation of a high-sensitivity receiver channel for the BeiDou RDSS

With the growing adoption of BeiDou RDSS short-message applications, increasingly stringent requirements are imposed on the reception sensitivity and long-term operational stability of user terminals. To meet these demands, we introduce an RDSS-oriented receiver design that enhances overall sensitivity by jointly optimizing a two-stage cascaded low-noise amplifier (LNA) front end, a superheterodyne down-conversion chain, and noncoherent signal acquisition in the presence of frequency offsets. In addition, we develop a cost-efficient local oscillator (LO) aging compensation approach that integrates an improved resistor divider tuning network with embedded software algorithms to mitigate frequency drift caused by crystal aging and maintain reliable reception of weak signals over multiple years. Experimental validation shows that the solution delivers a total gain of 28.19 dB and a noise figure (NF) of 1.87 dB. The receiver satisfies the sensitivity requirement of a bit error rate (BER) [Formula: see text] at -127.6 dBm and maintains near-threshold demodulation performance at -128.1 dBm, demonstrating competitive high-sensitivity weak-signal reception capability relative to the commonly reported benchmark. The proposed LO aging-compensation model provides a discrete tuning step size of 1016.6 Hz, enabling a 32-point search-and-lock procedure that compensates aging-induced drift and prevents frequency-offset-driven degradation in weak-signal acquisition and demodulation. Furthermore, the constructed end-to-end testing platform transmitted 10,380 messages with a 99.31% success rate, surpassing the required threshold of 95% by 4.31 percentage points. This further validates the reliability and engineering applicability of the solution under real-world conditions. Overall, the experimental findings confirm that the proposed high-sensitivity receiver system delivers reliable weak-signal reception performance and practical engineering value, supporting the further deployment of BeiDou RDSS short-message services.