Design and Validation of Tunnel Positioning Scheme Based on BeiDou Pseudo-Satellite System

In order to achieve better tunnel operation and management and meet the practical requirements of tunnel positioning, this paper proposes a tunnel positioning scheme based on the BeiDou Navigation Satellite System (BDS). The scheme adapts the existing BDS receiver hardware platform through adaptive software upgrades, utilizing the BDS pseudolite system inside the tunnel to achieve positioning. Test verifications show that the introduced pseudolite signal inside the tunnel has a stable signal strength, with carrier-to-noise ratio fluctuations not exceeding 1 dB and 2 dB during stationary and mobile conditions respectively, effectively overcoming the effects of the far-end and near-end issues. The positioning errors of the receiver in the tunnel during stationary and mobile conditions are within 0.5 m and 3.4 m respectively, indicating good positioning accuracy that meets the requirements.