The BeiDou Navigation Satellite System with global coverage (BDS-3) was officially launched on July 31, 2020. In addition to the legacy B1I and B3I signals from the regional system (BDS-2), BDS-3 provides several new signals, i.e., B1C, B2a, B2b and B2a + b, with advanced technologies and global availability, which brings new opportunities for ground-based BDS multipath reflectometry (BDS-MR) altimetry. Previous studies focused on the MR altimetry performance of the legacy signals using signal-to-noise ratio (SNR) observations, but the new BDS signals have not been investigated. In this contribution, all types of BDS-3 SNR data collected from seven International GNSS Service (IGS) stations are analyzed signal by signal in terms of SNR quality and altimetry performance, while the legacy BDS B2I and Global Positioning System (GPS) L2C signals are also selected for comparison. Seven globally distributed IGS stations are first investigated for the quality of SNR observations, and then two optimally selected land stations are used to assess BDS-MR based altimetry performance, while a coastal station is used to assess BDS-MR for sea level retrieval performance. It is found that the quality of SNR observations varied site by site due to the differences in environment and equipment, but in general, the new signals except B1C show a higher level of SNR. Then, no detectable biases among each signal are found for land altimetry, while new signals could yield higher amplitude when performing spectral analysis. In coastal sea level altimetry, only two new signals B1C and B2a are available at the selected IGS station, and it is observed that the retrieval performance of BDS B2a is comparable to that of B2I, B3I and GPS L2C with root-mean-square errors (RMSEs) of about 21 cm, while that for B1I and B1C is slightly poorer with RMSEs of 29.68 cm and 26.66 cm respectively.

覆盖全球的北斗卫星导航系统（BDS-3）于2020年7月31日正式启动。除了区域系统（BDS-2）的传统B1I和B3I信号外，BDS-3还提供了几个新信号，即、B1C、B2a、B2b 和 B2a + b，具有先进的技术和全球可用性，这为地基 BDS 多径反射计 (BDS-MR) 高度测量带来了新机遇。以前的研究侧重于使用信噪比 (SNR) 观测的传统信号的 MR 测高性能，但尚未研究新的 BDS 信号。在这个贡献中，从七个国际 GNSS 服务 (IGS) 站收集的所有类型的 BDS-3 SNR 数据在 SNR 质量和测高性能方面逐个信号地进行分析，同时也选择了传统的 BDS B2I 和全球定位系统 (GPS) L2C 信号进行比较。首先调查全球分布的七个 IGS 站的信噪比观测质量，然后使用两个最佳选择的陆地站评估基于 BDS-MR 的测高性能，同时使用一个沿海站评估 BDS-MR 的海平面反演性能。发现由于环境和设备的不同，SNR观测的质量因站点而异，但总的来说，除B1C之外的新信号表现出更高的SNR水平。然后，对于陆地高度测量，在每个信号之间没有发现可检测的偏差，而在执行频谱分析时，新信号可能会产生更高的幅度。在沿海海平面测高中，选定的 IGS 站只有两个新信号 B1C 和 B2a 可用，