In safety-critical applications, such as the Ground-Based Augmentation System for precision approaches in civil aviation, it is important to safeguard users under the case of ephemeris failures. For CAT II/III approaches, different ephemeris monitors with approaches for ambiguity resolution are proposed with the double differenced carrier phase as the test statistics. The continuity risks introduced by the ambiguity resolution are addressed by deriving the required averaging time for new, acquired, and re-acquired satellites. Since the ephemeris fault is closely related with the baseline length between ground stations, the minimum baseline length is derived to meet the probability of missed detection region. Current methods are compared with both the averaging time and the ground baseline length. It is demonstrated that a combination of two methods is able to achieve the best performance with 94 averaging epochs and 218 m ground baseline length.

在对安全至关重要的应用中，例如在民航中采用精确进近的地面增强系统，在星历表故障的情况下保护用户非常重要。对于CAT II / III方案，提出了具有歧义解决方案的不同星历监视器，并以双差载波相位作为测试统计量。通过得出新的，获取的和重新获取的卫星所需的平均时间，可以解决歧义解决方案引入的连续性风险。由于星历断层与地面站之间的基线长度密切相关，因此得出了最小基线长度以满足丢失检测区域的可能性。将当前方法与平均时间和地面基线长度进行比较。