We present two different approaches to broadcasting information to retrieve the GNSS-to-GNSS time offsets needed by users of multi-GNSS signals. Both approaches rely on the broadcast of a single time offset of each GNSS time versus one common time scale instead of broadcasting the time offsets between each of the constellation pairs. The first common time scale is the average of the GNSS time scales, and the second time scale is the prediction of UTC already broadcast by the different systems. We show that the average GNSS time scale allows the estimation of the GNSS-to-GNSS time offset at the user level with the very low uncertainty of a few nanoseconds when the receivers at both the provider and user levels are fully calibrated. The use of broadcast UTC prediction as a common time scale has a slightly larger uncertainty, which depends on the broadcast UTC prediction quality, which could be improved in the future. This study focuses on the evaluation of two different common time scales, not considering the impact of receiver calibration, at the user and provider levels, which can nevertheless have an important impact on GNSS-to-GNSS time offset estimation.

我们提出了两种不同的广播信息检索方法，以检索多GNSS信号用户所需的GNSS到GNSS时间偏移。两种方法都依赖于每个GNSS时间相对于一个公共时间标度的单个时间偏移量的广播，而不是广播每个星座对之间的时间偏移量。第一个公共时间标度是GNSS时间标度的平均值，第二个时间标度是不同系统已经广播的UTC的预测。我们显示，当在提供者和用户级别的接收器都经过全面校准时，平均GNSS时间标度允许在用户级别估计GNSS到GNSS的时间偏移，而不确定性仅为几纳秒。使用广播UTC预测作为常见时间尺度时，不确定性会稍大一些，这取决于广播UTC预测质量，将来可能会提高。这项研究的重点是在用户和提供商层面评估两个不同的通用时间尺度，而不考虑接收机校准的影响，但这可能会对GNSS到GNSS的时间偏移量估计产生重要影响。