The distribution of clock correction and ephemeris (CCE) parameters in navigation messages broadcast by operational satellite vehicles (SVs) of the Global Navigation Satellite System (GNSS) is studied. For this purpose, two evaluation metrics are proposed, namely atypical navigation message structures and time to complete CCE sets (TTCS). The evaluation metrics are used to analyze three and a half years of operational Galileo F/NAV and GPS LNAV messages. The study considers arbitrary and healthy-only signal-in-space (SIS) health statuses. The frequently used receiver independent exchange format (RINEX) navigation files are shown to not provide sufficient information to determine the CCE parameters transmitted at every time instance. Due to the identified limitations, binary navigation data collected by a worldwide network of monitoring stations are used for the analysis. During operations, the maximum of the TTCS metric is shown to be impacted by the issue of data (IOD) update periods and structures with mismatched IOD parameters, potentially introducing an additional delay to the time to first fix (TTFF). The message timing requirements of dual-frequency multi-constellation (DFMC) satellite-based augmentation system (SBAS) are shown to be in line with the minimum times needed to obtain multiple complete Galileo F/NAV and GPS LNAV CCE sets.

研究了全球导航卫星系统 (GNSS) 的运营卫星车辆 (SV) 广播的导航电文中时钟校正和星历 (CCE) 参数的分布。为此，提出了两个评估指标，即非典型导航消息结构和完成 CCE 集的时间 (TTCS)。评估指标用于分析三年半运行的伽利略 F/NAV 和 GPS LNAV 消息。该研究考虑了任意和仅健康的空间信号 (SIS) 健康状态。常用的接收器独立交换格式 (RINEX) 导航文件没有提供足够的信息来确定在每个时间实例传输的 CCE 参数。由于确定的局限性，由全球监测站网络收集的二进制导航数据用于分析。在操作期间，TTCS 指标的最大值显示受数据 (IOD) 更新周期问题和 IOD 参数不匹配的结构的影响，可能会导致首次修复时间 (TTFF) 的额外延迟。双频多星座 (DFMC) 星基增强系统 (SBAS) 的消息定时要求显示符合获得多个完整伽利略 F/NAV 和 GPS LNAV CCE 集所需的最小时间。