Guyennon Nicolas, Cerretto Giancarlo, Tavella Patrizia, Lahaye François
Time and Frequency Metrology Department, Istituto Nazionale di Ricerca Metrologica (INRiM), Torino, Italy.
IEEE Trans Ultrason Ferroelectr Freq Control. 2009 Aug;56(8):1634-41. doi: 10.1109/TUFFC.2009.1228.
In recent years, many national timing laboratories have installed geodetic Global Positioning System receivers together with their traditional GPS/GLONASS Common View receivers and Two Way Satellite Time and Frequency Transfer equipment. Many of these geodetic receivers operate continuously within the International GNSS Service (IGS), and their data are regularly processed by IGS Analysis Centers. From its global network of over 350 stations and its Analysis Centers, the IGS generates precise combined GPS ephemeredes and station and satellite clock time series referred to the IGS Time Scale. A processing method called Precise Point Positioning (PPP) is in use in the geodetic community allowing precise recovery of GPS antenna position, clock phase, and atmospheric delays by taking advantage of these IGS precise products. Previous assessments, carried out at Istituto Nazionale di Ricerca Metrologica (INRiM; formerly IEN) with a PPP implementation developed at Natural Resources Canada (NRCan), showed PPP clock solutions have better stability over short/medium term than GPS CV and GPS P3 methods and significantly reduce the day-boundary discontinuities when used in multi-day continuous processing, allowing time-limited, campaign-style time-transfer experiments. This paper reports on follow-on work performed at INRiM and NRCan to further characterize and develop the PPP method for time transfer applications, using data from some of the National Metrology Institutes. We develop a processing procedure that takes advantage of the improved stability of the phase-connected multi-day PPP solutions while allowing the generation of continuous clock time series, more applicable to continuous operation/monitoring of timing equipment.
近年来，许多国家计时实验室已安装了大地测量全球定位系统（GPS）接收机，以及传统的GPS/GLONASS共视接收机和双向卫星时间频率传递设备。这些大地测量接收机中的许多在国际全球导航卫星系统服务（IGS）内连续运行，其数据由IGS分析中心定期处理。IGS通过其由350多个站点组成的全球网络及其分析中心，生成精确的组合GPS星历以及相对于IGS时间尺度的站点和卫星时钟时间序列。大地测量领域正在使用一种称为精密单点定位（PPP）的处理方法，该方法通过利用这些IGS精确产品，能够精确恢复GPS天线位置、时钟相位和大气延迟。此前，意大利国家计量研究院（INRiM；前身为IEN）利用加拿大自然资源部（NRCan）开发的PPP实施方案进行的评估表明，PPP时钟解在短期/中期具有比GPS共视和GPS P3方法更好的稳定性，并且在多日连续处理中使用时可显著减少日边界不连续性，从而允许进行限时的、类似活动的时间传递实验。本文报告了INRiM和NRCan开展的后续工作，以利用一些国家计量机构的数据，进一步表征和开发用于时间传递应用的PPP方法。我们开发了一种处理程序，该程序利用了相位连接的多日PPP解的更高稳定性，同时允许生成连续的时钟时间序列，更适用于计时设备的连续运行/监测。
