The accuracy assessment of terrestrial reference frames (TRFs) at coordinate system level is a key task to ensure their successful use in Earth studies, satellite navigation and other geodetic positioning applications. Currently, the TRF quality specifications for the most demanding users dictate that the origin, orientation and scale should be determined at an accuracy level of 1 mm, and they should remain stable over time at a rate of 0.1 mm/yr. To evaluate the conformity of the internal accuracy of modern TRFs to such requirements, an appropriate mapping is needed to convert frame coordinate errors (and their CV matrix) in a terrestrial network to matching errors (and their CV matrix) in the realized coordinate system. Several projection schemes may be considered for this mapping problem, all of which aim at extracting the correlated part of the estimation error in TRF coordinates that is describable by small random perturbations in their coordinate system. The goal of the present paper is to investigate the inference problem of frame accuracy at coordinate system level, and to discuss not only the theoretical aspects of the required covariance projectors, but also the practical impact on the results obtained by their implementation in space geodetic solutions. For this purpose, a relevant case study is performed to evaluate the accuracy of the realized origin, orientation and scale in the ITRF frame series based on the formal CV matrices for their estimated positions and velocities in the four technique subnetworks (DORIS, SLR, VLBI, GNSS).

坐标系层面的地球参考系（TRF）精度评估是确保其在地球研究、卫星导航和其他大地测量定位应用中成功使用的一项关键任务。目前，针对最苛刻用户的 TRF 质量规范规定，原点、方向和比例应以 1 毫米的精度水平确定，并且随着时间的推移，它们应以 0.1 毫米/年的速度保持稳定。为了评估现代 TRF 的内部精度是否符合此类要求，需要适当的映射将地面网络中的帧坐标误差（及其 CV 矩阵）转换为已实现的坐标系中的匹配误差（及其 CV 矩阵）。对于这个映射问题可以考虑几种投影方案，所有这些方案都旨在提取 TRF 坐标中估计误差的相关部分，该部分可以通过其坐标系中的小随机扰动来描述。本文的目标是研究坐标系级别的框架精度的推断问题，不仅讨论所需协方差投影仪的理论方面，而且讨论它们在空间大地测量解决方案中实现所获得的结果的实际影响。为此，进行了相关案例研究，以基于四种技术子网（DORIS、SLR、VLBI）中估计位置和速度的形式 CV 矩阵来评估 ITRF 框架系列中实现的原点、方向和比例的准确性。 ，全球导航卫星系统）。