The next-generation, broadband geodetic very long baseline interferometry system, named VGOS, is developing its global network, and VGOS networks with a small size of 3–7 stations have already made broadband observations from 2017 to 2019. We made quality assessments for two kinds of observables in the 21 VGOS sessions currently available: group delay and differential total electron content (\(\delta \)TEC). Our study reveals that the random measurement noise of VGOS group delays is at the level of less than 2 ps (\(1\,\hbox {ps}\,=\,10^{-12}\) s), while the contributions from systematic error sources, mainly source structure related, are at the level of 20 ps. Due to the significant improvement in measurement noise, source structure effects with relatively small magnitudes that are not overwhelming in the S/X VLBI system, for instance 10 ps, are clearly visible in VGOS observations. Another critical error source in VGOS observations is discrete delay jumps, for instance, a systematic offset of about 310 ps or integer multiples of that. The predominant causative factor is found to be related to source structure. The measurement noise level of \(\delta \)TEC observables is about 0.07 TECU, but the systematic effects are five times larger than that. A strong correlation between group delay and \(\delta \)TEC observables is discovered with a trend of 40 ps/TECU for observations with large structure effects; there is a second trend in the range 60–70 ps/TECU when the measurement noise is dominant.

名为VGOS的下一代宽带大地测量甚长基线干涉仪系统正在开发其全球网络，而从3到7个站点的小型VGOS网络已在2017年至2019年进行了宽带观测。我们对两个系统进行了质量评估当前可用的21个VGOS会话中的各种可观测值：群延迟和差分总电子含量（\（\ delta \） TEC）。我们的研究表明，VGOS群延迟的随机测量噪声小于2 ps（\（1 \，\ hbox {ps} \，= \，10 ^ {-12} \） s），而系统误差源（主要是与源结构有关）的贡献为20 ps。由于测量噪声的显着改善，在VGOS观测中可以清楚地看到在S / X VLBI系统中不占优势的相对较小幅度的源结构效应，例如10 ps。VGOS观测中的另一个关键误差源是离散的延迟跳跃，例如，约310 ps的系统偏移或其整数倍。发现主要的致病因素与源结构有关。\（\ delta \） TEC观测值的测量噪声水平约为0.07 TECU，但系统影响是该值的五倍。组延迟与\（\ delta \）之间有很强的相关性发现TEC可观测物的趋势为40 ps / TECU，可用于具有较大结构影响的观测。当测量噪声占主导地位时，在60–70 ps / TECU范围内存在第二种趋势。