Observable quality assessment of broadband very long baseline interferometry system

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 observations from 2017 to 2019. We quality assessments for two kinds observables in the 21 sessions currently available: group delay differential total electron content ($\delta$TEC). Our study reveals that random measurement noise delays at level less than 2 ps (1 = 10$^{-12}$ s), while contributions systematic error sources, mainly source structure related, are 20 ps. Due significant improvement noise, effects relatively magnitudes not overwhelming S/X VLBI instance 10 ps, clearly visible observations. Another critical discrete jumps, instance, offset about 310 or integer multiples that. predominant causative factor found be related structure. $\delta$TEC 0.07 TECU, but five times larger A strong correlation between discovered trend 40 ps/TECU large effects; there second range 60 70 when dominant.