how I can get the posterior covariance matrix after baseline processing

[harishchavandke01]

Currently, I am reading .pos file and calculating the covariance matrix but it is giving too optimistic values (too small values). I also compared same data in Trimble business center. but values of TBC of covariance matrix comparing ~1000 time rtklib values.

I am calculating this correctly ? or TBC using some different logic to calculate it ?
Thank you!

[rtklibexplorer]

The covariance matrix output of the Kalman filter will always be optimistic because of its assumption that all input errors are gaussian, zero mean, uncorrelated to other measurements, and uncorrelated in time. However, 1000 times smaller seems like a lot. I did a very simple analysis of the diagonal terms of the covariance matrix in this post, and did not see such large discrepancies.