Numb .obs -- the number of group delay observables used in solution.
In the case if X/S solution one observable is a linear combination of
X-band and S-band group delay at one baseline during one scan. In the
case of X-band or S-band solution one observable is a group delay
at X-band or S-band one baseline during one scan. Some observables
may be deselected from the solution if fringe fitting process failed
to find the main maximum in delay resolution function.