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.