  The top quark pair production and decay are considered in the framework of
the smeared-mass unstable particles model. The results for total and
differential cross sections in vicinity of $t\bar{t}$ threshold are in good
agreement with the previous ones in the literature. The strategy of
calculations of the higher order corrections in the framework of the model is
discussed. Suggested approach significantly simplifies calculations compared to
the standard perturbative one and can serve as a convenient tool for fast and
precise preliminary analysis of processes involving intermediate time-like top
quark exchanges in the near-threshold region.
