  The Quark Gluon String Model (QGSM) reproduces well the global
characteristics of the $pp$ collisions at RHIC and LHC, e.g., the
pseudorapidity and transverse momenta distributions at different centralities.
The main goal of this work is to employ the Monte Carlo QGSM for description of
femtoscopic characteristics in $pp$ collisions at RHIC and LHC. The study is
concentrated on the low multiplicity and multiplicity averaged events, where no
collective effects are expected. The different procedures for fitting the
one-dimensional correlation functions of pions are studied and compared with
the space-time distributions extracted directly from the model. Particularly,
it is shown that the double Gaussian fit reveals the contributions coming
separately from resonances and from directly produced particles. The comparison
of model results with the experimental data favors decrease of particle
formation time with rising collision energy.
