  New methods have been developed for extracting the parameters of diffraction
scattering amplitude, $\sigma_{tot}$ and $\rho=Re F_N/Im F_N$, from
experimental data. The latter determines these parameters with less errors and
without the knowledge of the normalization coefficient. The impact of
additional information from the measurement of the spin-dependence cross
section on the determination of the basic characteristic of elastic scattering
amplitude is examined. The new form of the connection between some
characteristics of the analyzing power and magnitude of the $pp-$ total cross
section is presented.
