  We present results of observation of Cygnus-A radiosource scintillation in
the Earth's ionosphere in quiet and disturbed geomagnetic condition at Irkutsk
incoherent scattering radar (IISR). Scintillation method applied for ionosphere
testing at IISR confidently defines Fresnel frequency and power cutoff - the
spectral characteristics usually related to the velocities and spatial spectra
of ionospheric plasma irregularities. We also use IGFR magnetic field model in
order to show relation between shape of discrete radio source scintillation
spectra and direction to the radio source with respect to geomagnetic field.
Observed increasing of S4 index in magnetic zenith is conditioned by the
scintillation spectrum widening. We also evaluate zonal velocity of observed
ionospheric irregularities as ~10 m/sec assuming irregularities to appear at
the height of F2 layer maximum of the ionosphere.
