I.F. Kupryashkin

In operation questions of influence of relaying noises on estimate errors bearing small object under its radar image generated by a SAR are considered. Thus it is necessary, that with a view of improvement of quality of the image in SAR one of algorithms of autofocusing most often used in practice - phase gradient algorithm is applied. The operation purpose is reception of dependence of bias of an estimate bearing object from a degree of a defocusing of the relayed signal at various working conditions phase gradient algorithm of autofocusing. For achievement of the specified purpose in article the expressions are gained, allowing to estimate probability of excess by level defocused a false mark of level of the focused image of dot object. Thus it was necessary, that the view of phase contortions of the relayed signal is picked purposely up so that to provide the peak bias of the true mark at failure of normal operation of algorithm phase gradient autofocusings. Use of the gained expressions and the dependences constructed on their bottom has allowed to erect, that failure of operation of algorithm phase gradient autofocusings (which sign achievement by estimate bias bearing the value exceeding azimuthal resolution SAR) serves comes in a case when the mean power of the relayed signal on 10 and more decibels exceeds a mean power of a signal.