The origin reasons of losses in the radar 35D6 speed characteristic (SC) are analyzed. Inconsistency of the pulses repetition periods with properties of the 35D6 original weighting functions applied at digital Fourier transform (FFT) computing is detected. It is shown, that there is no weighting window which would be common and optimal for pulse transmit regimes of radar 35Д6 with equal quantity of pulses. FFT window form optimization by criterion of a SC losses minimum is making. It is gained; that by replacement of 35D6 original weighting functions by the optimal decrease of losses to 7% – 16% is possible (depending on the meteorological situation). Thus, for each pulse transmit regime it is necessary to use a separate weighting function.
Discrete Fourier transform, weighting function, filter, speed characteristic, losses