V.M. Davidochkin - Ph.D. (Eng.), Head of Department «Microwave Devices and Antennas», ООО enterprise «Contact 1». E-mail: skb@kontakt-1.ru
V.V. Ezerskiy - Dr.Sc. (Eng.), Professor, Department «Radio Communication», Ryazan State Radio Engineering University. E-mail: ezerski@yandex.ru

In monitoring systems and managements of technological processes of filling of tanks are widely used radar-tracking methods of measurement of distance. It is promoted by absence of direct contact of the measuring device with tank contents, split-hair accuracy of measurements and weak, easily considered dependence on external conditions. For radio range finders the most essential obstacle of reception of a low error of measurements are parasitic an echo - signals. The errors caused by hindrances, the reflexions caused, in particular, from elements of a design of the tank and from discontinuity antenna-waveguide path (AWP) are considered. Heterogeneity in AWP can create similar to a signal the hindrances by the form coinciding with a useful signal and pulse hindrances, caused by excitation of the higher types of waves. It is shown that essential impact makes on a measurement error a kind of weight functions (WF), signals used at processing, both in time, and in spectral areas. For objective choice WF in problems of an estimation of frequency of a signal it is offered to connect width of the basic petal and level of lateral petals (LLP) spectral density of amplitudes WF with a margin error estimations of frequency of a signal. For this purpose in the known system of parameters, characterizing spectral properties WF, the additional parameter - a relative error of an estimation of frequency is entered. The size of a relative error of an estimation of frequency is defined, how the module of the relation of a bending around current error of an estimation of frequency at use analyzed WF to the maximum value of an error of an estimation of frequency at use uniform WF. Dependence of a relative error of an estimation of frequency has two cores and sequence of lateral petals. A number widely known WF is analyzed. It is shown that reduction of maxima of the basic petals of a relative error is accompanied by inevitable growth LLP. At the set admissible value of an error the increase in speed of decrease in lateral petals also leads to growth LLP of a relative error. It is shown that among widely known WF the least LLP a relative error of an estimation of frequency at any values of a maximum of the basic petal has WF Dolf-Chebyshev. WF Dolf-Chebyshev has LLP dependences of a relative error of an estimation of frequency less on 12 dB and more, than WF Kaiser-Bessel. However, not fading character of lateral petals of a spectrum of WF Dolf-Chebyshev leads to poorly fading lateral petals of dependence of a relative error of an estimation of frequency that limits advantage of WF Dolf-Chebyshev to a scope for the analysis of signals with small number of readout.