The article based on the method of statistical frequency stabilization deals with the issues of increasing frequency stability and synchronization of the forming HF signals in a transmitting device of a localizer using a multichannel variant of construction. It was demonstrated that the available digital unit of frequency and phase correction allows easy application of the proposed method. Two main features of the localizer operation affecting frequency stability and phase synchronization of HF signals are noted. The first factor is determined by deviation of the present -HF signal frequency (on the measurement interval) from the average (i) frequency value in n-channel. The second one is related to average frequency variation of each of the forming HF signals and its deviation within the (i) value from the nominal value during localizer operation. On the basis of HF signals description in channels of the transmitting device of a localizer ratios are obtained determining optimal values in terms of the method of least square method as (i) deviations of the present frequency values from the average value as well as variations of average frequency values during localizer operation. The article considers the most significant, from an applicatory point of view, case of assessment covering only deviations of the present HF signals frequency values from the average value on the measurement interval. It is shown that application of the method of statistical frequency stabilization allows the transmitting device of a localizer including N channels of HF signals formation to increase frequency stability and HF signals phase synchronization times. That enables to improve accuracy of forming integrated and difference directivity diagrams and setting heading in the runway direction as well. Apart from that, on the basis of the received values of frequency parameters estimation and relative instability of the forming HF signals a decision can be made about the condition of the controlled parameter by the criterion STANDARD-DETERIORATION-ACCIDENT.

Рассмотрены возможности использования импедансных покрытий для уменьшения уровня бокового и заднего излучения антенной системы. На примере дуговой антенной решетки продольных щелевых излучателей получены оценки снижения уровня бокового и заднего излучения при использовании поверхностей с емкостным характером импеданса. Дано сравнение с результатами, полученными на основе реализации спадающего амплитудно-фазового распределения в антенне без использования импедансных покрытий.

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Introduction. This paper is devoted to the development of a method for estimating the current  time-frequency parameters of each of a set of simultaneously and independently operating generators in the radio electronic system. A general case is considered, in which the deviation of true values of the nominal generator parameters from the assumed values of these parameters is determined not only by random, but also by long-term frequency deviation. The work objective is to generalize the method for estimating the time-frequency parameters of signals (long-term nominal frequency and current frequency deviation from the nominal value) based on the simultaneous measurement of the phases of signals generated in the system of independently functioning generators. The research task is to consider a system of simultaneously and independently operating generators. Each of them generates harmonic signals, whose time-frequency parameters, such as the average frequency, are constant during a certain interval of observation. But herewith, these time-frequency parameters are known with insufficient accuracy due to the influence of external factors (changes in temperature, pressure, supply voltage, etc.). It is required to obtain estimates of the time-frequency parameters of signals (the duration of the measuring interval, values of the long-term frequency and the standard deviation) from the results of measurements of the phases of signals formed by the generators at measuring intervals belonging to the observation interval, within which the average frequency remains constant.Materials and Methods. A system of simultaneously and independently functioning generators is considered. The long- term value of signal frequency for each of the generators over the observation interval remains constant, but it is known with some margin of error. During the observation interval, several measurements of the signal phase of each of the generators are performed. At the same time, the current values of the signal frequency and the duration of the measuring interval have random deviations from the long-term values, and follow the normal distribution law with zero mathematical expectation and a known variance. The estimation of time-frequency parameters based on the results of measuring the signal phases is carried out using a multidimensional likelihood function. The maximum is found on the base of solving the redefined system of linear algebraic equations.Results. A new mathematical model and a numerical-analytical method for determining the time-frequency parameters of signals are developed. They take into account both the long-term constant frequency deviation and short-term random deviations.Discussion and Conclusions. The results obtained can be used under the development and creation of data-measuring and information-telecommunication systems, including geographically distributed systems. The resulting estimates of the time-frequency parameters enable to increase the signal frequency stability and, accordingly, to improve the accuracy of measurements and the quality of information transfer.

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