RU2525829C1 - Radar method of detecting law of variation of angular velocity of turning of tracked aerial object based on successively received signal reflections with carrier frequency adjustment - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: method comprises generating and using a trajectory characteristic which is a relationship indicating change in the sum of differences of complex amplitudes of adjacent range portraits from the portrait number, i.e. from the time of receiving the next fraction of signals with carrier frequency adjustment, wherein five-fold smoothing out of the initial characteristic via a moving average method is proposed to construct a higher-quality trajectory characteristic of the aerial object.

EFFECT: high noise-immunity of a prospective multi-frequency mode of radar tracking and creating radar images of objects.

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Description

The invention relates to radar methods and can be used in systems for the classification and identification of airborne objects using the principle of averaging the attribute of belonging when changing the angle of the object, as well as in systems for constructing radar images of objects using the inverse aperture synthesis method.

In the first of the indicated systems, it is necessary to use the interval within which the tracked object changes its orientation with respect to the line of sight to the maximum, and in the radar imaging systems, the interval at which the angular velocity of rotation of the object is the result of only (exclusively) moving the center of mass along a straight path and not associated with the manifestation of trajectory flight instabilities, i.e. yaw, roll and pitch fluctuations of the glider.

сопровождаемого воздушного объекта (летательного аппарата) по последовательно принятым отражениям одночастотных сигналов, входящий в структуру способа формирования двумерного радиолокационного изображения [1]. Known radar method for detecting the law of change in the angular velocity of rotation $$F\left(\dot{\gamma }\right)$$

accompanied by an air object (aircraft) by sequentially received reflections of single-frequency signals, included in the structure of the method of forming a two-dimensional radar image [1].

заключается в том, что в направлении воздушного объекта излучают последовательности сигналов с перестройкой несущей частоты из 2^N импульсов (N=8,9) каждая, частоту этих импульсов изменяют от импульса к импульсу в диапазоне от f₀ до (f₀+F_пер), где f₀ - основная (начальная) несущая частота квазиоптической области отражения сантиметрового диапазона, F_пер - диапазон, в котором осуществляется перестройка частоты от импульса к импульсу с интервалом Δf=F_пер/(2^N-1). Затем принимают отраженные от летательного аппарата (ЛА) сигналы. По принятым отраженным сигналам сопровождают ЛА по угловым координатам и дальности, записывают в оперативное запоминающее устройство (ОЗУ) амплитуды и фазы, а также номер и время приема отраженных сигналов с перестройкой несущей частоты (СПНЧ), причем регистрацию или запись этих данных проводят на интервале времени Т₃, на порядок превышающем величину 2^2NT_и, где T_и - период повторения импульсов, а излучение каждой последовательности с перестройкой частоты из 2^N импульсов проводят в течение интервала времени Т_посл, не превышающего 5 мс, т.е. в течение времени, практически на порядок меньшего продолжительности интервала корреляции траекторных нестабильностей полета ЛА. При этом в целях обеспечения помехозащищенности частоту импульсов каждой последовательности из 2^N импульсов изменяют по уникальному случайному закону, выполняя, однако, условие, чтобы в пределах каждой 2^N-импульсной последовательности частота каждого импульса повторялась только один раз. The essence of this method of revealing the law $$F\left(\dot{\gamma }\right)$$

consists in the fact that in the direction of the airborne object they emit sequences of signals with a tuning of the carrier frequency of 2 ^N pulses (N = 8.9) each, the frequency of these pulses is changed from pulse to pulse in the range from f ₀ to (f ₀ + F _per ) where f ₀ is the main (initial) carrier frequency of the quasi-optical reflection region of the centimeter range, F _per is the range in which the frequency is tuned from pulse to pulse with the interval Δf = F _per / (2 ^N -1). Then receive the signals reflected from the aircraft (LA). According to the received reflected signals, the aircraft is accompanied by angular coordinates and range, recorded in the random access memory (RAM) of the amplitude and phase, as well as the number and time of reception of the reflected signals with the tuning of the carrier frequency (SPFC), and registration or recording of these data is carried out on a time interval T ₃ , an order of magnitude greater than 2 ^2N T _and , where T _and is the pulse repetition period, and the radiation of each sequence with a frequency tuning of 2 ^N pulses is carried out during the time interval T _last not exceeding 5 ms, i.e. . over time, almost an order of magnitude shorter duration of the correlation interval of trajectory flight instabilities of the aircraft. Moreover, in order to ensure noise immunity, the frequency of the pulses of each sequence of 2 ^N pulses is changed according to a unique random law, however, satisfying the condition that within each 2 ^N- pulse sequence the frequency of each pulse is repeated only once.

The first pulse in each sequence with frequency tuning is the pulse at a frequency f ₀ . After receiving, converting from analog to digital form and writing to the RAM the parameters of the reflected signals, a rectangular two-dimensional data array is formed, referred to as a multi-frequency synthesized scattering matrix (MSSR), for which, within each sequence of the SPNC, the registered data are rearranged in RAM, providing them sequential arrangement in the columns of the MMR in the order of a monotonic increase in frequency from f ₀ to (f ₀ + F _per ). As a result, a two-dimensional data array is obtained, the columns of which are arranged in accordance with the numbers of the transmitted (and correspondingly received) TPS sequences, and the data in the columns are not arranged in random order of emission, but in the order of a monotonic change in the radiation frequency from f ₀ to (f ₀ + F _per ). Thus, in each row of the array, the amplitudes and phases of the signals of the same frequency are arranged.

. Далее в отдельный массив M₁₂ записывают параметры отражений на первой частоте f₀, формируя таким образом цифровую отражательную характеристику ЛА из M элементов M=T_з/T_и. Выборку эквидистантных значений отраженных сигналов на частоте f₀ на интервале запоминания T_з называют генеральной, а любую выборку из взятых подряд по времени приема 2^N значений в пределах генеральной выборки называют частной выборкой, при этом i-й частной выборкой (ЧВ) называют выборку, первый элемент которой соответствует i-му элементу массива M₁₂, т.е. i-му элементу генеральной выборки (ГВ). Вычисляют коэффициенты корреляции между смежными по номерам ЧВ, т.е. между 1-й и 2-й, между 2-й и 3-й, между 3-й и 4-й и т.д. Каждому i-му коэффициенту корреляции ρ_i ставят в соответствие момент времени, соответствующий середине интервала, на котором получены отражения для i-й ЧВ. The data on the reflected signals are written into the elements of the MSSR in a complex form, namely, after receiving each m-th packet of the SPSF from the amplitude Δ _k and phase φ _{k of the} k-th reflected pulse, the complex value of this reflected pulse is formed in the form $${\dot{A}}_k=A_k{e}^{j{\varphi }_k}$$

. Next, in a separate array M ₁₂ write the reflection parameters at the first frequency f ₀ , thus forming a digital reflective characteristic of the aircraft from M elements M = T _s / T _and . A sample of equidistant values of the reflected signals at a frequency f ₀ in the memory interval T _s is called a general sample, and any sample of 2 ^N values taken consecutively at the reception time within the general sample is called a private sample, while the ith private sample (CV) is called a sample, the first element of which corresponds to the ith element of the array M ₁₂ , i.e. i-th element of the general sample (GW). The correlation coefficients between adjacent by the numbers of the FW are calculated, i.e. between 1st and 2nd, between 2nd and 3rd, between 3rd and 4th, etc. Each i-th correlation coefficient ρ _i is associated with a moment of time corresponding to the middle of the interval in which reflections for the i-th FW are obtained.

максимальна, и наоборот. Зависимость КК от времени t считают косвенной (т.е. не имеющей строгой аналитической связи с $$\dot{\gamma }$$

) зависимостью угловой скорости $$\dot{\gamma }$$

от времени t, которую и воспринимают в качестве закона $$F\left[\dot{\gamma }\left(t\right)\right]$$

изменения $$\dot{\gamma }$$

с течением времени.The result is (M-2 ^N -1) correlation coefficients (CC) ρ and their corresponding time points, which are stored in the corresponding elements of the array D ₁ RAM. Analyze the information recorded in the array D ₁ and find in them a point in time corresponding to the minimum QC or maximum QC. In accordance with the physical meaning of the spacecraft, it is believed that at the time when the spacecraft is minimal, the angular velocity of rotation of the aircraft $$\dot{\gamma }$$

maximum and vice versa. The dependence of QC on time t is considered indirect (i.e., it does not have a strict analytical relationship with $$\dot{\gamma }$$

) the dependence of the angular velocity $$\dot{\gamma }$$

from time t, which is taken as a law $$F\left[\dot{\gamma }\left(t\right)\right]$$

changes $$\dot{\gamma }$$

over time.

изменения угловой скорости $$\dot{\gamma }$$

не может быть признан эффективным и надежным, т.к. время между одночастотными излучаемыми сигналами имеет согласно способу жесткую зависимость от длительности Т_посл последовательности (пачки) СПНЧ. В работе [2] для получения правдоподобных значений оценочного КК (по которым в ходе обработки данных натурных экспериментов были получены пригодные для использования корреляционные характеристики $$P\left(\dot{\gamma }\right)$$

разных ЛА) рекомендовано использовать период повторения одночастотных сигналов, не превосходящий 1 мс. Это сильно усложняет способ формирования РЛИ, в интересах которого производится извлечение закона $$F\left[\dot{\gamma }\left(t\right)\right]$$

. Причина в том, что последовательности СПНЧ, как правило, по длительности превосходят 1 мс. Например, для пачек из 128 сигналов при T_и=30 мкс периодичность повторения сигналов первой частоты f₀ составляет 7,7 мс. А если применять перестройку частоты от пачки к пачке (вместо перестройки от импульса к импульсу) и использовать накопление в коротких одночастотных пачках, то длительность последовательности пачек с перестройкой частоты еще более возрастает. Значит, для реализации корреляционного алгоритма выявления закона $$F\left[\dot{\gamma }\left(t\right)\right]$$

[1] придется дополнительно излучать сигналы основной частоты f₀ внутри (в пределах) последовательности сигналов N частот. Это, во-первых, нарушит эквидистантность СПНЧ, а во-вторых, снизит помехоустойчивость режима сопровождения, т.к. сигналы с частотой f₀ будут использоваться чаще и возникнет угроза постановки прицельной помехи на первой частоте f₀.The method for revealing the law proposed in [1] $$F\left[\dot{\gamma }\left(t\right)\right]$$

changes in angular velocity $$\dot{\gamma }$$

cannot be recognized as effective and reliable, because the time between single-frequency emitted signals according to the method has a strict dependence on the duration T of the _last sequence (packet) of SPNCH. In [2], to obtain plausible values of the estimated CC (from which, in the course of processing data from field experiments, correlation characteristics suitable for use were obtained $$P\left(\dot{\gamma }\right)$$

different aircraft) it is recommended to use the repetition period of single-frequency signals, not exceeding 1 ms. This greatly complicates the method of forming radar images, in the interests of which the law is extracted. $$F\left[\dot{\gamma }\left(t\right)\right]$$

. The reason is that HPS sequences tend to exceed 1 ms in duration. For example, for bursts of 128 signals at T _and = 30 μs, the frequency of repetition of the signals of the first frequency f ₀ is 7.7 ms. And if frequency tuning from burst to burst is used (instead of burst-to-burst trimming) and using accumulation in short single-frequency bursts, then the duration of the burst sequence with frequency tuning increases even more. So, for the implementation of the correlation algorithm for revealing the law $$F\left[\dot{\gamma }\left(t\right)\right]$$

[1] will have to additionally emit signals of the fundamental frequency f ₀ inside (within) the sequence of signals of N frequencies. This, firstly, will violate the equidistance of the SPNCH, and secondly, it will reduce the noise immunity of the tracking mode, as signals with a frequency f ₀ will be used more often and there will be a threat of setting impact interference at the first frequency f ₀ .

. Собственно говоря, известный способ выявления угловой скорости $$\dot{\gamma }$$

[1] и был предложен в виду отсутствия возможности получения закона $$F\left(\dot{\gamma }\right)$$

по отраженным СПНЧ. И наконец, эквидистантность сигналов на частоте f₀ в [1], снижающая помехоустойчивость, также обусловлена необходимостью получения одночастотной отражательной характеристики. Отсутствие такой необходимости позволяет осуществлять перестройку частоты в пределах последовательности по случайному закону для всех без исключения сигналов, а не для (2^N-1) сигналов, кроме сигналов на частоте f₀, которые предложено всегда в каждой пачке СПНЧ использовать первыми.Another significant drawback of the prototype method [1] is the inability to increase the signal-to-noise ratio due to the coherent addition of signals before the formation of a single-frequency reflective characteristic of the aircraft in the form of an array of M ₁₂ . The use of frequently repeating bursts of signals at a frequency f ₀ will further reduce noise immunity and increase the duration of the TPS sequence T _last , which will significantly complicate the processing of signals. In interference and noise, the reflective characteristic of an aircraft at a frequency f ₀ cannot expressively maximize and minimize $$\dot{\gamma }$$

. In fact, a known method for detecting angular velocity $$\dot{\gamma }$$

[1] and was proposed in view of the lack of the possibility of obtaining a law $$F\left(\dot{\gamma }\right)$$

according to reflected SPS. And finally, the equidistance of signals at a frequency f ₀ in [1], which reduces the noise immunity, is also due to the need to obtain a single-frequency reflective characteristic. The absence of such a need makes it possible to carry out frequency tuning within the sequence according to a random law for all signals without exception, and not for (2 ^N -1) signals, except for signals at a frequency f ₀ , which are always proposed to be used first in each packet of SPNC.

The objective of the invention is to develop a method for detecting the law of change in the angular velocity of rotation of an aircraft relative to the line of sight with sequential radiation of fractions of the SPNCH without organizing more frequent radiation of single-frequency signals, since such radiation reduces the noise immunity of a promising multi-frequency mode of radar tracking and the formation of radar information.

To solve this problem, it is proposed to use the fact that the amplitude-phase fluctuations of the signals reflected by the aircraft become more intense with an increase in the angular velocity of rotation of the accompanied aircraft. However, other factors affecting the degree of fluctuation of radar reflections should be neutralized. These factors include the radial approach (removal) of an aircraft to a radar station (radar), turboprop modulation of the reflected signals and the presence of noise (interference) of arbitrary origin. Therefore, it is necessary to build a system for processing the reflected signals in such a way as to minimize the influence of negative factors and effectively highlight useful fluctuations associated exclusively with the turns of the aircraft relative to the radar line of sight.

First of all, we consider the procedure for eliminating negative factors, and then check the possibility of distinguishing the intensity of aircraft turns by the corresponding intensity of the amplitude-phase fluctuations of the reflected signals.

It is known [3, 4] that the approximation or removal of objects of reflection of radio waves does not affect the amplitude of the reflected signals, but introduces phase additions that are multiples of the fractional part of the wave number 2π / λ, where λ is the wavelength (for a combined radar due to the double course of the electromagnetic wave it should be a fraction of the number 4π / λ). Therefore, in the first step, it is necessary to calculate the radial speed of the aircraft and eliminate the phase changes in the received signals associated with the change in the distance to the aircraft.

после получения ДлП ЛА.The negative effect of noise and distributed obstruction is traditionally eliminated in modern radars based on the coherent addition of received signals [3, 4]. In this case, coherent addition (accumulation) of useful signals and the accompanying automatic increase in range resolution in range are proposed to be carried out by the method of performing the inverse fast Fourier transform (FFT) with a fraction of the received realizations reflected from the aircraft within each sequence of the SPNC. Rearrangement of the signals in the order of a monotonic increase in the carrier frequency (within the SPNCH stack with a random law of variation of the carrier frequency) makes it possible to form in the RAM the frequency response of the aircraft, i.e. the dependence of the magnitude of the amplitude and phase of the reflected signals from changes in frequency. If an object maintains a relative spatial position in the interval of irradiation with its sequence of VLF, then using the inverse FFT method the impulse response of the aircraft can be obtained from the vector of the frequency response as the dependence of its reflective properties on the change in the contact time of a radar signal of ultrashort duration (of the order of nanoseconds) of constant amplitude with surface elements LA [5]. The impulse response of the aircraft, taking into account the speed of wave distribution (speed of light s), can be converted into a long-range portrait of the object, i.e. the dependence of the reflective properties of the object on the coordinate of the radial range (along the line of sight). If the position of the aircraft remains unchanged during the T _last in the long-range portrait (DL), coherent summation of the reflections at different frequencies is ensured and the resulting signal-to-noise ratio increases. That is, to ensure noise immunity, it is advisable to extract information about the angular velocity of rotation $$\dot{\gamma }$$

after receiving DLP LA.

To eliminate the phase shifts associated with the radial movement of the aircraft, a recursive algorithm can be used to subtract the phase component from the phase of the received signal, caused solely by a change in the distance to the aircraft. Recurrence is needed when using the wobble pulse repetition rate. If the repetition period is constant, then compensation can be carried out according to the universal formula given in [6-8]. However, both of these approaches require knowledge of the radial speed of the aircraft, calculated at the preliminary stage by the standard method in the single-frequency sounding mode [7].

In this case, the use of radiation of single-frequency signals is proposed to be excluded from considerations of increasing the noise immunity of the tracking mode. Therefore, to eliminate phase raids of a radial nature, in this case, it is appropriate to use the method described in [8, 9]. This method of constructing an informative long-range portrait and estimating the radial speed of the aircraft itself is based on the compensation of the considered phase shifts due to its radial movement. Since this method is described in sufficient detail in [9], there is no need to expound its essence in detail. It is proposed in the framework of this invention to consider the application of the method [9] appropriate, effective, proven and call it a method of compensating for "range" phase incursions (that is, associated with a change in range to the aircraft) by the minimum entropy method.

The third negative factor associated with the manifestation of the turboprop effect (TVE) is eliminated through the use of the proposed method for changing the sounding frequency within each sequence of the SPS according to a random law. A random change in the frequency of the probing signals in packs violates the regular nature of the manifestation of turboprop modulation in the reflection parameters and, as a result, leads to the “smearing” of potential false turboprop components in the structure of the formed long-range portraits.

факторов предлагается осуществлять на основе:Thus, eliminating the negative to identify the law $$F\left[\dot{\gamma }\left(t\right)\right]$$

factors it is proposed to implement on the basis of:

1) the application of the random law of adjustment in the SPCH packets;

2) coherent addition of reflections from aircraft structural elements by the inverse FFT method with its frequency response;

3) the elimination of long-range phase incursions during the formation of the object's DLP by the minimum entropy method in accordance with the method [9].

предлагается формировать и использовать траекторную характеристику ЛА. Траекторная характеристика (ТХ) - это зависимость, показывающая изменение суммы разностей комплексных амплитуд смежных дальностных портретов от номера портрета, т.е. от времени приема очередной пачки СПНЧ.To identify (highlight) the law of change in angular velocity $$\dot{\gamma }$$

It is proposed to form and use the trajectory characteristic of the aircraft. The trajectory characteristic (TX) is a dependence showing the change in the sum of the differences in the complex amplitudes of adjacent range portraits from the portrait number, i.e. from the time of receiving the next pack of SPCh.

It is proposed that the formation of the aircraft DLP preceding the construction of the trajectory characteristic be performed after radiation and reception of SPCH packets reflected from the aircraft. In emitted bursts, the used frequencies of the probing signals must obey a random law that does not repeat from burst to burst. Moreover, in this case, the signals at a frequency f ₀ are no exception.

With a linear change in the carrier frequency in the SPSF packet, the frequency of the first pulse (first frequency) is f ₁ = f ₀ , the frequency of the second pulse (second frequency) is f ₂ = f ₀ + Δf, the frequency of the third pulse (third frequency) is f ₃ = f ₀ + 2Δf and so on, so that the frequency of the Kth pulse (Kth frequency) is f _K = f ₀ + (K-1) Δf, where Δf is the tuning step (interval of change) of the frequency between pulses adjacent by number. If all K frequencies are a priori known, then it is possible to arrange the pulses of different frequencies in a packet randomly, according to a random law, and the law must necessarily change from packet to packet [1].

The duration of the packets T _last should not exceed 5 ms. In this case, the movement of the aircraft in the emission interval of all burst pulses can be neglected. The value of 5 ms is usually called the interval of true coherence, i.e. the interval at which the reflected signals received from the object are coherent due to the immobility of the object.

аналогично [1], а затем формируют в ОЗУ РЛС вектор-столбец зарегистрированных данных, обеспечивая их последовательное расположение в этом m-м векторе-столбце в порядке монотонного возрастания частоты от f₀ до (f₀+F_пер). Из M столбцов (M>>2^2N) формируют избыточную ММСР (ИММСР), располагая столбцы в порядке приема отражений по времени. В результате получают ИММСР, изображенную на фиг.1.After receiving each m-th packet of the LPS from the amplitude A _k and phase φ _{k of the} k-th reflected pulse, the complex value of this reflected signal is formed $${\dot{A}}_k=A_k{e}^{j{\varphi }_k}$$

similar to [1], and then form in the radar RAM a vector column of recorded data, ensuring their sequential location in this m-th vector column in the order of a monotonic increase in frequency from f ₀ to (f ₀ + F _per ). From M columns (M >> 2 ^2N ) form the excess MSSR (IMMSR), arranging the columns in the order of receiving reflections in time. The result is IMMSR, depicted in figure 1.

объекта можно представить массивом (матрицей) комплексных данных $${\dot{H}}_m=\Vert {\dot{H}}_{1m}{\dot{H}}_{2m}{\dot{H}}_{3m}\dots {\dot{H}}_{Km}\Vert$$

.In order to reduce the influence of harmful noise and eliminate phase distortions associated with the radial motion of the aircraft, an inverse FFT operation is performed with each column vector of the IMMSR in combination with the compensation of "long-range" phase incursions by the entropy minimum method [9]. Due to the coherent summation of the reflections at different frequencies, the resulting signal-to-noise ratio is increased and the aircraft DLP is formed, corresponding to the variant of a hypothetical stopping of the aircraft in space, in other words, the variant of the absence of radial movement of the aircraft. Formed in the mth column of DLP $${\dot{H}}_m$$

an object can be represented as an array (matrix) of complex data $${\dot{H}}_m=\Vert {\dot{H}}_{\mathrm{one}m}{\dot{H}}_{2m}{\dot{H}}_{3m}...{\dot{H}}_{Km}\Vert$$

.

можно представить в виде объединения комплексных данных отражений от ЛА по K строкам и M столбцамFrom the vectors of the long-range portraits of the aircraft in the radar RAM, a two-dimensional excess long-range time-scattering matrix (IDMR) is formed, replacing in the IMMSR each m-th column of reflections at different frequencies with the corresponding m-th vector of the long-range portrait. Analytically IDMR $${\dot{H}}_{\mathrm{and}}$$

can be represented as a combination of complex data of reflections from aircraft along K rows and M columns

$${\dot{H}}_{\mathrm{and}}={\displaystyle \underset{m=\mathrm{one}}{\overset{M}{\cup }}{\displaystyle \underset{k=\mathrm{one}}{\overset{K}{\cup }}{\dot{H}}_{km}={\displaystyle \underset{m=\mathrm{one}}{\overset{M}{\cup }}{\displaystyle \underset{k=\mathrm{one}}{\overset{K}{\cup }}{H}_{km}\exp \left(j{\xi }_{km}\right)},\left(\text{one}\right)}}}$$

where H _m is the amplitude of the impulse response in the m-th range portrait in the k-th range resolution element [5-7], ξ _km is the phase of the impulse response in the m-th range portrait in the k-th range resolution element obtained after conducting an inverse FFT with a vector of reflections from the airborne object of the m-th packet of SPCH.

амплитуды реальных отражений будут присутствовать лишь в том случае, если в k-м элементе дальности просматриваемого по радиальной координате окна будет расположен рассеивающий центр (РЦ) поверхности ЛА. Таких РЦ на планере ЛА конечное число. Поэтому многие элементы ИДВМР будут содержать только шумовые составляющие, не несущие полезной информации. Для исключения этих строк из дальнейших операций определяется пороговый уровень Н_п, рассчитываемый по формулеIn the k-th line of IDMR $${\dot{H}}_{\mathrm{and}}$$

the amplitudes of real reflections will be present only if the scattering center (RC) of the aircraft’s surface is located in the kth element of the range viewed along the radial coordinate of the window. There are a finite number of such RCs on an airframe. Therefore, many elements of IDMR will contain only noise components that do not carry useful information. To exclude these lines from further operations, a threshold level H _p is calculated, calculated by the formula

$$H_P=\frac{\mathrm{one}}{KM}{\displaystyle \sum _{m=\mathrm{one}}^M{\displaystyle \sum _{k=\mathrm{one}}^K\left|{\dot{H}}_{km}\right|}}.\left(\text{2}\right)$$

, $$\left|{\dot{H}}_{21}\right|$$

, $$\left|{\dot{H}}_{31}\right|$$

, …, $$\left|{\dot{H}}_{K1}\right|$$

с порогом H_п определяются номера строк ИДВМР, которые (строки) впоследствии будут использованы в способе выявления закона $$F\left[\dot{\gamma }\left(t\right)\right]$$

. Критерием использования k-й строки в дальнейших операциях является выполнение условияIn the first long-range portrait of the aircraft by comparing the modules of its elements $$\left|{\dot{H}}_{\mathrm{eleven}}\right|$$

, $$\left|{\dot{H}}_{21}\right|$$

, $$\left|{\dot{H}}_{31}\right|$$

, ..., $$\left|{\dot{H}}_{K\mathrm{one}}\right|$$

with a threshold H _p , the IDMR line numbers are determined, which (lines) will subsequently be used in the method of revealing the law $$F\left[\dot{\gamma }\left(t\right)\right]$$

. The criterion for using the kth row in further operations is the fulfillment of the condition

$$\left|{\dot{H}}_{k\mathrm{one}}\right|>H_P.\left(\text{3}\right)$$

все k-е строки, не соответствующие критерию (3), обнуляются, что аналогично исключению их из дальнейшего рассмотрения.In IDMR $${\dot{H}}_{\mathrm{and}}$$

all kth rows that do not meet criterion (3) are reset to zero, which is similar to excluding them from further consideration.

является построение ТХ объекта. Для получения величины m-го значения ТХ предлагается использовать выражениеThe next (main) step in identifying the law $$F\left[\dot{\gamma }\left(t\right)\right]$$

is the construction of the TX object. To obtain the value of the m-th value of TX, it is proposed to use the expression

$$\begin{array}{l}{u}_m=\frac{\mathrm{one}}{K}{\displaystyle \sum _{k=\mathrm{one}}^K\{\left[\left|{\dot{H}}_{km}\right|\cos {\xi }_{km}-\left|{\dot{H}}_{k\left(m+\mathrm{one}\right)}\right|\cos {\xi }_{k\left(m+\mathrm{one}\right)}\right]}+\\ +\left[\left|{\dot{H}}_{km}\right|\sin {\xi }_{km}-\left|{\dot{H}}_{k\left(m+\mathrm{one}\right)}\right|\sin {\xi }_{k\left(m+\mathrm{one}\right)}\right]\},\left(\text{four}\right)\end{array}$$

и $$\left|{\dot{H}}_{km}\right|\sin {\xi }_{km}$$

- соответственно косинусная $$\left(R_{km}^{\cos }\right)$$

и синусная $$\left(I_{km}^{\sin }\right)$$

квадратурные составляющие k-го элемента разрешения по дальности в m-м ДлП; $$m=\overline{\mathrm{1,}\left(M-1\right)}$$

- порядковый номер ДлП или вектора-столбца в ИДВМР.Where $$\left|{\dot{H}}_{km}\right|\cos {\xi }_{km}$$

and $$\left|{\dot{H}}_{km}\right|\sin {\xi }_{km}$$

- respectively cosine $$\left(R_{km}^{\cos }\right)$$

and sinus $$\left(I_{km}^{\sin }\right)$$

quadrature components of the k-th element of range resolution in m-m DlP; $$m=\overline{\mathrm{one,}\left(M-\mathrm{one}\right)}$$

- serial number of DlP or column vector in IDMR.

Thus, the difference value between the cosine components of adjacent range portraits and the sine components of adjacent DLPs, averaged over all significant informative range elements, is calculated, in this case the mth and (m + 1) -th DLPs are considered adjacent.

Of the m-x values calculated using formula (4), the full TX aircraft is formed, including (M-1) elements.

.A graphical interpretation of the trajectory characteristics of the aircraft, obtained by mathematical modeling, is presented in figure 2. The dotted line in figure 2 denotes the true law of change in the angular velocity (ZIUS) of an aircraft located at a distance of 30 km, an altitude of 1 km, moving at a speed of 100 m / s at a heading angle of 30 ° with yaw of a glider with an amplitude of 2 ° and an average angular velocity of yaw $$\dot{\gamma }=\mathrm{1,5}°/c$$

.

As can be seen from figure 2, the ruggedness of the originally formed TX is too strong, which does not allow for its automated analysis. To smooth TX, it is proposed to use the moving average method based on calculations of each m-th smoothed TX value according to the formula

$$u_{\mathrm{from}glm}=\frac{\mathrm{one}}{M_{h\mathrm{at}}}{\displaystyle \sum _{s=\mathrm{one}}^{M_{h\mathrm{at}}}{u}_{m+s-M_{h\mathrm{at}}/2}},\left(\text{5}\right)$$

where the number of samples M _{hv of the} private sample extracted from the general sample is determined by the formula

$$M_{h\mathrm{at}}=\frac{T_{TH\min }}{5T_{P\mathrm{about}\mathrm{from}l}},\left(\text{6}\right)$$

based on the fact that the time of sampling in a private sample should not exceed a quarter of the minimum period T _{TH min of} yaw during trajectory instabilities of the flight of an aircraft in a turbulent atmosphere, and also because the readings in the TX follow after a period of time equal to the duration of the SPS packet T _last . In this case, it is proposed to use a fifth of the minimum glider yaw period T _{TH min} , which is about 1 s.

To create a better, smoother, smoother TX more smooth, suitable for automated analysis, it is proposed to repeat the process of smoothing the original TX of an air object 5 times.

, M_p=M-M_чв/2-1 - рабочая длина сглаженной ТХ в пикселях (элементах, точках).A graphical view of the smoothed path characteristic corresponding to the original TX (Fig. 2) is shown in Fig. 3. As you can see, this TX is quite suitable for determining intervals with maximum, minimum and average angular velocity of rotation of the aircraft relative to the line of sight. Analytically smoothed TX can be expressed by combining its elements $$Z\left(m\right)={\displaystyle \underset{m=\mathrm{one}}{\overset{M_p}{\cup }}{u}_{\mathrm{from}glm}}$$

, M _p = MM _CV / 2-1 - the working length of the smoothed TX in pixels (elements, points).

изменения угловой скорости поворота ЛА во времени предлагается использовать правило: более высокому значению ТХ соответствует более высокая угловая скорость поворота ЛА при ТН, и наоборот. Таким образом, поведение сформированной ТХ предлагается (что целесообразно) считать косвенным законом изменения угловой скорости $$\dot{\gamma }$$

поворота ЛА с течением времени $$F\left[\dot{\gamma }\left(t\right)\right]$$

, выявление которого и является задачей изобретения. Иными словами сформированную сглаженную ТХ воздушного объекта Z(m) предлагается использовать в качестве закона $$F\left[\dot{\gamma }\left(t\right)\right]$$

его поворота относительно линии визирования (относительно РЛС). При этом следует учитывать тот факт, что время излучения T_{изл m} m-й последовательности сигналов с перестройкой несущей частоты связано с соответствующим номером u_{сгл m} сглаженной траекторной характеристики воздушного объекта следующим выражением T_{изл m}≈T_посл(m+М_чв/2).To identify the law $$F\left[\dot{\gamma }\left(t\right)\right]$$

It is proposed to use the rule of changing the angular velocity of rotation of an aircraft in time: a higher value of TX corresponds to a higher angular velocity of rotation of an aircraft at VT, and vice versa. Thus, the behavior of the formed TX is proposed (which is advisable) to be considered an indirect law of change in angular velocity $$\dot{\gamma }$$

turning aircraft over time $$F\left[\dot{\gamma }\left(t\right)\right]$$

, the identification of which is the object of the invention. In other words, it is proposed to use the generated smoothed TX of the airborne object Z (m) as a law $$F\left[\dot{\gamma }\left(t\right)\right]$$

its rotation relative to the line of sight (relative to the radar). In this case, one should take into account the fact that the radiation time T _{rad m of the} mth sequence of signals with tuning of the carrier frequency is associated with the corresponding number u _{sm m of the} smoothed path characteristic of an air object by the following expression T rad _m ≈T _last (m + M _FW / 2) .

The proposed method is more efficient compared to the prototype [1], since it does not require more frequent emission of signals at the fundamental frequency f ₀ , and also analyzes information about the accompanied HE only after coherent summation of the signals in the DL, i.e. less sensitive to interference and noise of the receiver. The method is recommended for use in radar classification systems VO, requiring averaging of the signs of classification by angle, as well as in the formation of radar data in order to determine the most informative intervals of inverse synthesis.

Information sources

1. RF patent No. 2234110. A method of constructing a two-dimensional radar image of an air target. Mitrofanov D.G., Bortovik V.V. and other Application No. 2003100255. BIPM No. 22 dated 08/10/2004. S.546-548 (prototype).

2. Mitrofanov D.G., Prokhorkin A.G., Nefedov S.I. Measurement of the transverse dimensions of aircraft by the frequency extent of the Doppler portrait // Radio Engineering. 2008 No. 1. S.84-90.

3. Theoretical Foundations of Radar / Ed. POISON. Shirman. - M .: Owls. Radio, 1970 .-- 560 p.

4. Finkelstein M.I. Basics of radar. Textbook for high schools. - M .: Owls. Radio, 1973.- 496 p.

5. Mitrofanov D.G. Formation of a two-dimensional radar image of a target with trajectory flight instabilities // Radio engineering and electronics. RAS, 2002. No. 7. S.852-859.

6. Mitrofanov D.G. A complex adaptive method for constructing radar images in dual-purpose control systems // Theory and Control Systems. Proceedings of the RAS. 2006. No. 1-2. S.101-118.

7. Mitrofanov D.G. The method of constructing radar images of aerodynamic aircraft // Flight. 2006. No. 11. S 52-60.

8. Mayorov D.A., Savostyanov V.Yu., Mitrofanov D.G. Measurement of the radial speed of airborne objects in the frequency tuning mode // Measuring technique. 2008. No2. C 43-47.

9. Patent No. 2226402 dated 06/10/2008. A method of measuring the radial speed of an air target in the frequency tuning mode from pulse to pulse. Savostyanov V.Yu., Mayorov D.A., Prokhorkin A.G., Mitrofanov D.G. Publ. 06/10/2008. BIPM No. 16. Part III. S.752.

Claims (1)

A radar method for detecting the law of change in the angular velocity of rotation of an airborne vehicle being followed by successively received signal reflections with carrier frequency tuning, which means that sequences of signals with carrier frequency tuning of 2 ^N pulses (N = 8.9) each are emitted in the direction of the airborne object the frequency of these pulses varies from pulse to pulse in the range from f ₀ to (f ₀ + F _per ), where f ₀ is the initial carrier frequency of the quasi-optical reflection region of the centimeter range, F _per is the range the azone, in which the frequency is tuned from pulse to pulse with an interval Δf = F _lane / (2 ^N -1), receive signals reflected from the airborne object, along the received reflected signals they accompany the airborne object in angular coordinates and range, are recorded in random access memory amplitudes and phases, as well as the number and time of reception of reflected signals with tuning of the carrier frequency, and these data are recorded on a time interval T ₃ , an order of magnitude greater than 2 ^2N T _and , where T _and is the pulse repetition period, and the teaching of each sequence of signals with the tuning of the carrier frequency of 2 ^N pulses is carried out during the time interval T _last not exceeding 5 ms, i.e. over a period of time, an order of magnitude shorter than the correlation interval of the trajectory instabilities of the flight of an air object, while the pulse frequency of each signal sequence with the tuning of the carrier frequency of 2 ^N pulses is changed based on the condition that within each 2 ^N- pulse sequence the frequency of each pulse is repeated only once, after receiving, converting from analog to digital and writing to the random-access memory, the parameters of the reflected signals are formed a rectangular two-dimensional data array called a multi-frequency synthesized scattering matrix, for which, within each sequence of signals with carrier frequency tuning, the registered data are rearranged in the random access memory, providing their sequential arrangement in the columns of the multi-frequency synthesized scattering matrix in the order of a monotonic increase in frequency from f ₀ to (f ₀ + F _lane) to yield a two-dimensional array of data columns whose p found on the rear according to the numbers of emitted and correspondingly received sequences with the rearrangement of carrier signals, and the data in the columns are arranged in the order of monotonous change the emission frequency of f ₀ to (f ₀ + F _lane) thus in each row of the array have phase and amplitude the reflected signals of the same frequency, the data on the parameters of the reflected signals are recorded in the matrix elements of the multi-frequency synthesized scattering in a complex form, namely, after receiving each m-th packet of signals from tuning th carrier frequency from the amplitude A _k and phase φ _k k-th echo pulse is formed for recording a complex value of the reflected pulse as

,
characterized in that when forming a multi-frequency synthesized scattering matrix, the number M of columns in it is used, subject to the inequality M >> 2 ^2N , and the number of rows K is left equal to K = 2 ^N , the multi-frequency synthesized scattering matrix formed under such conditions is called the excess multi-frequency matrix synthesized scattering, each element of the formed excess matrix of multi-frequency synthesized scattering is assigned indices k and m, where k is the row number, am is the column number of the excess matrix of the multi-frequency synthesized scattering, so the complex value of the reflected signal in the mth column of the kth row of the excess matrix of multi-frequency synthesized scattering is denoted

, where A _km and φ _km are, respectively, the amplitude and phase of the reflected signal received in the mth sequence of signals with tuning of the carrier frequency at the kth frequency, after rearranging the data in each mth column in the order of a monotonous increase in the carrier frequency is carried out with a vector the complex data of this column of the excess matrix of multi-frequency synthesized scattering the inverse fast Fourier transform operation in combination with the compensation of long-range phase incursions by the minimum entropy method, as a result of each m-th column from ytochnoy matrix of multi-frequency-synthesized dispersion obtained m-th vector of complex numbers

, called in other words the m-th range portrait of an air object or the vector of the m-th range portrait, from the vectors of the obtained range portraits, in order of increasing numbers, an excess long-range scattering matrix with M columns and K rows is formed, having an analytical record of the form

,
where H _km is the amplitude of the impulse response in the m-th range portrait in the k-th range resolution element, ξ _km is the phase of the impulse response in the m-th range portrait in the k-th range resolution element obtained after performing the inverse fast Fourier transform with the vector of reflections from the airborne object of the mth packet of signals with tuning of the carrier frequency, the threshold level value H _p is determined by finding the average, over the entire excess distance-time scattering matrix, the module element matrix values by the formula

,
comparing the magnitudes of the elements of the first column of the excess long-range time-scattering matrix with the value of H _p and if the condition

the elements of the kth row of the excess long-range time-scattering matrix are left unchanged; otherwise, all the elements of the kth row of this matrix are reset to zero, form the trajectory characteristic of the air object as a dependence showing the change in the sum of the differences of the complex amplitudes of adjacent range portraits in accordance with the change range portrait numbers, for this, the mth value of the trajectory characteristic of the air object is calculated according to the formula

Where

and

- respectively cosine

and sinus

quadrature components of the k-th range resolution element in the m-th range portrait,

- the serial number of the range portrait or column vector in the excess long-range time-scattering matrix, five times in a row carry out the procedure of smoothing the trajectory characteristics of an air object, for which the number of elements _{Mf of a} private sample representing consecutive elements of the trajectory characteristics of an air object is preliminarily determined by the formula

, where T _THmin is the minimum period of yaw of the airborne glider during trajectory flight instabilities in a turbulent atmosphere, amounting to about 1 s, and then the mth value of the smoothed trajectory characteristic of the airborne object is determined by the formula

,
the fivefold smoothed trajectory characteristic of an air object is used as a law of change in the angular velocity of rotation of the followed air object over time, taking into account the fact that the radiation time T _{rad m} mth sequence of signals with tuning of the carrier frequency is associated with the corresponding number u _{sm m} smoothed path characteristic of the air object expression T rad _m ≈ T _last (m + M _FF / 2).

Images