RU2254592C1 - Mode of location target(variants) - Google Patents

Abstract

FIELD: the invention refers to the technique of detection of a target and determination of the direction at a target.

SUBSTANCE: the mode is realized by way of receiving of ultra wideband impulses reflected from the target, of delaying them on various time multitude in various channels of surveillance and multi channel processing. In the first variant of the current mode variation of the form of receiving impulses on a great number of discrete time positions are carried out by way of averaging-out by channels of surveillance at known direction of incoming reflected impulses in a beforehand designed control sector and then found valuation of the form of receiving impulse is used as a base signal in multi channel correlation processing. In the second variant valuation of magnitude of receiving impulse is formed in concrete moment of time for each base direction in beforehand given angular sector of control, valuation of the form of the receiving impulse is found according to formed valuations of magnitude 0f the receiving signal for various discrete moments of time; found valuation of receiving impulse is used as a base signal in multi channel correlation processing; out of multitude of results of correlation processing correlation maximum is chosen. This maximum is used as preliminary threshold decision statistics in the procedure of detection of the target; the direction of incoming reflected impulses with the help of interpolating valuation of the position of the correlation maximum in the environs of that base direction for which the largest result of multi channel correlation processing.

EFFECT: the use of this invention at location of a target with the help of ultra wideband impulses allows to receive signals incoming not only from in advance chosen base directions.

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Description

Field of Invention

The present invention relates to techniques for detecting a target and determining a direction to it. In particular, the present invention relates to variants of a method for locating a target using ultra-wideband pulses, as well as to software products for implementing these methods.

The current level of technology

Recently, there has been an increased interest in the creation of radar systems using ultra-wideband signals, i.e. signals whose band is comparable to the center frequency of the spectrum. It is also relevant to create such systems for sensing the bowels of the earth, sea depths and atmosphere (Issues of promising radar. - M .: Radio Engineering, 2003 (Series Radar). - S.22-25). This is explained by the physical nature of ultra-wideband signals, generating a number of useful properties. For example, when reflecting, ultra-wideband signals become carriers of a sufficiently large amount of information about the probed objects themselves (Borzov AB Analysis of the contributions of individual elements of an object of complex shape to the general scattering field of electromagnetic waves on objects of complex shape. - Electromagnetic waves and electronic systems, 1998, no. 10, p. 38-54). Ultra-wideband signals can hardly be suppressed when passing through a medium with changing permeability properties. In radar, their use opens up the possibility of remote target recognition and overcoming the Stealth anti-radar technology.

However, along with the advantages, the nature of ultra-wideband signals also creates difficulties that impede the use of well-known technical solutions for the implementation of ultra-wideband radar systems. One of the key problems is the task of organizing optimal or suboptimal reception with unpredictable signal distortions. Indeed, in real conditions, the reflective characteristics of objects, and often the properties of the propagation medium, cannot be determined with such a degree of accuracy that at least approximately predict the distortions that occur in the reflected ultra-wideband signals observed at reception. Traditional radar technology assumes complete a priori information about the shape of the reflected signals and, accordingly, the organization of reception using matched filters. It is clear that efficient reception of ultra-wideband signals is possible only in the transition from traditional methods to adaptive processing.

A known location method using ultra-wideband pulses emitted and received by the antenna array, in which the entire strip of ultra-wideband pulses is divided into separate frequency subbands for the convenience of generating angular deviations of the beam using phase shifters (EPO application No. 0618641, publ. 05.10.1994). The disadvantage of this method is the lack of consideration of possible distortion of the shape of the reflected signals.

The closest analogue of the present invention is a method for location of the target, which consists in the fact that: emit ultra-wideband pulses by the array of antenna elements; when receiving reflected pulses in a predetermined angular monitoring sector, the signal received by each antenna element of said array of antenna elements is delayed with the help of series-connected delay elements in each of the plurality of observation channels used; carry out the target detection procedure by using multichannel correlation signal processing at the outputs of the mentioned delay elements in the various mentioned observation channels (US patent No. 6515622, publ. 04.02.2003). The disadvantage of this method is the lack of indication of how to form the reference signals and how to receive signals coming from directions that differ from the selected reference directions.

SUMMARY OF THE INVENTION

The purpose of the present invention is to develop such a method for locating a target that would be free from these drawbacks.

To solve this problem and achieve the specified technical result in the method of target location, which consists in the following: emit ultra-wideband pulses by an array of antenna elements; when receiving reflected pulses in a predetermined angular control sector, the signal received by each antenna element of the array of antenna elements is delayed using series-connected delay elements in each of the plurality of observation channels used; carry out the target detection procedure by using multi-channel correlation signal processing at the outputs of the delay elements in different observation channels, in the first embodiment of the method, when the direction of arrival of the reflected pulses is known, in accordance with the present invention with multi-channel correlation signal processing: the shape of the received pulse is estimated on the set discrete time positions by averaging over the observation channels of the signals on the subsets of the outputs of those of the delay elements which in different observation channels correspond to the same discrete time position with a known direction of arrival of reflected pulses in a predetermined angular control sector; then use the found estimate of the shape of the received pulse as a reference signal in multi-channel correlation processing.

In the second variant of the method, when the direction of arrival of the reflected pulses is unknown, in accordance with the present invention when multi-channel correlation signal processing: form separate estimates of the magnitude of the received pulse at a set of discrete time positions for each reference direction from a pre-selected finite set of reference directions in the angular control sector, moreover, an estimate of the magnitude of the received pulse at discrete moments for each of the reference directions is formed by averaging n about channels for observing signals on subsets of samples that for a given reference direction correspond to the same discrete time position; find an estimate of the shape of the received pulse according to the formed estimates of the magnitude of the received pulse at various discrete time instants; using the found estimate of the shape of the received pulse as a reference signal in multi-channel correlation processing; on the set of results of multichannel correlation processing, a correlation maximum is selected, which is used as a threshold threshold statistics in the target detection procedure; estimate the direction of arrival of the reflected pulses in a predetermined angular control sector using an interpolation estimate of the position of the correlation maximum in the vicinity of that reference direction from the selected set of reference directions for which the greatest result of multichannel correlation processing is obtained.

Moreover, the formation of multiple samples in each of the observation channels can be carried out using linear interpolation due to the fact that they find the weights of linear signal combinations at the outputs of the delay elements in different observation channels and use these found weights of linear signal combinations to form conditional estimates of the shape of the received pulses on a given set of discrete time positions consistent with one of the selected set of reference directions.

The same task with the achievement of the same technical result is solved by means of software products, each of which, when executed on a computer, provides the implementation of the aforementioned multi-channel correlation signal processing in one of the above methods.

In the current level of technology, no sources of information have been identified that would contain information about objects of the same purpose with the indicated set of distinctive features, which allows us to consider the method of the present invention new and having an inventive step.

Brief Description of the Drawings

The present invention is illustrated by drawings, in which the same elements in all the drawings are denoted by the same reference position, and where:

Figure 1 is a block diagram of a conventional device for generating probing ultra-wideband pulses and receiving reflected signals;

Figure 2 illustrates the shape of the probe pulse generated by the device of figure 1;

Figure 3 illustrates various types of reflections of the probe pulse of figure 2 from a real object;

Figure 4 is a block diagram of a device for suboptimal detection of reflected ultra-wideband signals coming from known directions, for implementing the method according to the first embodiment of the present invention;

Figure 5 illustrates the case of receiving a reflected ultra-wideband signal from an object, the direction of which is not known in advance;

6 illustrates the implementation of the second variant of the method according to the present invention;

7 is a block diagram of a device for implementing the method according to the second embodiment of the present invention.

Fig. 8a is a block diagram of the device of Fig. 7 in the case of applying general interpolation to restore the samples of the received pulse in intermediate positions.

Fig. 8b is a block diagram of the device of Fig. 7 in the case of linear interpolation to restore the samples of the received pulse in intermediate positions.

Detailed Description of Preferred Embodiments

Typically, an ultra-wideband location system is implemented using a multi-element antenna array, a block diagram of which is shown in figure 1. This multi-element antenna array, in this case, is selected linear (one-dimensional) for ease of explanation. It contains observation channels 1 from the first (1.1) through the Mth (1.M). Each observation channel 1 contains an antenna element 2 connected in series, a controlled delay unit 3, an operation mode switch 4 (receive-transmit switch), a low-pass filter 5 and a delay line 6, which consists of L identical delay elements 7, each with a delay time T , and has L + 1 taps. Blocks 3 controlled delay are used to set the main direction of sounding both in transmission and in reception. Low-pass filters 5 are designed for selection of reflected signals in the frequency range. Delay lines 6 are used to perform optimal observation processing to detect and evaluate the direction of arrival of the reflected pulse.

This invention does not address the issues of the formation and emission of high-power ultra-wideband pulses (considered, for example, in the work of Shirman Y.D. et al. Radar recognition methods and their modeling // Foreign Radio Electronics. Successes in Modern Radio Electronics. 1996, No. 11, p. 3 ) Actually, the shape of the probe pulses turns out to be close to either bell-shaped, as shown in Fig. 2, or the type of cosine on the pedestal. The noted "subtle" differences in the shape of the emitted ultra-wideband pulses can only slightly affect the results of recognition of distant targets, but in no way the results of measuring radar parameters (range to the target and direction to the target). Indeed, upon reflection and when passing through a medium, ultra-wideband pulses are distorted so radically that the differences noted above in the initial form can be completely considered insignificant. The only available restriction that can be guided by when describing reflected pulses under conditions of working with nonrelativistic objects is that their spectrum is within the original sounding frequency range (0-1 GHz), which corresponds to the pulse duration shown in Fig. 2 equal to Δt _and ≈1 ns.

Due to the relatively short duration, the length of the probe pulses in space is usually much smaller than the size of real objects. As a result, a whole group of pulses with a pseudo-random distribution of delays, amplitudes and with various shapes arises during reflection. Figure 3 schematically shows the process of reflection of one probe pulse from an object with an inhomogeneous surface. In order to ensure effective summation of the energy of the reflected signals in an adaptive receiving system built on the basis of the circuit of FIG. 1, the duration of the delay lines (L × 7) should be chosen slightly more (about 2-2.5 times) the maximum allowable “stretching” of the reflected pulses in time.

Figure 1 carry out the following operations:

ultra-wideband pulses are emitted by the antenna elements 2 (switch 4 of the operating mode in the "transmission" position, i.e. down in figure 1);

when receiving reflected pulses (switch 4 of the operating mode in the “receiving” position, i.e., up in FIG. 1), the signal received by each antenna element 2 is delayed using the delay elements 7 connected in series, forming a delay line 6 in each channel 1 observations;

carry out the target detection procedure by using multi-channel correlation signal processing at the outputs of the delay elements 7 in different delay lines 6.

These operations are performed both in the method of the present invention and in the closest analogue.

Let us now consider those operations that distinguish the first variant of the method according to the present invention, i.e. the case of target detection with a precisely known direction of arrival of reflected pulses.

. В силу того, что направление на объект установлено точно, каждая отдельная последовательность

при наличии отраженного импульса содержит аддитивную смесь одного и того же сигнала и шума. При отсутствии отраженного импульса последовательности

содержат независимые шумовые выборки. В математической форме это может быть записано так

при справедливости гипотезы Н₀ (сигнал отсутствует),We denote the sample of samples adopted by the multichannel system by

. Due to the fact that the direction to the object is set accurately, each individual sequence

in the presence of a reflected pulse, it contains an additive mixture of the same signal and noise. In the absence of a reflected pulse sequence

contain independent noise samples. In mathematical form, it can be written like this

with the validity of the hypothesis H ₀ (no signal),

при справедливости гипотезы Н₁, (сигнал присутствует),

if the hypothesis H _{1 is} true, (a signal is present),

- выборка шумовых компонент, распределенных по нормальному закону с нулевым средним и дисперсией σ², наблюдаемых на выходах линий 6 задержки.where S (t) is the reflected ultra-wideband signal of unknown shape, t ₀ is the time instant at which the sample of observations is formed,

- a sample of noise components distributed according to the normal law with a zero mean and variance σ ² observed at the outputs of the delay lines 6.

Let us dwell in more detail on the statistical characteristics of noise, since it is they that are decisive in solving the problem under conditions of a priori uncertainty. Firstly, due to the autonomous operation of the observation channel 1 of the receiving system, the noise components present in them will be statistically independent. Secondly, with the technically optimal organization of delay lines 6 with taps at intervals determined by Kotelnikov's theorem, the noise components of the samples present in one observation channel 1 at different taps will also be statistically independent.

, присутствующей на срезе отводов с одинаковыми индексами задержек i (одинаковые задержки в каналах 1 на i Т), будет следующей:As a result, in the presence of a reflected signal, the conditional probability density of observation of the sample

present on the slice of taps with the same delay indices i (the same delays in channels 1 to i T) will be as follows:

нет никакой априорной информации, их оценку при каждом индексе задержки i можно сформировать только на основе критерия максимального правдоподобияDue to the fact that relative to the signal components

there is no a priori information, their estimation at each delay index i can be formed only on the basis of the maximum likelihood criterion

Solution (2) can be found by differentiation.

In the process of operation of the sensing system with ultra-wideband signals in figure 1, periodic formation and processing of samples

.

.

где m - некоторое целое положительное число, чтобы гарантировать при обработке полное использование энергии отраженных импульсов, имеющих длительность не более

Например, если взять максимальную задержку в линиях (LT) с двойным запасом относительно допустимых длительностей отраженных импульсов, то верхней границей необходимого периода повторения будет

что совпадает с верхней границей длительности принимаемых сверхширокополосных импульсов.The sampling recurrence interval shall not exceed

where m is some positive integer in order to guarantee during processing the full use of the energy of reflected pulses having a duration of not more than

For example, if we take the maximum delay in lines (LT) with a double margin relative to the allowable durations of reflected pulses, then the upper limit of the required repetition period will be

which coincides with the upper limit of the duration of the received ultra-wideband pulses.

.Relation (3) determines the estimate of the maximum likelihood of a received signal for each periodically generated sample

.

Assuming that the reflected signal has a shape exactly matching (3), a suboptimal detection procedure can be organized. Indeed, if the form S (t) of the received signal is known, then the detector, optimal in the sense of the Neumann-Pearson criterion, should have the form:

Where

is the logarithm of the likelihood ratio calculated up to factors independent of the observations, P is the threshold set by the noise level and providing a given probability of false detection.

Substituting the maximum likelihood estimate (3) in (5), we obtain the desired detection rule:

If threshold P is exceeded, a decision should be made on the presence of a signal. This rule for the detection of reflected ultrawideband signals arriving from a known direction corresponds to a system whose block diagram of the antenna array is shown in FIG. 4. Compared with the circuit of FIG. 1, adders 8 are added to this system for summing signals from the same taps of delay lines 7 in different observation channels 1, squaring units 9 to obtain the second degree of signals summed on each adder 8, a common adder 10 for summing the values obtained in blocks 9 and a decision block 11 for comparing the total amount from the total adder 10 with a threshold P and making an appropriate decision on the presence or absence of a reflected signal from this direction.

In this case, it is easy to verify that the shape of the received pulse is estimated at a set of discrete time positions by averaging over the channels 1 for observing the signals on the subsets of the outputs of those delay elements 7 that correspond to the same discrete time position in different observation channels 1 with a known direction the arrival of reflected pulses; and using the found estimate of the shape of the received pulse as a reference signal in said multi-channel correlation processing.

в точном соответствии с направлением прихода отраженных импульсов (т.е. с направлением на контролируемый объект). Однако на практике такая ситуация встречается достаточно редко. Наиболее характерными являются ситуации со случайным расположением контролируемых объектов в пределах некоторого углового сектора. При этом возникает задача обнаружения отраженных сигналов с одновременной оценкой направления их прихода. Далее ограничимся рассмотрением случаев при расположении зондируемых объектов на плоскости. Пространственная задача принципиально не отличается от задачи на плоскости, только требует более сложной модели для описания преобразований сигналов в антенной решетке. Кроме того, для упрощения выводов будем ориентироваться на линейную эквидистантную антенную решетку с разнесением чувствительных элементов на расстояние d.The detection rule (6) and the resulting detector structure in Fig. 4 are obtained under the assumption that the shape of the useful components in the observation channels 1 coincides. This is only possible when setting delays.

in exact accordance with the direction of arrival of the reflected pulses (i.e., with the direction to the controlled object). However, in practice this situation is quite rare. The most characteristic are situations with a random arrangement of controlled objects within a certain angular sector. This raises the problem of detecting reflected signals with a simultaneous assessment of the direction of their arrival. Further, we restrict ourselves to the consideration of cases when the probed objects are located on a plane. The spatial problem does not fundamentally differ from the problem on the plane, it only requires a more complex model to describe the signal transformations in the antenna array. In addition, to simplify the conclusions, we will focus on a linear equidistant antenna array with a spacing of the sensitive elements at a distance d.

Figure 5 shows the situation of reception of the reflected ultra-wideband signal from an object located in some unknown direction, characterized by an angle α counted from the direction of radiation of the probe pulse. In Fig. 5, each observation channel 1 is connected to a device 12 for detecting and estimating the direction of arrival of reflected pulses, the structure of which will be obtained as a result of the following analysis.

, где k₀ - угол, задающий направление излучения зондирующих импульсов, отсчитываемый от нормали к антенной решетке. В случае линейной эквидистантной антенной решетки с разнесением элементов 2 на расстояние d каждому из таких направлений соответствует собственное множество

компенсирующих задержек в каналах 1 наблюдений. То есть, к задержкам, согласованным с выбранным направлением зондирования α₀, требуются дополнительные поправкиSince it is technically impossible to implement the reception from the continuum of directions, the only possible way is to use a finite set of controlled directions with

, where k ₀ is the angle defining the direction of radiation of the probe pulses counted from the normal to the antenna array. In the case of a linear equidistant antenna array with elements 2 spaced apart by a distance d, each of these directions corresponds to its own set

compensating delays in channels 1 observations. That is, to the delays consistent with the chosen sounding direction α ₀ , additional corrections are required

Additional delays (7) can be realized either using special blocks, or based on the corresponding linear transformations of the samples in the observation channels 1. The second of these methods does not require the use of an individual set of delay lines for each controlled direction. But the first method allows us to synthesize the desired joint algorithm in a simpler and more visual form. Therefore, we will focus on the first method below. The final results will be the same in both cases.

нужно сформировать оценку максимального правдоподобия (ОМП). Поскольку в общем случае истинное направление не будет совпадать ни с одним из контрольных, для расчета потребуются интерполяционные методы. В классической теории оценивания параметров сигналов такая задача хорошо изучена. Общепризнанным является то, что приближенная оценка максимального правдоподобия может быть получена на основе разложения в ряд Тейлора по оцениваемому параметру отношения правдоподобия с точностью до членов второго (или более высокого) порядка. В рассматриваемой задаче воспользоваться указанным приближением возможно, если угловое разнесение контрольных направлений Δα не будет приводить к относительным задержкам на крайних элементах 7 задержки, большим длительности Δt_и излучаемого импульса (см. фиг.2). Пояснить сформулированное требование поможет фиг.6, на которой показаны задержанные в каналах 1 наблюдения элементарные отраженные импульсы в случае двух соседних контрольных направлений.According to the general conclusions of the statistical theory of detection, which are also valid for the problem under consideration, under conditions of parametric a priori uncertainty, the method of correlation reception using a reference copy is asymptotically optimal, in which the unknown signal parameters are replaced by maximum likelihood estimates. In our case, the parameter α determining the direction of arrival is unknown. For him, on the basis of the corresponding processing of observations obtained for many control directions,

you need to form an estimate of maximum likelihood (WMD). Since in the general case the true direction will not coincide with any of the control ones, interpolation methods will be required for the calculation. In the classical theory of estimating signal parameters, such a problem is well studied. It is generally recognized that an approximate estimate of maximum likelihood can be obtained by expanding into a Taylor series in the estimated parameter of the likelihood ratio up to terms of the second (or higher) order. In the considered problem, it is possible to use this approximation if the angular spacing of the control directions Δα does not lead to relative delays at the extreme delay elements 7, longer than Δt _{and the} emitted pulse (see Fig. 2). Fig. 6, which shows the elementary reflected pulses delayed in the observation channels 1 in the case of two adjacent control directions, will help to clarify the formulated requirement.

The analytical formula for the relative delay that occurs at the extreme elements 7 of the delay for adjacent control directions with indices k and k + 1, has the form:

As can be seen from the last formula, the largest relative delay at the extreme delay elements 7 occurs in the case of sounding along the normal to the antenna array α ₀ = 0. In this case

получаем для шага сетки контрольных направлений следующее условие:Based on the fact that

we obtain the following condition for the step of the grid of control directions:

Taking into account that, from the point of view of technical requirements, the greatest step in the grid of control directions is the best, from (8) we find the rule for calculating the optimal Δα:

предполагает, что периодически формируются наборы, состоящие из 2k₀+1 выборок

Using a finite set of control directions

assumes that sets consisting of 2k ₀ +1 samples are periodically formed

Each of the samples in the specified set corresponds to the control direction with the same index value k. It is more convenient to present the corresponding sample of observations for each control direction in the form of a matrix of size M ^* (L + 1)

For each control direction, in accordance with (3), a conditional estimate of the maximum likelihood of the received signal can be generated

obtained as a result of averaging observations over the columns of matrix (10). Since the control directions, in the general case, do not coincide with the true direction of the return channel, estimates of the maximum likelihood of signals (11) cannot be considered correct. For such estimates, the name of generalized maximum likelihood estimates (OOMP) is proposed (see the work of A. Trifonov, Yu.S. Shinakov. Joint distinguishing of signals and estimation of their parameters against the background of interference. - M .: Radio and communication, 1986). Nevertheless, the indicated OMP of the received signals can be used to calculate the conditional probability densities and the formation of the direction of arrival of the reflected signal by the OMP. According to the adopted model (1), the conditional probability density of observation of the sample x (α _k ) for each controlled direction will be

Substituting (11) into (12), we obtain

Where

variance estimate based on a sample formed from the ith column of the observation matrix X (α _k ). Using (13), (14), after simple transformations, we can obtain a second-order interpolation relation for calculating the OMP of the arrival direction of the reflected signal

- оценка контрольного направления, для которого достигается наибольшее значение условной вероятности (13) (грубая оценка направления прихода отраженного сигнала);Where

- assessment of the control direction, for which the greatest value of the conditional probability is achieved (13) (a rough estimate of the direction of arrival of the reflected signal);

индексы, связанные с контрольными направлениями, соседними с

- значения статистик (16), рассчитанные для контрольных направлений

.- logarithms of conditional probability densities (13) calculated up to components independent of observations;

indices associated with control directions adjacent to

- statistics values (16) calculated for control directions

.

будет иметь минимумIn the position of assessing the maximum likelihood of the direction of arrival of the reflected signal (15), statistics

will have a minimum

через выборки наблюдений

. Вместо этого снова можно воспользоваться интерполяционными соотношениями. Указанный подход приводит к следующему соотношению для предпороговой статистики:In order to generate pre-threshold statistics of the decision rule similar to (6), in the case of using the directional direction of arrival of the reflected signal by OMP (15), it is not necessary to refer to the calculation

through observation samples

. Instead, interpolation relationships can again be used. The indicated approach leads to the following relation for prethreshold statistics:

conditional logarithms of likelihood relations formed under the assumption that the reflected signal comes from the kth control direction.

In accordance with (19), the asymptotically optimal, in the sense of the Neumann-Pearson criterion, rule for detecting the reflected signal has the following form:

where P is the threshold for deciding on the presence of a signal, calculated from the acceptable level of false alarms.

каждого из которых i относится к номеру антенного элемента (i=1,..., M), j относится к отводу от выхода соответствующего элемента задержки (j=0, 1,..., L), к которому подключен вход данного весового элемента, а индексом k отмечен номер опорного направления (k=0, ±1, ±2,..., ±k₀). Остальные блоки имеют те же обозначения и выполняют те же функции, что и на фиг.4. Приведенная на фиг.7 блок-схема обеспечивает обнаружение цели с одного из выбранных опорных направлений. Для всех

опорных направлений эту блок-схему нужно повторить n раз, чтобы получить как бы n «слоев» изображенной на фиг.7 матрицы.Relations (15), (16) and (18) - (20) determine the structure of the blocks for estimating the direction of arrival and the detector of the reflected ultra-wideband signal in the desired joint algorithm. In Fig.7 presents a block diagram of a system for detecting and determining the direction to the target (see Fig.4) for the case when this direction is not known in advance. In this block diagram, the triangles indicate the first - Mth antenna elements, the chains of rectangles represent the delay lines from the first - Lth delay elements, and the circles indicate the weight elements, in weight

each of which i refers to the number of the antenna element (i = 1, ..., M), j refers to the tap from the output of the corresponding delay element (j = 0, 1, ..., L) to which the input of the given weight element, and the index k marks the number of the reference direction (k = 0, ± 1, ± 2, ..., ± k ₀ ). The remaining blocks have the same designations and perform the same functions as in figure 4. The block diagram shown in FIG. 7 provides target detection from one of the selected reference directions. For all

of reference directions, this flowchart needs to be repeated n times to get as if n "layers" of the matrix depicted in Fig. 7.

Moreover, in the second embodiment of the method according to the present invention, the following operations are performed, other than the operations of the closest analogue:

form an estimate of the magnitude of the received impulse at a particular point in time for each reference direction from a pre-selected finite set of reference directions in the angular control sector, and this estimate of the magnitude of the received impulse is formed by summing the signals on the set of taps corresponding to the selected specific moment in time, 6 delay lines in each from observation channels 1;

find an estimate of the shape of the received pulse from the formed estimates of the magnitude of the received pulse for various specific times;

using the found estimate of the shape of the received pulse as a reference signal in multi-channel correlation processing;

on the set of results of multichannel correlation processing, a correlation maximum is selected, which is used as a threshold threshold statistics in the target detection procedure;

estimate the direction of arrival of the reflected pulses in a predetermined angular control sector using an interpolation estimate of the position of the correlation maximum in the vicinity of that reference direction from the selected set of reference directions for which the greatest result of multichannel correlation processing is obtained.

используемому в теореме отсчетов Котельникова-Найквиста. Наиболее простой является линейная интерполяция. Она относится к большому классу интерполяционных оценок, базирующихся на ограниченном числе опорных точек, связываемых с нужной промежуточной (интерполируемой) позицией. В основе таких методов лежит свойство, заключающееся в том, что при некотором «запасе» по частоте дискретизации (например, для линейной интерполяции указанный «запас» подразумевает превышение граничного значения Котельникова-Найквиста в 2-2,5 раза) можно с большой степенью точности восстановить форму сигнала с помощью линейных комбинаций. В этом случае отпадает необходимость учитывать все сигналы, присутствующие на отводах линий 6 задержки для восстановления состояния в промежуточной позиции, достаточно использовать только опорные точки, совпадающие с границами интервала времени, в который попадает промежуточный момент. На фиг.8 показана блок-схема по фиг.7 для случая линейной интерполяции сигнала в промежуточных позициях для заданного опорного направления. При этом число операций взвешивания, равное в общем случае M(L+1), сократится до 2М. При такой линейной интерполяции находят веса линейных комбинаций сигналов на выходах элементов 7 задержки в разных каналах 1 наблюдения и используют эти найденные веса линейных комбинаций сигналов для формирования условных оценок формы принимаемых импульсов на заданном множестве дискретных временных позиций, согласующихся с одним из выбранного множества опорных направлений.Shown in Fig. 7, an example of controlling support directions using weight processing is common to the second variant of the target location method under consideration. To simplify this flowchart, various interpolation methods can be used, for example, methods for reconstructing signals at intermediate times using a quadratic formula or using a system of impulse functions proportional to the expression

used in the Kotelnikov-Nyquist counting theorem. The simplest is linear interpolation. It belongs to a large class of interpolation estimates based on a limited number of control points associated with the desired intermediate (interpolated) position. Such methods are based on the property that with a certain “margin” in sampling frequency (for example, for linear interpolation, the indicated “margin” implies 2–2.5 times exceeding the Kotelnikov – Nyquist boundary value) with a high degree of accuracy restore waveform using linear combinations. In this case, there is no need to take into account all the signals present on the taps of the delay lines 6 to restore the state in the intermediate position, it is enough to use only reference points that coincide with the boundaries of the time interval at which the intermediate moment falls. On Fig shows the block diagram of Fig.7 for the case of linear interpolation of the signal at intermediate positions for a given reference direction. Moreover, the number of weighing operations, which is generally equal to M (L + 1), will be reduced to 2M. With such linear interpolation, weights of linear signal combinations are found at the outputs of delay elements 7 in different observation channels 1 and these found weights of linear signal combinations are used to form conditional estimates of the shape of the received pulses at a given set of discrete time positions consistent with one of the selected set of reference directions.

Unlike the known methods, the joint algorithm synthesized above is designed to operate under conditions when the shape of the received signal and the direction of its arrival are unknown.

According to this algorithm, a specialist can compile appropriate programs for computer processing. These programs are on computer readable media, i.e. being converted into software products, when executed on a computer, they will ensure the implementation of the corresponding method of target location by processing reflected pulses as described above.

Industrial applicability

The present invention can be used in radar, optical, ultrasonic and any other location that uses the sounding of space ultra-wideband pulses. In particular, the present invention can find application in the detection of various targets, for example, air or space, as well as in seismography, tomography, when probing the earth's interior, sea depths and atmosphere.

The examples of the implementation of the method of the present invention are only illustrations and do not limit the scope of patent claims, which is determined only by the attached claims taking into account all possible equivalents.

Claims (6)

1. The method of location of the target, which consists in the fact that emit ultra-wideband pulses by the array of antenna elements; when receiving reflected pulses in a predetermined angular monitoring sector, the signal received by each antenna element of said array of antenna elements is delayed with the help of series-connected delay elements in each of the plurality of observation channels used; carry out a target detection procedure by using multi-channel correlation signal processing at the outputs of said delay elements in different said observation channels; characterized in that, when said multi-channel correlation processing of signals, the shape of the received pulse is estimated at a plurality of discrete time positions by averaging over said observation channels for signals on subsets of the outputs of those said delay elements that correspond to the same discrete time in different said observation channels position at a known direction of arrival of the reflected pulses in the aforementioned predetermined angular sector of control; using the found estimate of the shape of the received pulse as a reference signal in said multi-channel correlation processing. 2. The method of location of the target, which consists in the fact that emit ultra-wideband pulses by the array of antenna elements; when receiving reflected pulses in a predetermined angular monitoring sector, the signal received by each antenna element of said array of antenna elements is delayed with the help of series-connected delay elements in each of the plurality of observation channels used; carry out a target detection procedure by using multi-channel correlation signal processing at the outputs of the delay elements in the various mentioned observation channels, characterized in that, when the multi-channel correlation signal processing is mentioned, an estimate of the magnitude of the received pulse at a particular time for each reference direction from a pre-selected finite set of reference directions in the angular control sector, and the aforementioned estimate of the magnitude of the received impulse form by averaging over the observation channels the signal samples on the subsets of the outputs of the said delay elements, which for a given reference direction in the various said monitoring channels correspond to the same discrete time position; find an estimate of the shape of the received pulse from the formed estimates of the magnitude of the received signal for various discrete time instants; using the found estimate of the shape of the received pulse as a reference signal in said multi-channel correlation processing; on the plurality of results of said multichannel correlation processing, a correlation maximum is selected, which is used as pre-threshold decision statistics in said target detection procedure; estimate the direction of arrival of the reflected pulses in said predetermined angular control sector using an interpolation estimate of the position of said correlation maximum in the vicinity of that reference direction from said selected set of reference directions for which the greatest result of said multi-channel correlation processing is obtained. 3. The method according to claim 2, characterized in that said formation of a plurality of signal samples in each of said observation channels is carried out using linear interpolation due to the fact that the weights of linear signal combinations are found at the outputs of said delay elements in different said observation channels and used these found weights of linear signal combinations for forming conditional estimates of the shape of the received pulses at a given set of discrete time positions consistent with one of the selected many support directions. 4. A software product that is executed on a computer in a target location method in which ultra-wideband pulses are emitted by an array of antenna elements; when receiving reflected pulses in a predetermined angular monitoring sector, the signal received by each antenna element of said array of antenna elements is delayed with the help of series-connected delay elements in each of the plurality of observation channels used; carry out a target detection procedure by using multi-channel correlation signal processing at the outputs of said delay elements in the various said observation channels; wherein said software product performs said multichannel correlation processing of signals, during which the shape of the received pulse is estimated at a plurality of discrete time positions by averaging over said observation channels for signals on subsets of the outputs of said delay elements that correspond in different said observation channels to of the same discrete time position with a known direction of arrival of reflected pulses in the aforementioned anee predetermined angular control of the sector; using the found estimate of the shape of the received pulse as a reference signal in said multi-channel correlation processing. 5. A software product that is executed on a computer in a target location method in which ultra-wideband pulses are emitted by an array of antenna elements; when receiving reflected pulses in a predetermined angular monitoring sector, the signal received by each antenna element of said array of antenna elements is delayed with the help of series-connected delay elements in each of the plurality of observation channels used; carry out a target detection procedure by using multi-channel correlation signal processing at the outputs of said delay elements in the various said observation channels; wherein said software product performs said multichannel correlation signal processing, during which an estimate of the magnitude of the received pulse at a point in time is generated for each reference direction from a pre-selected finite set of reference directions in the angular control sector, and said estimate of the magnitude of the received pulse is formed by averaging over observation channels of signal samples on the subsets of outputs of the mentioned delay elements, which for a given th reference direction in different channels of said observations correspond to the same discrete time slot; find an estimate of the shape of the received pulse from the formed estimates of the magnitude of the received signal for various discrete time instants; using the found estimate of the shape of the received pulse as a reference signal in said multi-channel correlation processing; on the plurality of results of said multichannel correlation processing, a correlation maximum is selected, which is used as pre-threshold decision statistics in said target detection procedure; estimate the direction of arrival of the reflected pulses in said predetermined angular control sector using an interpolation estimate of the position of said correlation maximum in the vicinity of that reference direction from said selected set of reference directions for which the greatest result of said multi-channel correlation processing is obtained. 6. The software product according to claim 5, characterized in that said formation of a plurality of signal samples in each of said observation channels is carried out by linear interpolation due to the fact that the weights of linear signal combinations are found at the outputs of said delay elements in different said observation channels and use these found weights of linear signal combinations to form conditional estimates of the shape of the received pulses at a given set of discrete time positions, consistent with one of the mentioned The selected set of reference directions.

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