RU2416105C1 - Method of determining motion parametres of aerial objects in surveillance radar by using coherent properties of reflected signals - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention employs the principle of compensating for phase incursions caused by movement of aerial objects by multiplying received signals by a special phase multiplier, which also takes into account the possibility of the object having radial and tangential velocity components. If a compensating phase multiplier is correctly chosen, reflected signals become in-phase and the vector of their coherent addition becomes maximum. True values of radial and tangential velocity components of the object are established based on maximisation of the coherent sum of reflected signals.

EFFECT: reliable detection of objects and measurement of their motion parametres over time comparable with the period of one revolution of the antenna on the azimuth, within the entire aerial space and independent of the type of engines of the aerial objects and direction of their motion.

7 dwg

Description

The invention relates to the field of radar detection of objects and measuring the parameters of their movement in radar stations (radars), carrying out a sequential circular overview of the space.

A known method for determining the motion parameters of airborne objects in surveillance radars through the use of coherent properties of the reflected signals [1, p.303], based on the following operations.

1. Reception of a reflected signal from an airborne object (AT) during a circular overview of airspace, and the reflected signal has the form:

- число импульсов, принимаемых за один круговой обзор; int{·} - символ вычисления целого значения числа в фигурных скобках {·}; Т_обз - период обзора пространства по азимуту, β_во - истинный азимут воздушного объекта, находящегося на дальности r_k=kΔr, т.е. находящегося в k-м

элементе разрешения по дальности Δr;

- текущее азимутальное положение максимума (центра) ХНА в момент времени t_n; V_r - радиальная составляющая вектора скорости ВО; V_τ - тангенциальная составляющая вектора скорости ВО; I - число рассеивающих центров (РЦ) на поверхности ВО; i - номер РЦ

- комплексное значение аддитивной суммы внешних шумов (помех), внутренних шумов приемника и шумов квантования принятого сигнала в k-м элементе разрешения по дальности в момент времени t_n; U_i - амплитуда отражения зондирующего сигнала от i-го РЦ; Ψ_i - фаза переотражения радиоимпульса от i-го РЦ в совокупности с начальной фазой излучения зондирующего сигнала; t_i - время, учитывающее частную задержку сигнала при отражении от i-го РЦ поверхности ВО (учет разных наклонных дальностей до разных РЦ); верхний или нижний индекс «k» обозначает принадлежность параметра к k-му элементу разрешения по дальности.where G [β _in -β (t _n )] is the current value of the directivity characteristic of the antenna (XNA) in the direction of the HE at the time t _n = nT _and , n is the number of the pulse repetition period T _{and the} radar in which the reflected signal was received ;

- the number of pulses taken in a single circular review; int {·} - a symbol for calculating the integer value of a number in curly braces {·}; T _obz - the period of viewing the space in azimuth, β _in - the true azimuth of an airborne object at a range of r _k = kΔr, i.e. located in the kth

range resolution element Δr;

- the current azimuthal position of the maximum (center) of the XNA at time t _n ; V _r is the radial component of the velocity vector IN; V _τ is the tangential component of the velocity vector VO; I is the number of scattering centers (RC) on the surface of the HE; i is the number of the RC

- the complex value of the additive sum of external noise (interference), internal noise of the receiver and quantization noise of the received signal in the k-th element of resolution in range at time t _n ; U _i - the reflection amplitude of the probe signal from the i-th RC; Ψ _i is the phase of rereflection of the radio pulse from the i-th RC in combination with the initial phase of the radiation of the probe signal; t _i is the time taking into account the partial delay of the signal during reflection from the i-th RC of the BO surface (taking into account different slant ranges to different RCs); superscript or subscript “k” denotes that the parameter belongs to the kth range resolution element.

2. Registration of the quadrature components of the received signal, the calculation of its complex form and recording in the random access memory (RAM) of the radar.

3. Measurement of the delay time t _{s1 of the} received signal (1) and the determination of the range to VO R ₁ during the first review of the space by the formula

where c is the propagation velocity of radio waves.

4. The determination of the range to VO R ₂ in the second survey of space and the calculation of the radial velocity of the object by the formula

5. The calculation of the magnitude of the change in azimuth Δβ, which determines the difference between the two angular positions in the second β ₂ and first β ₁ space surveys by the formula

6. Determination of the tangential velocity V _τ VO from the calculated values of Δβ, t _z1 and t _z2 (cosine theorem):

7. The calculation of the total velocity vector (linear velocity) VO according to the formula

8. The calculation of the heading angle in the formula

радиальной скорости V_r движения ВО определяется выражением [2, с.278]Moreover, the accuracy of the assessment

the radial velocity V _{r of the} motion of VO is determined by the expression [2, p.278]

τ_и - длительность зондирующего радиоимпульса; q - отношение сигнал/шум в приемном устройстве радиолокатора.Where

τ _and is the duration of the probe radio pulse; q is the signal-to-noise ratio in the radar receiver.

For the trajectory of an object moving with acceleration for m equally discrete and uniform measurements, the accuracy of the estimation of the tangential velocity V _τ can be determined by the formula [2, p.268-278]

An analysis of the expressions presented shows that in order to obtain an acceptable accuracy in estimating the velocity parameters of the HE movement (radial and tangential velocities), it is necessary to conduct at least 5-6 range measurements, which takes a long time with a circular survey (viewing the space in azimuth). And while saving time for measurement, the accuracy of estimates of motion parameters becomes low.

To improve the accuracy of determining the parameters of the HE movement for a fixed time of viewing the space and to reduce the measurement time for a given accuracy of the estimation of the parameters of motion, an improved method was proposed for determining the parameters of the motion of HE in survey radars by using the coherent properties of the signals reflected by objects [3].

рассчитывают по формулеThe method [3] consists in the fact that using a survey radar during a circular azimuthal scanning, the HVA emit sounding signals into space, receive signals reflected by an airborne object, register the quadrature components of the received signals, calculate their complex shape, record the quadrature components of the received signals in RAM, determine the distance to the object at each survey of space by the formula (2), form in RAM N matrices of reference signals (MOS) H _{n of} size P × L, the elements of which

calculated by the formula

- номер МОС, соответствующий номеру принятого в процессе обзора отраженного объектом сигнала; N_обз - количество принимаемых в процессе одного азимутального обзора отраженных объектом сигналов;

и

- соответственно значения подбираемых расчетом радиальной и тангенциальной составляющих линейной скорости ВО V_во; {·} - знак множества; ΔV_r и ΔV_τ - величины шагов дискретизации расчетных радиальной

и тангенциальной

составляющих линейной скорости ВО соответственно;

- текущий номер для дискретного подбора

; L=V_{r max}/ΔV_r - количество расчетных значений скорости

; V_{r max} - максимально возможное значение радиальной скорости ВО;

- текущий номер для дискретного подбора

; P=V_{τ max}/ΔV_τ - количество расчетных значений скорости

; V_{τ max} - максимально возможное значение тангенциальной скорости

; умножают каждый элемент n-й МОС H_n на соответствующий n-й комплексный принятый сигнал; формируют матрицу результирующих сигналов (МРС) Н_рез размером P×L путем суммирования одноименных (с равными индексами) элементов n-х МОС H_n после перемножения элементов

с величинами соответствующих (по номеру n) принятых сигналов

по формулеWhere

- MOS number corresponding to the number of the signal received during the review of the signal reflected by the object; N _review - the number received in the process of one azimuthal survey of the signals reflected by the object;

and

- respectively, the values selected by the calculation of the radial and tangential components of the linear velocity VO V _in ; {·} Is the sign of the set; ΔV _r and ΔV _τ are the discretization steps of the calculated radial

and tangential

components of the linear velocity VO, respectively;

- current number for discrete selection

; L = V _{r max} / ΔV _r is the number of calculated speed values

; V _{r max} - the maximum possible value of the radial velocity VO;

- current number for discrete selection

; P = V _{τ max} / ΔV _τ is the number of calculated speed values

; V _{τ max} - the maximum possible value of the tangential velocity

; multiply each element of the nth MOS H _n by the corresponding nth complex received signal; form a matrix of the resulting signals (MRS) N _cut size P × L by summing the same (with equal indices) elements of the n-th MOS H _n after multiplying the elements

with the values of the corresponding (by number n) received signals

according to the formula

calculate the square of the module of each element of the MPC N _res , determine in the MPC N _res row number p ₀ and column l ₀ , which corresponds to the largest value of the square of the module of its element, i.e. the square of the modulus of the complex number contained in this element; calculate the radial and tangential components of the speed of the air object according to the formulas: V _r = ΔV _r p ₀ and V _τ = ΔV _τ l ₀ .

The specified method provides higher accuracy characteristics of the measurement of the radial and tangential components of the speed of movement of air objects, as well as reducing the time for measuring V _r and V _τ . However, it is characterized by the following significant disadvantages.

1) The method involves the addition of N received in the process of reviewing the signals for each k-th element of resolution in range. However, a significant contribution to the measurement process is made only by those signals that were obtained by radar contact with the object of the main lobe of the XNA, i.e. the number N of reference signal arrays should be substantially smaller than the number of pulses emitted per revolution of the antenna. When using all the signals received for the review, the speed estimate will be distorted by the noise and signals of other objects located at the same range, but at a different azimuth. Therefore, the number of MOS used by the method should be clarified and justified.

2) The method involves measuring the HE parameters at various azimuths and ranges, however, the approach to providing information about different objects is not presented in the method, which contradicts the purpose (tasks) of the survey radars.

3) The method involves the preliminary detection of objects and false signals, although potentially the method itself, in accordance with its logic and capabilities, is capable of simultaneously detecting objects and measuring their motion parameters.

4) The speed components in the presented way will be determined for those pulsed volumes of space where there are no objects, since one of the elements of the MPC will always have the maximum value. This leads to unreasonable overload of the radar computing system and can be used only if the calculation will additionally solve the problem of detecting VO within the entire space.

5) The method involves the addition of complex signals, i.e. coherent addition of signals taking into account the phase, ignoring the consideration and accounting of phase shifts due to reflections from the rotating elements of the VO propulsion systems. Therefore, the method is limitedly operable and effective only in respect of HE, in which the rotating elements of the engines are absent (for example, a projectile, balloon, rocket).

и

Однако ВО бывают удаляющимися и приближающимися, а также движущимися влево и вправо относительно линии визирования. А радиолокатор нуждается в измерении любых из указанных скоростей, в том числе и отрицательных.6) The method takes into account the presence of only positive speeds and their components

and

However, VOs are moving away and approaching, as well as moving left and right relative to the line of sight. A radar needs to measure any of these speeds, including negative ones.

и

используются переменные L и Р соответственно. Значит, расчет значений составляющих скорости ВО следовало бы проводить по формулам V_r=ΔV_rl₀ и V_τ=ΔV_τp₀, а не по формулам V_r=ΔV_rp₀ и V_τ=ΔV_τl₀, как указано в [3]. При использовании указанных в [3] формул оценки составляющих скорости будут неверными (ошибочными), подменяющими друг друга.7) Both in the formula and in the description of the prototype [3] for sampling the calculated values

and

variables L and P are used respectively. Therefore, the calculation of the components of the velocity VO should be carried out according to the formulas V _r = ΔV _r l ₀ and V _τ = ΔV _τ p ₀ , and not according to the formulas V _r = ΔV _r p ₀ and V _τ = ΔV _τ l ₀ , as indicated in 3]. When using the formulas indicated in [3], estimates of the velocity components will be incorrect (erroneous), replacing each other.

The objective of the invention is to improve the method for determining the motion parameters of airborne objects in surveillance radars (through the use of coherent properties of the reflected signals) in the interests of:

ensuring the simultaneous solution of the problems of detecting objects and measuring the parameters of their movement for the entire volume of air space adjacent to the radar;

equally effective measurement of the motion parameters of objects containing and not containing propulsion systems with rotating elements;

providing measurements of the speeds of objects in the entire objectively existing range of their changes.

To solve this problem, it is proposed to determine the minimum additional number of reflected signals for each azimuthal position, to carry out low-pass filtering of the reflected signals before processing them according to the main content of the method, and also to provide a comparison of the measured velocity components V _r and V _τ for adjacent azimuthal antenna positions.

Let us designate the required number of summable (coherently added) signals of the variable G. To determine the value of G, we consider the time of radar contact of the main lobe of the XNA with VO, which we will call the accumulation time T _n . This time is the ratio of the width Δθ _{β of the} main lobe of the radar detector in azimuth to the angular velocity of rotation of the antenna ω _obz (in the case of electronic scanning, to the angular velocity of the ray of the XNA in space) when viewing the space

Then the number of pulses G taken during the contact time of the main beam of the XNA with VO can be determined by the formula

where int2 {•} is the symbol of the rounding operation to the nearest integer even number. Parity G is claimed by subsequent operations.

In typical radar survey meter range HENNA width of the main beam of the order of 8 °, a pulse repetition period _{T, and} is a few milliseconds. This means that for T _and = 2.6 ms at an antenna rotation speed of 2, 4 or 6 revolutions per minute (which corresponds to the review periods T _{review of} 30, 15 and 10 s), 240, 120 or 85 pulses can be accumulated during T _n , respectively.

According to the proposed method, for each n-th azimuthal position of the normal antenna β (t _n ), it is required to accumulate and write G pulses into the RAM memory. If the BO were in the azimuthal position β (t _n ), that is, in the position corresponding to the normal position of the antenna when the nth pulse is emitted, then the pack of accumulated pulses (all of them G) would have to start with the pulse with the number (nG / 2), and it should end with an impulse with the number (n + G / 2). We will use these considerations to describe the proposed method.

. Число азимутальных элементов одного обзора N_обз определяется числом импульсов, излучаемых за один обзор: N_обз=int{T_oбз/T_и}. Каждому азимутальному элементу соответствует свой n-й период излучения импульсов, т.е. свое время излучения t_n. Поэтому текущее азимутальное положение нормали антенны в момент времени t_n будем обозначать β(t_n). На фиг.1 использованы следующие обозначения: 1 - точка расположения (стояния) радиолокатора; 2 - азимутальное положение антенны в момент времени t_n; 3 - положение k-го элемента разрешения по дальности; 4 - диаграмма направленности антенны.In accordance with the idea of the proposed method, the entire airspace surrounding the surveillance radar is proposed to be divided into long-range and azimuthal elements. The number of range elements K is determined by the range to the near r _b and the far r _d borders of the radar detection zone (Fig. 1), as well as the magnitude of the range resolution element Δr, which is expressed by the dependence

. The number of azimuthal elements of one survey N _obz is determined by the number of pulses emitted in one review: N _obz = int {T _obz / T _and }. Each azimuthal element corresponds to its nth period of pulse emission, i.e. its radiation time t _n . Therefore, the current azimuthal position of the antenna normal at time t _n will be denoted by β (t _n ). In Fig. 1, the following notation is used: 1 - point of location (standing) of the radar; 2 - azimuthal position of the antenna at time t _n ; 3 - position of the k-th element of range resolution; 4 is an antenna pattern.

т.е. для (N_обз+G) азимутальных положений антенны. Для этого в каждом из периодов повторения импульсов (всего их в указанном диапазоне G+N_обз) после приема отраженных сигналов предлагается проводить согласованную обработку (фильтрацию) сигналов во всем интервале времени приема [4, 5, 6], т.е. с временами задержки, соответствующими интервалу дальности от r_б до r_д (фиг.1). Согласованная обработка может быть выполнена в аналоговом виде с помощью квазиоптимального фильтра или после перевода принятой реализации в цифровой вид путем свертки с комплексно-сопряженным оцифрованным зондирующим сигналом этого же периода [4, 5, 6]. Согласованная обработка должна заканчиваться низкочастотной фильтрацией огибающих отраженных сигналов. Назначение этой операции будет раскрыто ниже.In order to ensure simultaneous detection of objects and measurement of parameters of their motion, it is proposed, first of all, to digitize all signals received in the range of azimuth from β [t _{(-G / 2)} ] to

those. for (N _review + G) azimuthal antenna positions. For this, in each of the pulse repetition periods (all of them in the indicated range G + N _review ) after receiving the reflected signals, it is proposed to carry out a coordinated processing (filtering) of signals in the entire reception time interval [4, 5, 6], i.e. with delay times corresponding to the range interval from r _b to r _d (figure 1). Coordinated processing can be performed in analog form using a quasi-optimal filter or after converting the accepted implementation to digital form by convolution with a complex conjugate digitized sounding signal of the same period [4, 5, 6]. Consistent processing should end with low-pass filtering of the envelopes of the reflected signals. The purpose of this operation will be disclosed below.

The entire sequence of the adopted implementation within the repetition period is divided into elements corresponding to the elements of resolution in range Δr. In digital form, the range resolution element is each point (pixel) in the received signal implementation from r _b to r _d .

Then, for each of the range resolution elements Δr and for each of the azimuthal positions β (t _n ), the quadrature components of the signals are recorded, the complex shape of each signal is calculated, and it is recorded in the radar RAM by analogy with the prototype method [3].

Next, the operations are the same for all range resolution elements, in connection with which we consider only one kth range resolution element. For the k-th range resolution element (range element), a private array of complex numbers of length (N _overview + G) corresponding to different azimuthal positions of the XNA within the considered range resolution element, starting from the azimuth β [t _{(- G / 2)} ] and ending in azimuth

, где верхний индекс «k» указывает на соответствие k-му элементу дальности. Каждая такая g-я матрица

включает в себя P×L элементов

т.е.

Similarly to the method [3], in advance for the k-th range element, G matrices of reference signals are composed

, where the superscript “k” indicates correspondence to the kth range element. Each such gth matrix

Includes P × L Elements

those.

, L=2V_{r max}/ΔV_r,

,where P = 2V _{τ max} / ΔV _τ ,

, L = 2V _{r max} / ΔV _r ,

,

and the values of the matrix elements are calculated by the formula

where r _k is the range corresponding to the kth resolution element under consideration (r _k = kΔr).

для k-го элемента дальности.Figure 2 presents a parallelogram, each element (small cube) which corresponds to one of the calculated values of the reference signal for the k-th element of the range. A vertical slice of a parallelogram corresponds to one of the generated matrixes of reference signals. In total, there are G such various vertical slices. The number of rows in the slice is P, and the number of columns is L. From obvious considerations, it is clear that the steps ΔV _r and ΔV _τ must be equal, which determines the equality P = L. Presented in figure 2 parallelogram graphically interprets the order of formation of G matrices of reference signals

for the kth element of range.

и

для каждого азимутального положения антенны β^k(t_n) в каждом k-м элементе дальности. Порядок получения оценок

и

следующий.The proposed method is designed to generate estimates

and

for each azimuthal position of the antenna β ^k (t _n ) in each k-th element of the range. The procedure for obtaining ratings

and

following.

и заканчивая сигналом

. Затем, используя величины элементов

MOC и величины отраженных сигналов, для каждого азимутального положения β^k(t_n) формируют матрицу результирующих сигналовAlternately, the current azimuth value β ^k (t _n ) is recorded in the kth range resolution element. This current value is taken as the middle of the interval T _n for which the complex values of the reflected signal are obtained. That is, for the selected azimuth position β ^k (t _n ), G signals are selected from the entire array of complex reflected signals, starting with the signal

and ending with a signal

. Then, using element values

MOC and values of the reflected signals, for each azimuthal position β ^k (t _n ) form a matrix of the resulting signals

elements of which are calculated by the formula

c разными номерами g.where the index "∑" means that the complex addition of the products of the same number by p and l

with different numbers g.

определяют номер строки

и столбца

того элемента, модуль которого максимален. В способе-прототипе [3] для определения такого элемента использован квадрат модуля, что ничем не обосновано и требует расхода дополнительного вычислительного ресурса. С помощью установленных номеров

и

рассчитывают радиальную и тангенциальную составляющие скорости воздушного объекта, нахождение которого предполагается на азимуте β^k(t_n) и дальности r_k. Расчет проводят по формуламFurther, similar to the prototype among all the elements of the resulting resulting matrix

determine the line number

and column

of the element whose modulus is maximum. In the prototype method [3], a module square was used to determine such an element, which is unreasonable and requires the consumption of additional computing resource. Using the set numbers

and

calculate the radial and tangential components of the speed of an air object, the location of which is assumed at the azimuth β ^k (t _n ) and range r _k . The calculation is carried out according to the formulas

и

.So, sequentially changing the considered azimuthal position β ^k (t _n ), for each specific azimuth and k-th element of the range determine the values of the estimates of the components

and

.

и

для смежных азимутальных положений антенны (например, для β^k(t₅) и β^k(t₆)) в случае наличия ВО на соответствующем азимуте будут совпадать, проводят последовательное сравнение оценок составляющих скорости

и

В результате сравнения находят совокупность смежных азимутальных положений с одинаковыми значениями оценок составляющих скорости

и

Фиксируют начальное β^k(t_нач) и конечное β^k(t_кон) значения азимута с одинаковыми оценками составляющих скорости.The obtained estimates of the velocity components are used to solve the problem of detecting HE. Detection is also carried out within each k-th element of the range. Given the fact that the estimates of the components

and

for adjacent azimuthal antenna positions (for example, for β ^k (t ₅ ) and β ^k (t ₆ )) in the case of the presence of VO at the corresponding azimuth, they will coincide, conduct a sequential comparison of estimates of the velocity components

and

As a result of the comparison, a set of adjacent azimuthal positions is found with the same values of the estimates of the velocity components

and

The initial β ^k (t _beg ) and final β ^k (t _con ) azimuth values are fixed with the same estimates of the velocity components.

и

если в их совокупность не входит β^k(t₁). Наибольшее из значений азимутов с одинаковыми оценками

и

считают в этом случае конечным значением β^k(t_кон). Если же β^k(t₁) входит в совокупность азимутальных значений с одинаковыми оценками

и

то предварительно разделяют всю совокупность выделенных азимутальных положений на две части А и В, первая из которых А со смежными нарастающими номерами n дискретов времени t_n заканчивается азимутальным положением

, а вторая В со смежными нарастающими номерами n дискретов времени t_n начинается значением β^k(t₁). Азимутальное положение с наименьшим значением азимута (с наименьшим номером n) из части А принимают в качестве β^k(t_нач), а азимутальное положение с наибольшим значением азимута (с наибольшим номером n) из части В - в качестве β^k(t_кон).In this case, the initial value of β ^k (t _beg ) is considered the smallest of the azimuths with the same estimates

and

if their combination does not include β ^k (t ₁ ). The largest of the azimuths with the same ratings

and

consider in this case the final value of β ^k (t _con ). If β ^k (t ₁ ) is included in the set of azimuthal values with the same estimates

and

then the whole set of selected azimuthal positions is preliminarily divided into two parts A and B, the first of which A with adjacent increasing numbers of n time discs t _n ends with the azimuthal position

and the second B with adjacent increasing numbers of n discrete time t _n begins with the value β ^k (t ₁ ). The azimuthal position with the lowest azimuth value (with the lowest number n) from part A is taken as β ^k (t _beg ), and the azimuthal position with the lowest azimuth value (with the lowest number n) from part B is taken as β ^k (t _con ) .

по формулам:Calculate the true azimuthal position of VO

according to the formulas:

при отсутствии между β^k(t_нач) и β^k(t_кон) первого значения азимута

but)

in the absence of a first azimuth value between β ^k (t _beg ) and β ^k (t _con )

при наличии между β^k(t_нач) и β^k(t_кон) первого значения азимута β(t₁), которое встречается, если совершать изменение азимута по часовой стрелке от β^k(t_нач) до β^k(t_кон).b)

if there is a first azimuth value β (t ₁ ) between β ^k (t _beg ) and β ^k (t _con ), which occurs if the azimuth is changed clockwise from β ^k (t _beg ) to β ^k (t _con ).

находится ВО.Decide that in the kth element, the range resolution in azimuth

is in.

(рассчитанных по правилу расчета гипотенузы в прямоугольном треугольнике с катетами, равными

и

), их радиальных и тангенциальных составляющих выводят на дисплей для доведения до обслуживающего персонала радиолокатора, а соответствующие элементы дальности и азимута маркируют (помечают) на индикаторе кругового обзора радиолокатора яркостными отметками.Information about all detected HE with an indication of their respective ranges r _k , azimuths β ^k (t _n ), linear velocities

(calculated according to the rule for calculating hypotenuse in a right triangle with legs equal to

and

), their radial and tangential components are displayed to bring the radar to the operating personnel, and the corresponding range and azimuth elements are marked (marked) on the indicator of the radar circular view with brightness marks.

In addition, for a complete solution of the problem, it is proposed to receive low-pass filtering of this reflected signal after receiving the reflected signal before applying it for digitization to an analog-to-digital converter (ADC). This is necessary to neutralize high-frequency turboprop modulation. For low-pass filtering, it is advisable to provide for the presence of a low-pass narrow-band filter at the input of the ADC. The purpose of the filter is to skip a useful informative low-frequency signal and eliminate the high-frequency component of the signal. For this, the passband of the filter used must be less than the frequency of the first turboprop components of the spectrum of the reflected signal. Since the frequencies of the components of the turboprop effect (TVE) lie in the range from units to hundreds of kHz [7, 8], it is advisable to set the filter passband in the range of 0-300 Hz. When passing through such a filter, the sequence of reflected signals with an envelope modulated by turboprop components (Fig. 3, a) gets rid of the negative influence of the fuel cell, i.e. loses high-frequency turboprop modulation (figure 3, b).

Thus, it is proposed to construct an improved method for determining the parameters of the movement of airborne objects in survey radars (by using the coherent properties of the reflected signals) in the form of a logical sequence of the following operations.

1) In advance, calculate the number of pulses G received from one azimuthal direction by the main lobe of the XRD of the survey radar according to the formula (13)

where int2 {•} is the symbol of the rounding operation to the nearest even integer; T _obz - the period of viewing the space in azimuth; Δθ _β is the width of the main lobe of the XRD radar in azimuth; T _and - the repetition period of the probe pulses used in the radar.

2) The probes are emitted and reflected signals are received in the azimuthal range, starting from the azimuth (-Δθ _β / 2) and ending after one full revolution in the azimuth (2π) with the azimuthal position (2π + Δθ _β / 2), and when receiving the reflected signals of each the repetition period T _and in RAM, fix the value of the corresponding azimuth β (t _n ) of the antenna at time t _n , where the value of n varies within (-G / 2) ... (N _review + G / 2).

3) Each received signal is passed through a low-pass filter with a passband of 0-300 Hz to eliminate high-frequency turboprop modulation.

соответствует вполне определенное азимутальное положение антенны β(t_n) и дальность r_k=Δrk.4) The quadrature components of the reflected signals of each repetition period are recorded in digital form, their complex shape is calculated and these values are recorded in RAM, and the reflected signals of the nth period are recorded in a data array corresponding to the nth azimuthal position β (t _n ) and having K cells (elements) by the number of range resolution elements K = (r _d -r _b ) / Δr, where r _b is the near boundary of detection of objects, r _d is the far boundary of detection of objects, Δr is the value of the resolution element in range. As a result, all received signals become marked, i.e. each received signal

corresponds to the well-defined azimuthal position of the antenna β (t _n ) and the range r _k = Δrk.

будут соответствовать азимутальным положениям, изменяющимся от (-Δθ_β/2) до (2π+Δθ_β/2), т.е. с учетом одного полного оборота антенны по азимуту (вкруговую). Всего будет образовано К таких МР.5) Combine the received signals corresponding to the same ranges into separate implementation arrays (MR), in each of which the complex values of the reflected signals received at different azimuthal positions, but at the same range, will be recorded. Elements of the k-th MP

will correspond to azimuthal positions varying from (-Δθ _β / 2) to (2π + Δθ _β / 2), i.e. taking into account one full revolution of the antenna in azimuth (circular). In total, K such MRs will be formed.

, где верхний индекс «k» указывает на соответствие k-му элементу дальности, т.е. k-й дальности r_k. При этом каждая g-я МОС

включает в себя P×L элементов, 6) For each k-th element of range resolution and the corresponding k-th MR, G matrices of reference signals are generated

, where the superscript "k" indicates the correspondence to the kth range element, i.e. kth range r _k . Moreover, each gth MOS

includes P × L elements,

, where P = 2V _{τ max} / ΔV _τ ,

,

L = 2V _{r max} / ΔV _r ,

.

.

элементы которой

рассчитывают по формуле7) For each element with the number n from 1 to N, the _{overview of} each k-th MR form the corresponding n-th MRS

elements of which

calculated by the formula

определяют номер строки

и столбца

, которым соответствует элемент с максимальным модульным значением в пределах соответствующей МРС

.8) Among the elements of each n-th MPC

determine the line number

and column

which corresponds to an element with a maximum modular value within the corresponding MPC

.

и

рассчитывают радиальные и тангенциальные составляющие скорости воздушных объектов, которые предположительно (гипотетически) находятся в элементах пространства, соответствующих k-й дальности r_k и азимуту β(t_n), по формулам

и

9) Using the set numbers

and

calculate the radial and tangential components of the speed of air objects, which are supposedly (hypothetically) located in the space elements corresponding to the k-th range r _k and azimuth β (t _n ), according to the formulas

and

10) Write down the estimates of the radial and tangential velocity components of each k-th range resolution element in a three-dimensional array M ^k (Fig. 4), in the first line of which the number n is placed, in the second - the corresponding estimates of the radial velocity, in the third - the corresponding estimates of the tangential speed.

, а также с совпадающими между собой значениями

фиксируют начальный

и конечный

номера, для которых получены одинаковые оценки составляющих скорости в k-м элементе разрешения по дальности, где индекс «m» означает номер частного подмножества (частного интервала) элементов с одинаковыми оценками составляющих скорости (в пределах массива M^k, т.е. k-го элемента дальности, может оказаться несколько ВО на разных азимутах). При этом последний и первый столбцы массива M^k также считают смежными.11) Within each array M ^k , elements with adjacent numbers are compared and, in the presence of two or more consecutive columns with the same values

, as well as matching values

fix the initial

and final

numbers for which the same estimates of the velocity components in the k-th range resolution element are obtained, where the index “m” means the number of the private subset (private interval) of elements with the same estimates of the velocity components (within the array M ^k , i.e., k- th element of range, there may be several VOs at different azimuths). Moreover, the last and first columns of the array M ^{k are} also considered adjacent.

а также с совпадающими между собой оценками

не включает крайние столбцы (фиг.5), то начальный номер

присваивают столбцу из выделенного подмножества с наименьшим индексом n, а конечный номер

присваивают столбцу из выделенного подмножества с наибольшим индексом n.If a subset of the elements of the array M ^k with matching estimates

as well as matching estimates

does not include the extreme columns (figure 5), then the starting number

assign the column from the selected subset with the smallest index n, and the final number

assigned to the column from the selected subset with the largest index n.

If the indicated subset includes extreme columns (Fig. 6), then the column with the lowest index n from the group of columns at the end of the array is considered the initial column, and the column with the highest index n from the group of selected columns at the beginning of the array is considered the final column. This designation corresponds to the circular azimuth (physical reality) clockwise, as shown in Fig.7. In Fig. 7, the number 1 * shows the position of the radar (the center of the circular scanning indicator), and the number 2 * indicates the direction of the azimuth.

в пределах k-го элемента разрешения по дальности (на k-й дальности r_k) с использованием нижеприведенных формул и правил:12) Calculate the true azimuthal position of VO

within the k-th range resolution element (at the k-th range r _k ) using the following formulas and rules:

in the absence of coincidence of estimates of the component velocities for the first and N _{overview of the} azimuthal positions (columns of the array M ^k )

in the presence of coincidence estimates of the component velocities for the 1st and Nth _{review of the} azimuthal positions

находится ВО.13) Make a decision that in the kth element of the range resolution in azimuth

is in.

, где V_r и V_τ - соответствующие этому ВО составляющие скорости.14) For all detected VOs, the linear velocity Vvo is calculated using the formula

, where V _r and V _τ are the corresponding velocity components of this VO.

15) Information on all detected HEs is displayed on the radar monitor in the form of lines, in each of which the azimuth, range, linear velocity, its radial and tangential components are indicated, and on the screen of the circular viewing indicator, points in space with azimuths and ranges of detected HE are marked with brightness marks .

The invention consists in the following.

With the coherent addition of radar signals, the magnitude of the resulting vector (sum) depends on the degree of correspondence (equality) of the phases of the terms. Since VO, which is a source of reflected signals, during the accumulation interval T _n changes its orientation and range according to a complex law, which is taken into account by expression (1), it is impossible to predict or reveal this law, since the number I and the relative position of the RCs included in composition of HE. In addition, the exact values of the components of the velocity vector are unknown. All these factors and parameters are unique for each specific HE (they differ and are determined by the specifics of the situation). Well-known methods of measuring the spatial vector of linear velocity of HE and its components require a long time and do not provide high accuracy.

The best quality of coherent addition is ensured if the object of reflection of the radio waves is stationary. Then the phases of the signals reflected from it are the same and their in-phase addition becomes realizable. The presence of phase components associated with the movement of VO degrades or destroys the common mode. This means that in order to ensure the in-phase addition of reflections, it is necessary to eliminate phase incursions, the nature of which is due to the movement of the HE. The zeroing of phase incursions arising due to the presence of a radial or tangential component restores in phase and increases the amplitude of the coherent sum. Zeroing the indicated phase raids from the point of view of the physical nature hypothetically leads to a stop in the space, to stabilize its position.

Expression (1) describes a signal with amplitude and phase modulation caused by a change in time of the AT view and movement of the radar in the XAA space. In this case, the first factor (1) characterizes the envelope of the received signal packet in accordance with the XNA form, the second — the average Doppler frequency of the reflected signals, and the third — phase modulation due to the addition of reflections from different RCs of the illuminated VO surface at a certain angle. In addition, expression (1) shows that the phase component of the second factor, which depends on the radial velocity VO, includes only one unknown variable V _r . The rest are known a priori. The third factor (1) behaves more difficult over time. It depends not only on V _τ , but also on the mutual radial distances of the RC located on the illuminated surface of the airframe with a specific value of its spatial angle. However, it should be noted that the time of accumulation of signals from each object (determined by the duration of the radar contact of the main beam of the XAA with VO) T _n, in contrast to the prototype [3], is according to the method hundredths of a second. During this time, due to the rectilinear motion and trajectory yaw of the glider in the atmosphere, it will change its orientation relative to the radar by tenths of a degree, which leads to mutual changes in the ranges to the RC by tenths of centimeters. Such changes in the meter wavelength range cannot lead to significant changes in the total phase incursion. A change in the total phase incursion by units of degrees has virtually no effect on the result of coherent addition. The presence of the initial phase, which varies from period to period, is eliminated by conducting coordinated filtering using the reference local oscillation voltage of the corresponding sounding period. And the phase of wave reflection from the VO surface for all RCs is a constant value of π. Upon successful neutralization of the remaining phase fluctuations and incursions, the absence of information on the total phase shift φ _∑ does not affect the quality of coherent signal addition, i.e. the amplitude of the total signal, and is expressed only in the unknown, but quite specific value of the phase of the total signal, which is ignored by the proposed method.

. В этой функции неизвестной также является только одна переменная V_τ, если учесть, что обработка, согласно способу, ведется в пределах избранного k-го элемента разрешения по дальности, т.е. на k-й дальности r_k.Thus, we can assume that the third phase term of expression (1) can be replaced by a function of the form

. In this function, only one variable V _τ is also unknown, if we take into account that the processing, according to the method, is carried out within the selected k-th element of range resolution, i.e. at the k-th range r _k .

Therefore, when enumerating all the possible values of the radial and tangential components of the velocity vector of the object in the compensation phase expression of the form

with its complex term-by-term multiplication with the function of the received signal (1), in one of the cases the phase components in the resulting product will be zeroed, and the specified product will take the form

, выражение (21) можно заменить его приближенной формойAnd taking into account the significant excess of the average signal additive noise level expressed by the term

, expression (21) can be replaced by its approximate form

which shows the phase independence of the received signals from time, which creates the conditions for the addition of signals with a maximum degree of coherence, i.e. provides in-phase addition.

In other words, if the compensation is correct, the phases of all signals received from the main lobe of the XNA are aligned, and their complex sum will have a maximum amplitude. This fact is crucial in the proposed method.

A similar approach for organizing coherent signal addition is used in radars using the principle of inverse radar aperture synthesis [9-12]. Essentially, the proposed method is one of the variants of inverse synthesis of the aperture.

The above arguments and arguments are legal and do not require additional operations, if we are talking about HE, which do not include rotating elements of propulsion systems. However, such objects are not typical for surveillance (detection) radars, especially for military purposes and belonging to the air traffic control system. And when radio waves are reflected from the HE with open cavities of air intakes and rotor engines, TVE always arises, leading to high-frequency amplitude-phase modulation of the reflected signals [7]. In this case, in the structure of the received signal S ^k (t _n ) there will be additional phase components that vary in time according to a complex law. Their presence will violate the logic of compensation for phase shifts caused by specific values of the radial V _r and tangential V _τ components of the velocity VO. Therefore, the method provides for the compensation of high-frequency amplitude-phase modulation associated with the manifestation of fuel cells [13]. One way to compensate for such negative modulation in this case is to use an analog low-pass filter in the receiver after dividing the reflected signal into quadrature components. Another way to compensate for fuel cells is the use of digital smoothing methods for the implementation of reflection [13] in quadrature components. These methods can also be applied in the framework of the proposed method. Since all methods for compensating turboprop modulation are known, their nature is not disclosed.

Finally, dividing the entire space volume into range resolution elements and azimuthal directions β (t _n ) allows us to obtain estimates of V _r and V _τ for each impulse volume [14] of the space separately. And since the bursts of signals reflected by VOs amount to tens or hundreds of pulses, then for the impulse volumes adjacent in azimuth, the estimates of V _r and V _τ will be the same, which allows the VO detection to be made by comparing them. For pulsed volumes in which there are no VOs, the method will also provide estimates of V _r and V _τ . But their values will be random, and for the adjacent azimuthal positions of the XNA, these estimates will not coincide. It should be emphasized that the recommended method is operational precisely in the presence of typical noise in the channel for receiving radar information. The presence of noise causes a distortion of the estimates of V _r and V _τ at the edges of the main lobe of the XNA. As soon as the level of the useful signal becomes lower than the average noise level, the estimates of V _r and V _τ begin to be distorted, and their coincidence for adjacent azimuthal positions of the XNA within the range resolution element Δr ceases. Under ideal conditions (with an input signal-to-noise ratio of 80 dB and higher), the method does not provide detection in one view, and the measurement of the components V _r and V _τ requires the preliminary detection of all objects.

, где

- среднее квадратическое отклонение (СКО) оценки по максимуму правдоподобия доплеровской частоты сигнала; Т_н - время нахождения ВО в главном лепестке ХНА (время инверсного синтезирования апертуры).The accuracy of the estimation of the radial velocity VO V _r is determined by the known relation

where

- standard deviation (RMS) of the maximum likelihood estimate of the Doppler frequency of the signal; T _n - the time spent by the HE in the main lobe of the XNA (time of inverse synthesis of the aperture).

The accuracy of estimating the tangential velocity of HE can be determined by the method described in [3, 15, p.184-195]. In particular, the expression for the variance of the tangential velocity estimate has the form

where Z is the number of coherently added pulse signals.

The expression for the standard deviation of potential accuracy of the estimation of the tangential velocity V _τ has the form [3]

и

При времени обзора при Т_обз=30 с эти же характеристики составляют соответственно

и

Такие точности являются вполне приемлемыми для современных радиолокаторов обзора.On the basis of expressions can be shown that at t = 10 s _{actual situation review} via the present process can provide the MSE estimates the potential accuracy of the radial and tangential velocity components in the order

and

At a review time at T _review = 30 s, the same characteristics are, respectively

and

Such accuracy is perfectly acceptable for modern survey radars.

The positive technical effect of the proposed method is to enable the radars to detect airborne objects in the entire surrounding space in almost one review (one revolution of the antenna in azimuth) while simultaneously measuring the radial and tangential components of the velocity of each detected HE regardless of the presence or absence of its composition rotating structural elements of propulsion systems. The method can be used to select moving objects against the background of local objects, since the estimates of the components of speed belonging to local objects are zero or close to zero. By fixing this factor, signals from local objects can be excluded from processing. Unlike the prototype, the method evaluates the velocity components of any VO, i.e. approaching and moving away, as well as moving from left to right or from right to left relative to the line of sight. Moreover, the existing selection systems of moving objects with inter-period compensation [5, 6, 14] together with the signals of local objects suppress signals from objects moving tangentially. In radars using the proposed method, it is possible to select exclusively local objects and provide reliable detection of HE having only the tangential component of speed or both components of V _r and V _τ of the velocity vector.

The method can be recommended for implementation in survey radars of the meter and decimeter ranges used to control airspace in dual-purpose radar systems, that is, performing detection and measurement tasks in the interests of military and civilian ministries and departments. Such visibility radars are of particular importance in air traffic control systems and in the landing radar systems of the aerodrome services of the Ministry of Civil Aviation.

Information sources

1. Bakulev P.A. Radar systems. Textbook for high schools. - M .: Radio engineering, 2004, 320 p. (analogue).

2. Sosulin Yu.G. Theoretical Foundations of Radar and Radio Navigation: Textbook. manual for universities. - M.: Radio and Communications, 1992 .-- 304 p.

3. RF patent No. 2337378. IPC ⁷ G01S 13/42. The method of determining the parameters of the trajectory of the movement of air targets in the surveillance radar. Likhachev V.P., Mubarak N.Kh. Application No. 2007125110. Priority 2.07.2007. Publ. 10/27/2008. Bull. No. 30 (prototype).

4. Mitrofanov D.G. The study of the reflective characteristics of airborne objects in the conditions of manifestation of trajectory instabilities. // Proceedings of the Institute of Engineering Physics, 2009. No. 3 (13). S.37-46.

5. Radar devices (theory and construction principles). / Ed. V.V. Grigorina-Ryabova. - M .: Owls. Radio, 1970.680 s.

6. Theoretical foundations of radar. / Ed. J.D. Shirman. M .: Sov. Radio, 1970.560 s.

7. Radio-electronic systems: Fundamentals of construction and theory. Directory. / Ed. J.D. Shirman. M .: Radio engineering, 2007.512 s.

8. Nebabin V.G., Sergeev V.V. Methods and techniques of radar recognition. M .: Radio and communications, 1984. 152 p.

9. Steinberg B.D. The formation of the radar image of the aircraft in the microwave range. // TIIER, 1988. No. 12. T.76. S.26-46.

10. Mitrofanov D.G. A comprehensive adaptive method for constructing radar images in dual-purpose control systems. // Theory and control systems. Proceedings of the Russian Academy of Sciences, 2006. No. 1. p. 101-118.

11. Mitrofanov D.G. The formation of a two-dimensional radar image of the target with trajectory flight instabilities. Radio engineering and electronics. RAS, 2002. No. 7. p. 852-859.

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

13. Mitrofanov D.G., Prokhorkin A.G. Compensation methods for the influence of the components of the turbine effect when constructing images of aerial targets. // Radio engineering, 2006. No. 9. p. 32-37.

14. Finkelstein M.I. Basics of radar. - M.: Radio and Communications, 1983. 536 p.

15. Grishin Yu.P., Ipatov V.P., Kazarinov Yu.M. and other radio engineering systems. 1990 .-- 496 p.

Claims (1)

A method for determining the motion parameters of airborne objects in surveillance radars by using the coherent properties of the reflected signals, which consists in the fact that probing signals are emitted during the space survey, receive reflected signals, register the quadrature components of the reflected signals of each repetition period, calculate their complex shape and record these values in random access memory, form a matrix of reference signals, and each matrix of reference signals includes by P × L elements, the resulting signal matrix is formed, the elements of which are calculated as the sum of the products of the elements of the reference signal matrices and the corresponding reflected signals received during the review; among the elements of the resulting signal matrix, the row and column numbers to which the element with the maximum modular value corresponds are calculated linear velocity of an air object V _VO according to the rule of finding the hypotenuse of a right triangle, whose legs are radial and tangential speed components, characterized in that the number of pulses G received from one azimuthal direction by the main lobe of the directivity characteristics of the radar antenna is calculated in advance according to the formula

where int2 {·} is the symbol of the rounding operation to the nearest even integer; T _obz - the period of viewing the space in azimuth; Δθ _β is the width of the main lobe of the directivity of the radar antenna in azimuth; T _and - the repetition period of the probe pulses, the radiation of the probes and the reception of the reflected signals is carried out in the azimuthal range, starting from the azimuth (-Δθ _β / 2) and ending after one full revolution of the antenna in azimuth with the azimuthal position (2π + Δθ _β / 2), and when receiving the reflected signals of each repetition period T _and in the random access memory, the value of the corresponding azimuth β (t _n ) of the antenna is recorded at time t _n , where the value of n varies within (-G / 2) ... (N _review + G / 2) where

- the number of pulses taken in one circular survey in azimuth; int {·} - a symbol for calculating the integer value of a number in curly brackets; each received signal is transmitted digitally through a low-pass filter with a passband of 0-300 Hz, during registration of the quadrature components of the reflected signals of each repetition period and calculation of their complex shape, the reflected signals of the n-th period are recorded in the data array corresponding to the n-th azimuthal position β (t _n ) and having K elements in the number of range resolution elements

, where r _b is the near detection boundary, r _d is the far detection boundary, Δr is the value of the range resolution element, as a result of which all received signals are marked, i.e., to each received signal

corresponds to the well-defined azimuthal position of the antenna β (t _n ) and the k-th range resolution element, which determines the range r _k = Δrk, combines the received signals corresponding to the same ranges into separate implementation arrays, each of which records the complex values of the reflected signals, obtained at different azimuthal positions, but at the same range, and the elements of each k-th implementation array

correspond to azimuthal positions varying from (-Δθ _β / 2) to (2π + Δθ _β / 2), for each k-th element of range resolution and the corresponding k-th implementation array, G matrices of reference signals are formed

, where the superscript indicates the kth range r _k , with each gth matrix of reference signals

includes P × L elements, where

,

,

,

, V _{τ max} is the maximum possible value of the tangential component V _{τ of the} speed of the air object, V _{r max} is the maximum possible value of the radial component V _{r of the} speed of the air object, ΔV _r and ΔV _τ are the sampling steps of the radial values selected by the calculation

and tangential

components of the linear velocity of an air object, respectively, l is the current number for discrete selection

; p - current number for discrete selection

, for each element with number n from 1 to N, the _{overview of} each k-th implementation array forms the corresponding n-th matrix of the resulting signals

the values of the elements of the nth matrix of the resulting signals

calculated by the formula

among the elements of each n-th matrix of the resulting signals

determine the line number

and column

which corresponds to the element with the maximum modular value within the corresponding matrix of the resulting signals

using established numbers

and

calculate the radial and tangential components of the speed of airborne objects that are in space elements with a range of r _k and azimuth β (t _n ), according to the formulas

and

write the estimates of the radial and tangential components of the velocity of each k-th range resolution element in a three-dimensional array M ^k , in the first line of which the number n is placed, in the second - the corresponding estimates of the radial velocity, in the third - the corresponding estimates of the tangential velocity, within each k- of the first array M ^k , column elements are compared with adjacent numbers, and if there are two or more consecutive columns with the same values

, as well as matching values

fix the initial

and final

numbers for which the same estimates of the velocity components in the kth range resolution element are obtained, where the index “m” denotes the number of a private subset of elements with the same estimates of the velocity components, while the last and first columns of the array M ^{k are} also considered adjacent if the subset of elements array M ^k with matching estimates

, as well as matching estimates

does not include the extreme, that is, the first and last columns, then the starting number

assign the column from the subset with the smallest index n, and the final number

- the column from the subset with the largest index n, if the selected subset includes the extreme columns, then the initial column

consider the column with the lowest index n from the group of columns at the end of the array, and consider the column with the highest index n from the group of selected columns at the beginning of the array to be the final, calculate the true azimuthal position of the air object

within the k-th element of range resolution using the formulas and rules below:
in the absence of coincidence of the estimates of the component velocities for the first and N _overview columns of the array M ^k

;
if there are coincidence estimates of the component velocities for the first and N _overview columns of the array M ^k

where ω _obz - the angular velocity of rotation of the antenna when viewing space, decide that in the k-th element of the resolution in range in azimuth

there is an air object, for each m-th of the detected air objects at the k-th range, the linear velocity is calculated

according to the rule of finding the hypotenuse of a right triangle, whose legs are the corresponding radial and tangential components of speed, information on all detected air objects is displayed on the radar monitor in the form of lines, in each of which the azimuth, range, linear speed, its radial and tangential components for the corresponding aerial object, and the elements of range and azimuthal positions corresponding to the detected objects are marked on the indicator of all-round visibility p diolokatora review luminance marks.

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