RU2692912C1 - Method for simultaneous measurement of range, speed and acceleration of low-speed maneuvering air target in pulse-doppler radar stations with high frequency of repetition of pulses and linear frequency modulation - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention relates to a method for simultaneous measurement of range, speed and acceleration of a low-speed maneuvering air target (AT) in pulse-Doppler radar stations (RLS ID) with high frequency (HF) pulse repetition frequency and linear frequency modulation (LFM) in a RLS ID intended for detection, measurement of primary radar trajectory parameters (PRTP). Detection/measurement of PRTP is carried out based on three packs of probing pulses (PPP) from the chiral coupler. Determination of radial acceleration is carried out by estimating asymmetry of deviations of FPD relative to PPP on the first burst, which is determined during measurement. Velocity is determined from FPD at second and third PPP. Unambiguous determination of range is carried out based on the difference between the FPD measurements on the second and third PPP and using the doubled modulus of symmetrical increments of the chirp of these packs relative to the first PPP and procedures for evaluation/compensation of dynamic errors occurring during measurements.

EFFECT: technical result consists in improvement of information content of measurements and possibility of implementation in standard radar station RLS ID.

1 cl

Description

The invention relates to radar air targets (CC) and is applicable in stationary and mobile pulse-Doppler (ID) radar stations (radar) for military and civil purposes:

- operating in the modes with high (VCHP) pulse repetition frequency (PRF), low duty cycle and intra-pulse linear frequency modulation of the carrier frequency (chirp);

- intended for detection, measurement of primary radar parameters (RLP) and tracking CC;

in a wide range of velocities of approach to the radar, including radial velocities close to zero;

with intensive maneuvering of the CC and / or radar carrier, including the use of special ("anti-radar") tactical techniques (flight of an aircraft (LA) at extremely low / low altitudes, a sharp change in speed / direction of movement, "hovering", etc.);

with a small effective area of scattering (EPR) targets.

For existing radar ID models, at present, [7] are considered typical low-flying low-speed maneuvering targets with low EPR, for example, unmanned aircraft, including and possessing supermaneuverability properties. At the same time, such low-speed maneuvering CC for radar IDs are problematic from the point of view of their detection and measurement of RLP, which is due to the following circumstances.

Detection of CC with small EPR and at large distances (with close to unity “signal-to-noise” relations) and with a wide range of possible radial velocities requires an increase in the coherent accumulation time of the CC signal (up to hundreds of milliseconds) and the use of ICP to uniquely determine the velocities, in general, leads:

- to an increase in the number of “blind” zones in range (due to receiver blanking for the duration of the pulse emitting), the degree of ambiguity in measuring the range — the intraperiod position (delay) of the target signal (HCV);

- an increase in the total duration of radio contact with the EC due to the need to emit a series of probe pulse bursts (FDIs) to uncover “blind” zones when HCV ambiguity is detected and eliminated, as well as due to an increase in the duration of the FZIs themselves to achieve a coherent accumulation effect.

Typical for modern radar IDs are multipurpose tasks of tracking CC with long extrapolation intervals of trajectories. At the same time, the requirements for accuracy of PRLP measurements are becoming more stringent, and in conditions of intensive maneuvering, it becomes necessary to increase the information content of a radar measurement session — first of all, in terms of determining the derived spatial and angular coordinates of the second and higher order in order to ensure the accuracy and stability of tracking the maneuvering EC.

On the other hand, the radial acceleration arising during maneuver leads to a change in the characteristics of the received signal — the appearance of secondary frequency modulation; “Blurring” the EC signal spectrum and reducing the effect of coherent accumulation; reducing the signal-to-noise ratio at the detector input; the possibility of the manifestation of a single target signal in several Doppler filters, etc. In general, with a relatively long radio contact with the EC and with intensive maneuvering, radial acceleration significantly affects the capabilities of the radar ID for detecting the CC and for measuring the accuracy of its RLP.

In addition, for low-speed targets or during maneuvers of high-speed aircraft, leading to low speed of convergence or “freezing” (hereinafter, such CC, generally referred to as low-speed ones), additional difficulties arise in detecting / measuring RLPs. First of all, they are related to the EC Doppler signal - Doppler frequency offset (RMS), due to radial velocity - entering the spectrum of powerful interfering reflections from the ground (MO), i.e. in the "blind" zone on the Doppler frequency.

Thus, for the ID of the radar with VCHP when working on a low-speed maneuvering EC with a small EPR, it is currently important to solve the following problems:

- enable the detection of VTs / measurements of RSPL with a wide range of MO and low radial velocity;

- expanding the information content of the measurement session of the RLP at radio contact, including measuring the radial acceleration, and ensuring a sufficiently high accuracy of measuring the RLP under the conditions of intensive maneuvering required to ensure accurate sustained tracking of the EC at relatively long trajectories extrapolation intervals.

In the radar-ID, traditionally, along with the measurement of the angular coordinates, the RLP measurement session within the framework of the radio contact with the CC is limited to measuring the range and radial velocity. Expanding the functionality of the radar ID as an information-measuring system due to the inclusion of radial acceleration in the composition of the measured RLP in conditions of intensive maneuvering is almost mandatory:

- to take into account / compensate for the effect of acceleration on the characteristics of the received signal and to ensure coherence conditions in the conditions of maneuver (during the initial signal processing);

- to account for / compensate for dynamic errors in the RLPP estimates, which are formed in maneuver conditions at a relatively long radio contact with the CC, including the FDI series;

- to adapt the parameters of the tracking filters in the tracking loop, to perform a more accurate extrapolation of the trajectories at relatively long intervals, i.e. to ensure accurate and sustainable tracking of intensively maneuvering targets (during secondary processing of information).

Known [1-3] and widely used in VCh methods of detecting CC, allowing to reveal the "blind zone" in range by radiation of a series of FPI with different values of the CRP. When searching / detecting a VC, FDI series usually include “smooth” packs that are formed without the use of a special intra-pulse chirp. In such cases, simultaneously with the detection of the VC, the ambiguous range (HCV) is measured, the Doppler shift of the reflected frequency and the radial velocity is estimated. However, at small values of the radial velocity, when the DSCH hits the spectral zone of powerful MOs, the task of detecting / measuring the RLP in some cases is practically impossible to solve, which is a significant drawback that limits the radar ID functionality when working with low-speed CC.

The number of known methods for determining the distance to the detected CC in the VCHP and average (SSP) modes of the PRF [US 471 3664 A, publication date (dp) 12.15.87; EP 0490423 A, p. 06/17/92; RU 2010244 C1, d. 03/30/94; FR 2709835 A, p. 03/17/95; US 5546088 A, d. 13.06.96; US 5905458, DP 11/19/97; RU 2145092 C1, dp 01.27.2000; RU 98104808 A, dp 01.27.2000; EP 1043601 A1, D.S. 10/11/2000; WO 020633336 A1, e. August 15, 2002; RU 2237265 C1, d.p. May 27, 2003; RU 2206102, p. 06/10/2003; RU 2221258 C1, DP 01.10.2004, RU 2237265, p. September 27, 2004, RU 2296346, p. P. 27.03.2007, etc.].

In the general case, for the ranging measurements of the detected VTs, in the indicated methods, measurements of the time and / or frequency X-ray parameters of the received signal are used: DFC - with “smooth” FDI and rangefinder frequency (MFR), shifted by DFM in FDI. Methods that use only measurements of HVAC require radiation of a relatively long series of FDI with different values of the PRF. This ensures a relatively high accuracy of ranging (at the level of tonnage of HCV measurements). Methods based only on frequency measurements — measurements of the DFC and DMC — after detection require additional emission of only one or two FPIs with chirp, but the accuracy of ranging is relatively low (with errors from hundreds of meters to several kilometers). Combined methods based on frequency and time measurements, in general, allow, based on range estimates obtained by chirp methods, to significantly reduce the time to eliminate the uncertainty of HCV measurement by varying the CRPD and, as a result, ensure the accuracy of determining the range at the error rate of the HCV . To eliminate the ambiguity of the PIT, it is also possible to use not the variations of the PRF, but the statistical processing of the measurement samples of the unambiguous (with the LFM) and ambiguous range obtained in a series of packs with a constant PRF. For example, in the range meter based on chirp [RU 2237265, 09/27/2004], statistical “smoothing” of the growing sample of HVAC measurements and a single-digit range determined in the traditional way with chirp [1] is used. However, to achieve the required accuracy, a relatively long time is also needed for the formation of a statistical sample of measurements.

When using these methods, with the exception of [RU 2221258 C1, RU 2296346], it is assumed that the CC is detected by the echo signals of “smooth” FDI, which means a rather high radial velocity and finding the DMS outside the MO spectrum.

In the methods [RU 2221258 C1, RU 2296346] used in the PTS, it is assumed that VC search and detection and range measurement is carried out only on the basis of FDI with chirp, which creates a potential opportunity to detect / measure parameters of a low-speed VC whose signal is displaced by the chirp , can be observed outside the "blind" zone in frequency.

As a prototype of the invention in terms of sequencing and the steepness values of packs with chirp in the RLP detection / measurement session and range determination procedures, a method of measuring the distance is considered [RU 2221258 S1], which involves the following actions in the radar ID for CAS.

1. Search / detection and measurement of HVAC and the rangefinder frequency of the detected target is carried out with the emission of FPIs at the SPE with a given slope of the chirp So.

2. With the same PRF, as in position 1, two more FZIs with values S ₁ and S ₂ of the chirp steepness are consistently emitted, moreover: the value of the steepness So is the average between the values of S ₁ and S ₂ , and the increments of the slope equal in magnitude , have different signs, i.e .:

The values of the slope increments are chosen such that the total offset does not exceed the values of the PRF minus the length of the “blind” zone in frequency, even for those CCs that are at the maximum distance, i.e.

where: F _p - average CPI; ΔF _sz - the width of the "blind" zone by the Doppler frequency.

When the chirp slope changes, the CC signal detection and measurement occurs in the same range channels as position 1.

3. With memorized frequency measurements (DMF) performed in position 1, and at least one frequency measurement in position 2, the frequency increments of the received signal occurring due to the chirp steepness increment of this signal are calculated by single-valued, but coarse ranges. Then, on the basis of the data obtained and using the measurement of the HCV, an exact single-digit range is calculated.

The method of measuring the range in the radar ID [RU 2296346], considered as an analogue of the invention, differs from the prototype method in that at the first stage the initial value of the slope So is calculated a priori, based on providing a “rough” distance measurement for all VC within the radar range . In addition, the required value of the slope S _{1 is} calculated for the next pack. Based on the obtained unambiguous range of chirp, then a new value of the SIP is calculated (for the next pack, radiated from the required S ₂ slope of the chirp), ensuring that signals enter the zone of transparency in range. The reflected signals of this pack, similar to the prototype method, determine for each VC a unique range from the chirp signals, measure the HCV (ambiguous delay), calculate the TLI number and determine the final corrected value of the VPS using the measurement of VPC. In this method, from the point of view of the sequence of radiated packets with chirp in a session of detection / measurement of radar parameters of the CC, it is also possible that the modulus of the equal-valued increments of the chirp steepness, i.e. satisfying the conditions (1) and (2) of the prototype method [RU 2221258 C1].

The disadvantages of the prototype method and analogue of the invention include:

- insufficient for the modes of ICP, the accuracy of determining the range of signals from the chirp, limiting the possibility of their use only in FIR modes (with relatively large distances corresponding to the duration of the TFI) and does not allow to eliminate the uncertainty of TFI at HFI (with TFI, corresponding distances of about 1000 m and less ).

- a significant deterioration in the accuracy of chirp-ranging when intensive maneuvering, in comparison with the accuracy achievable with the stationary nature of the movement "VTs-RLS";

- low information content of the measurement session RLP, because there is no possibility of measuring the radial velocity, as well as the acceleration, the assessment of which is required in conditions of intensive maneuvering.

There is a method of simultaneously measuring the range and radial velocity only by signals from the chirp. In the radar device with continuous radiation and chirp, providing measurement of the distance and speed of the target [application 198335199 from 07.25.98, Germany, IPC ⁶ G01S 13/34 / WeiRG, Daimler-BenzAerospaceAG, p. 11.02.99] a patented scheme with continuous radiation and symmetric (increasing and decreasing) chirp, containing separate receiver and transmitter antennas, from which a signal is provided to the receiver through a directional coupler that provides a difference frequency in the mixer. The receiver contains in-phase and quadrature channels, from the outputs of which the signals are sent to the ADC. When processing using digital filters and building the autocorrelation function, the components characterizing the range are singled out in the form of half-sum difference frequencies for the sections of the modulation characteristic corresponding to an increase and decrease in the carrier frequency. Based on the frequency difference is determined by the component of the velocity of the target, characterized by the RMS.

In terms of the procedures for simultaneous determination of the range and speed based only on chirp signals, this device is also considered to be analogous to the invention.

The disadvantages of this analogue include:

- the impossibility of application in the radar ID, as it is assumed RL device with continuous radiation;

- restriction on the application only in cases where it is possible to implement a symmetric increase and decrease in the chirp (with equal modulus and different signs of the chirp steepness);

- insufficient information content of the measurement session RLP for intensive maneuvering conditions, because there is no possibility of measuring the radial acceleration.

Traditionally, acceleration is calculated by numerical differentiation of the speed observed during several radio contacts (review periods). The beginning of the maneuver and the presence of acceleration are detected on the basis of the calculation of the statistical characteristics of deviations of the real and predicted parameters of the EC motion, which requires obtaining measurements during several periods of the review. For example, there is a known method of detecting a CC maneuver based on an analysis of the updating sequence [8] during secondary information processing, in which this sequence is processed by a set of low-pass filters tuned to a certain type of CC maneuver. There are a number of ways to determine the beginning of the EC maneuver on the basis of information about acceleration, the use of which, however, requires the use of additional sensors, for example, as part of an AC-radar tracking system CC. These include, for example, the method of adapting the tracking system of a maneuverable VC in range based on information from meters of different physical nature [patent RU 2303797 / IPC G01S 13/87].

A known group of methods, for example, presented in the patents [RU 2282873, p. 08.27.06, RU 2542347, p. 02.20.2015, RU 2154837, d.p. 08.20.2000 et al.] And [5, 6, 9, 10], suggesting detection of the EC maneuver directly at the stage of primary signal processing. These methods require a significant modification of multi-channel signal processing devices in range and speed in order to increase the filtering efficiency of signals with a non-linear change in the Doppler phase caused by the acceleration of the target. As a technical solution, it is usually proposed to introduce multichannel acceleration with the definition of the channels most relevant to the received target signals, by mutual comparison and selection of the maximum signals at the outputs of these channels. For example, in the well-known method [10], after the ADC, a panoramic scan of the signal with respect to the frequency and the derivative of the frequency is carried out, followed by accumulation in the matrix filter. In another method [RU 2154837], the signal sample is divided into a series of short samples, the calculation of the correlation sums in the grid nodes of the hexagonal type. In the methods of joint measurement of the radial velocity and radial acceleration [9], the correlation sums of the signal sample and the reference complex chirp signals are calculated, and the maximum of the correlation sum module over the rectangular grid nodes is determined.

In the phase difference method [5] of the measurement of acceleration, the signal is transferred to the video frequency region, divided into two signals with a duration equal to half the time of the radio contact. One of the signals is complexly mated and, then, both signals are multiplied. The Fourier transform is performed and the position (displacement) of the maximum proportional to the acceleration is estimated and the acceleration is determined. This method is considered as an analogue of the invention in terms of determining the radial acceleration based on the evaluation of the steepness of the secondary chirp signal of the target due to the acceleration.

The disadvantages of the above methods associated with the determination of radial acceleration during primary signal processing, including and method [5], include:

- the need for substantial modification of the systems of primary signal processing for the practical implementation of these methods in the radar ID and significant computational costs that impede their implementation in real time;

- the difficulty of implementation for wide ranges of measured parameters of frequency and frequency derivative (due to a sharp increase in the required signal processing channels);

- relatively low accuracy of determining the acceleration for small values of the signal-to-noise ratio due to the occurrence of anomalous errors and with a small duration of radio contact.

In General, given the noted disadvantages of the above analogues and prototype of the invention, the main objectives of the invention are the following.

1. Expansion of the functionality of the prototype on the informativeness of the RLP measurement session detected by a maneuvering low-speed CC by providing simultaneous measurements of the range, radial velocity and acceleration within the same radio contact with the CC and with the same number of FPIs used in the RLP measurement session

2. A significant increase in the accuracy of determining the distance to the EC with uniform movement (by expanding the ranges of variation of the steepness used in estimating the range) and during intensive maneuvering (by estimating and compensating for the effect of proximity dynamics during radio contact using radial acceleration measurements).

3. A significant increase in the accuracy of determining the radial velocity (in comparison with the known method of measuring speed only from signals with chirp) under conditions of intense maneuvering - based on the compensation of dynamic errors during radio contact taking into account measurements of radial acceleration.

4. Ensuring the practical implementation of the claimed method of simultaneous measurement of range, speed and acceleration without changing the typical structure of the primary signal processing used in existing samples of radar ID with HFD.

The solution of the above problems 1-4, in essence, is the technical effect of the invention, which in the present method of simultaneously measuring the range, speed and acceleration of a low-speed maneuvering CC in the radar ID at a high pulse repetition rate and chirp is achieved by performing the following actions.

1. By analogy with the prototype, emit three bundles of probe pulses of FDI (1), i = 0, 1, 2 with given values of the slope S ₀ , S ₁ , S ₂ (S ₀ is average relative to S ₁ and S ₂ , and increments the slopes of S ₁ and S ₂ relative to S ₀ have a different sign) and based on the processing of the echo signals of these packs, the values of the AED τ _i and the HFM F _ia (i = 0, 1, 2) are measured and memorized for the detected VTs.

2. Unlike the prototype, all FPIs emit at a high repetition rate F _p , and the stored frequency and time measurements obtained by known methods τ _i and F _ia (i = 0, 1, 2) are processed as follows:

- determine the deviations of the measured values of the DMC, obtained by the second and third pack from the DMC, determined by the first pack (hereinafter referred to as tex - base DMC):

and the sum of these deviations:

- based on measurements of the HCV τ ₀ and τ ₂ , obtained by the first and third packs, determine the average offset value of the HCV for the known and constant time T of the _pack between the nearest moments of radiation of FDI:

- using the calculated values of the sum of deviations of the measured MST from the base frequency and the average offset of the HCV, with known values of S ₁ , S ₂ given the slope of the chirp, time interval T of the _pack between FDI and known wavelength λ determine the value of the slope S _a for chirp, due to radial acceleration , and also value and _{c of} this acceleration:

- using measurements of DMP F _ia (i = 1, 2) obtained by the second and third packs, the calculated average offset of the HCV Δτ _sr for the known and constant time T of the _pack between the nearest packs, the known values of the given slope S ₁ and S ₂ for the second and the third pack, as well as the measured value of the steepness S _a chirp due to acceleration determine:

Doppler frequency F _∂2 and radial velocity V _c at the moment of radiation of the third bundle:

R ₂ range to VTS at the time of the third bundle radiation:

and then, using the calculated value of the distance R2, with a known pulse repetition frequency F _n = 1 / T _p and with the third ambiguous delay τ ₃₂ measured by the signals, calculate the corresponding period number of the pulse repetition and determine the updated value of the distance R at the moment of radiation of the third FDI by known formulas:

where: int {•} is the procedure of taking the integer part of the number enclosed in brackets.

The physical essence of the method is based on the following provisions.

It is known [4-6] that radial acceleration leads to a secondary Doppler effect - a quadratic “phase advance” and the appearance of a target after the chirp transformation in the echo signal. When FDI with a given index K (steepness), the chirp signal at the input of the receiver C _prm (t) has the form:

А - амплитуда сигнала; Р - импульсная мощность; λ - длина волны; f₀ - несущая частота; С₀ - амплитуда зондирующего сигнала; G - коэффициент усиления антенны; К - заданный индекс ЛЧМ в ПЗИ; σ_ц, V_ц, а_ц - ЭПР, скорость и ускорение сближения с ВЦ, соответственно; с - скорость распространения радиоволн; t -время; ξ(t) - шум в приемном канале. Компоненты в этом выражении характеризуют:

- эффект Доплера, обусловленный радиальной скоростью;

- ЛЧМ при заданном в ПЗИ индексе модуляции;

- вторичную ЛЧМ, вызванную ускорением, причем индекс К_а этой дополнительной ЛЧМ пропорционален значению радиального ускорения

т.е. компонента

а результирующая ЛЧМ, обусловленная заданным индексом К и индексом К_а по ускорению характеризуется как

Where:

A is the signal amplitude; P is the pulse power; λ is the wavelength; f ₀ - carrier frequency; С ₀ - amplitude of the probing signal; G is the antenna gain; K - given chirp index in FDI; σ _c , V _c , and _c - ESR, speed and acceleration of approach with CC, respectively; c is the propagation velocity of radio waves; t is the time; ξ (t) is the noise in the receiving channel. Components in this expression characterize:

- Doppler effect due to radial velocity;

- chirp with modulation index specified in the FPI;

- secondary chirp caused by acceleration, and the index K _and this extra chirp is proportional to the radial acceleration

those. component

and the resulting chirp, due to a given index K and index K _and is characterized by acceleration as

For a given chirp in FDI, the frequency f of the emitted signal is: f (t) = f _o + K t, K ≠ 0, and the frequency f * of the echo signal is such PZI: f * = f ₀ + f _d + K (t-T _s ), where: T _s = (2 / c) R - delay signal proportional to the distance R to the CC; F _d = 2V _c / λ - DSCH, due to the speed V _c convergence.

The measurement is available the difference between the frequencies of the emitted and received signal - the ranging frequency, depending on the RMS and unambiguous delay of the signal: F = f * -f = F _d -CT ₃ = F _d + ST _h .

Note:

A positive modulation index leads to a decrease in the ranging frequency relative to the Doppler frequency and vice versa. Further, the term “S modulation slope” is used in the sense of S = -K. A positive slope S> 0 corresponds to a positive increment of the ranging frequency relative to the Doppler frequency and vice versa.

Applied to a sequence of three FPIs with chirp P _i (i = 0, 1, 2), radiated with given values of the slope S ₀ , S ₁ and S ₂ , corresponding to conditions (1) and (2) by analogy with the method of the prototype, The measurement is available DMP F ₀ , F ₁ and F ₂ . Due to the "symmetry" of the values of the slope S ₁ and S ₂ relative to S ₀ in the absence of acceleration (F _{d i} = const), the deviation of the DMF F ₁ , F ₂ from the initial (base) frequency F ₀ will also be close to symmetry (relative to the base frequency). The deviation moduli of the MFDs differ only by small values, depending on the values of the steepness and the difference of the distances to the EC at different points in the emission of FDI. For low-speed CC, the change in the distance over the time between the moments of emission of the FDI can be considered insignificant.

For example, in the absence of acceleration:

- values of MDC:

- deviation of MFR from base frequency:

,

,

- ДСЧ при постоянной радиальной скорости.where: T _s0 , Δτ _0/1 , Δτ _0/2 is the delay corresponding to the distance at the moment of emission of FDI P ₀ , offset of HVAC during the time between the emissions of FDI P ₀ and P ₁ , P ₀ and P ₂ , respectively;

- DSCH at a constant radial velocity.

- amount of deviations:

.The criterion for the absence of acceleration is the relative symmetry of the MST, which is expressed by the equality

.

In the presence of acceleration due to secondary modulation, the relative symmetry is broken. For example, with a uniformly accelerated motion during a radio contact:

,- values of MDC:

,

where: F _ia - DMC at a given chirp in FDI P _i and the presence of acceleration; F _di - DSCH due to the speed of convergence for FDI P _i ; S _a is the steepness of the chirp at uniformly accelerated motion;

where: T _burst is the interval between the moments of radiation of FDI, which is considered to be the same and, at least, equal to the duration of FDI.

- deviation of MFR from base frequency:

amount of deviations:

whence it follows that the steepness S _a chirp due to radial acceleration and the value of the acceleration a _{c are} determined by the expressions:

- определяется на основании доступных частотных измерений F_ia по всем ПЗИ П_i; Δτ_0/i=τ₀-τ_i - определяется на основании доступных измерений ВПЦ τ_i по всем ПЗИ; S_i, λ, Т_пачки - известные величины.for which:

- determined on the basis of available frequency measurements F _ia for all FDI P _i ; Δτ _{0 / i} = τ ₀ -τ _i - is determined on the basis of available HCV τ _i measurements for all FDI; S _i , λ, T _packs - known values.

Thus, in the invention, the essence of the measurement of acceleration is:

в выявлении относительной асимметрии («перекоса») измерений двух ДМЧ (относительно принятой базовой ДМЧ), возникающей при наличии радиального ускорения из-за дополнительной ЛЧМ в принимаемом сигнале, а также трендом радиальной скорости и смещением ВПЦ в течение радиоконтакта при измерении.

in identifying the relative asymmetry (“skew”) of measurements of two DMCs (relative to the adopted basic DMCs), which occurs when there is radial acceleration due to the additional chirp in the received signal, as well as the trend of the radial velocity and offset of the HVAC during the radio contact during the measurement.

в оценивании на основе частотных и временных измерений по эхо-сигналам трех ПЗИ значения крутизны дополнительной ЛЧМ, вызванной ускорением, и значения этого ускорения.

in the estimation based on the frequency and time measurements from the echo signals of three FDIs, the values of the slope of the additional chirp caused by the acceleration and the values of this acceleration.

In the general case, the presence of measurements of the MST by the echo signals of two FPIs with different specified chamfer slopes allows determining both the distance to the CC and radial velocity.

In the prototype method, the determination of the range is carried out by the increment of the Doppler frequency of the received signal, which occurs due to a known increment of the steepness of the received chirp signal (relative to the slope of the first pack with chirp). In this case, unambiguous, but relatively coarse estimates of the range are calculated, the accuracy of which, in particular, depends on the value of the slope increment used in the calculation. Unlike the prototype, to improve the accuracy of ranging on the signals from the chirp, in the claimed invention:

используются измерения двух ДМЧ, выполненных по второй и третьей ПЗИ с различными по знаку приращениями крутизны (относительно базовой ДМЧ), что эквивалентно по модулю удвоенному приращению крутизны (с сравнении с приращением, используемым в прототипе), которое затем и применяется при определении дальности, обеспечивая повышение точности вдвое;

measurements are used of two DFMs made on the second and third FDIs with increments of different steepness (relative to the basic DSTs), which is equivalent to the modulus of twice the increment of steepness (compared to the increment used in the prototype), which is then used to determine the range, providing double the accuracy;

используется более широкий диапазон относительных приращений крутизны, отвечающих условию (2) при ВЧП (в сравнении с режимом СЧП);

a wider range of relative steepness increments is used that meet condition (2) for HFC (compared to the SPP mode);

при определении дальности, используя измеренное значение дополнительной крутизны ЛЧМ из-за ускорения, учитываются и компенсируются эффекты ускорения (влияние дополнительной ЛЧМ, «дрейф» доплеровской частоты (скорости) и ВПЦ на интервалах между ПЗИ), что приводит к существенному повышению точности определения дальности в условиях интенсивного маневрирования (в сравнении с прототипом).

when determining the range, using the measured value of the additional chirp of the chirp because of acceleration, the effects of acceleration are taken into account and compensated (the effect of the additional chirp, “drift” of the Doppler frequency (speed) and HVF on the intervals between the FDI), which leads to a significant increase in the accuracy of determining the range in conditions of intensive maneuvering (in comparison with the prototype).

With simultaneous determination of the range / speed in the analogue [Application 198335199, Germany, IPC ⁶ G01S 13/34 of 11.02 99], the Doppler frequency (speed) is formed based on the difference of two frequencies measured by signals from a symmetric (differing only in sign) set Chirp with continuous radiation. Unlike analogue, in the claimed invention:

обеспечивается инвариантное по отношению к ДСЧ определение скорости только по измерениям ДМЧ, выполненных при ВЧП по двум ПЗИ, в общем случае, при любых неравных друг другу значениях крутизны их ЛЧМ, а в конкретном случае - для значений, симметричных относительно крутизны в первой пачке с ЛЧМ и имеющих одинаковый знак крутизны;

the speed is invariant with respect to the DSS and is determined only by measurements of the DFMs performed during the HF of two FDIs, in the general case, for any values of their chirp steepness that are unequal to each other, and in a particular case for values that are symmetric with respect to the slope in the first pack with chirp and having the same slope sign;

при определении скорости также учитываются и компенсируются эффекты из-за ускорения (ЛЧМ из-за ускорения, «дрейф» скорости) и смещение ВПЦ на интервалах между ПЗИ в течение радиоконтакта), что приводит к повышению точности определения скорости в условиях интенсивного маневрирования.

in determining the speed, effects due to acceleration (chirp due to acceleration, “drift” of speed) and displacement of HVAC at the intervals between FDI during radio contact are also taken into account and compensated, which leads to an increase in the accuracy of determining the speed under conditions of intensive maneuvering.

Analysis in increments and partial derivatives [11] for relations (3) - (7) of determining the chirp steepness due to the acceleration S _a and the acceleration a _c leads to the following expressions for absolute errors and standard deviations (without taking into account the implementation errors specified in the FDI LFM steepness, which for existing master oscillators are generally considered to be insignificant).

The absolute errors δ _{Sa of the} definition of the chirp steepness and δ _{and the} definition of the radial acceleration are:

where: δ _Fia - measurement error DMC; δ _τ is the measurement error of the ambiguous delay (HCV). Considering that T _packs can be hundreds of milliseconds, and the CC is low-speed, then the duration of T _packs >> Δτ _cf and in this case the expression is correct:

Accordingly, the MSE of errors for determining the slope σ _Sa and acceleration σ _a :

where: Δf - discrete frequency measurements (width Doppler filter), wherein the sampling error is set equal variance Δf ^2/12; σ ² _δτ is the variance of measurement errors of the HCV.

S₁=12 кГц/мс; S₂=4 кГц/мс; λ=3 см) и при радиальном ускорение 10g (при котором крутизна S_a≈6533 Гц/с), получаются значения СКО ошибок:For example, for typical parameters of radar IDs with HF (filter width Δf = 15 Hz; SD

S ₁ = 12 kHz / ms; S ₂ = 4 kHz / ms; λ = 3 cm) and with a radial acceleration of 10g (at which the slope S _a ≈6533 Hz / s), the values of standard deviation of errors are obtained:

при Т_пачки=100…300 мс, соответственно.

at T _packs = 100 ... 300 ms, respectively.

Note: The errors in determining the steepness and acceleration are most dependent on the measurement errors of the DMP, which, for large signal-to-noise ratios, are mainly instrumental in nature and depend on the width of the Doppler filter. In the least degree - from errors of measurement of HVAC, scaled by the steepness of chirp on acceleration. Measurement errors of the HCV, depending on the assigned values of the steepness, lead to errors not exceeding units of Hz / s, which is several times less than the errors caused by the sampling of frequency measurements.

For comparison: according to the results of mathematical modeling of the phase-difference method for measuring acceleration, considered as an analogue of the invention in terms of acceleration, with the comparable parameters of the radar ID [5], the average deviation of the radial acceleration determination errors is 1.6 ... 1.2 m / s ² with time radio contact with the EC 100 ... 300 ms, respectively.

Thus, the invention provides a measurement of radial acceleration with an accuracy exceeding the accuracy of the analog, with simple computational procedures in contrast to the analog that requires a much larger computational resource in the primary signal processing.

), фактически эквивалентный аналогу:

When using frequency measurements with symmetric chirp, as in the analogue [application 198335199 dated July 25, 1998], the ratios (8) - (10) for determining the DST, proposed in the invention (8) - (10) for determining the rapprochement during a radio contact, degenerate into the next particular case of HFC (with sign (S ₁ ) ≠ sign (S ₂ ),

), actually equivalent to the analogue:

In uniform motion and assuming that for the low-speed range VTS increment during the time between FDI considered insignificant (T _s2 = _P1 ≅T T _s), the estimation accuracy of the Doppler frequency shift from the expression (15) depends only on the frequency error measurement and the accuracy of range estimation according to expression (16) - from frequency measurement errors scaled by a double modulus of the assigned chirp slope.

измеряемые ДМЧ:In the case of uniformly accelerated motion, the RNP and range estimates obtained in this way, along with the indicated frequency measurement errors, will also have a dynamic error. For example, when S ₁ > 0, S ₂ <0,

measured dims:

Then the absolute error in estimating the DSSH:

where: Δ _Fdinam = -S _a (T _s -0.5 T _packs ) is an unaccounted dynamic error. For example, with a radial acceleration of 10g (S _a ≈6533 Hz / s), T- _packs = 100 ms, a range of 15 km (T _s = 0.0001 s), the dynamic component of the RMS estimation error is | Δ _Fdinam | ≈326 Hz, which is a wavelength of λ = 3 cm leads to a significant additional error in the radial velocity ≈4.9 m / s, ignored in the equivalent equivalent relation (15).

Similarly, for the equivalent analogue of relation (16), when determining the range, along with the component depending on frequency measurement errors and steepness, there is an unaccounted dynamic error in the estimate, which, for example, with a chirp slope S = 12 kHz / ms, will be ≈4083 m. Such an error practically excludes the possibility of using these estimates to eliminate ambiguity in range in the modes with HFC and low porosity.

Например, для ранее рассчитанного значения,

при дальности 15 км и Т_пачки=100 мс, значения СКО

что соответствует малым значением СКО некомпенсированной динамической ошибки по скорости ≈(4…10)*10^-3 м/с при λ=3 см.In the present method, the compensation of the dynamic error in the estimation of the DFS is carried out with the absolute error δ _{ΔF dyns} = (T _s -0.5 T _packs ) δ _Sa. Respectively, the error standard error compensation

For example, for a previously calculated value,

at a distance of 15 km and T _packs = 100 ms, the standard deviation values

which corresponds to a small value of the standard deviation of the uncompensated dynamic error in speed ≈ (4… 10) * 10 ^-3 m / s at λ = 3 cm.

Similarly, with a symmetrical slope of ± 12 kHz / ms, the standard deviation of the uncompensated dynamic error in the range estimate is ≈368 ... 119 m, which is more than an order of magnitude less than the dynamic error in range (≈4083 m) Hz introduced in the range estimate by the relation (16) equivalent to the considered analogue [application 198335199 of July 25, 1998] of the invention.

, где

- СКО ошибок измерения отклонения дальномерных частот. При больших отношениях «сигнал/шум» ошибки частотных измерений δ_F, в основном, зависят от ширины Δf доплеровских фильтров и характеризуются дисперсией D_F=Δf²/12. При аналогичных условиях в заявляемом способе оценка дальности сводится к выражению вида R=(с/2) [ΔF/2ΔS] с использованием отклонений частоты, фактически вызванных удвоенным приращением крутизны |ΔS*|=|ΔS₁₂|=|S₁-S₂|=2|ΔS|. Как следствие, в сравнении с прототипом вдвое снижается значение СКО ошибок по дальности -

In the method of measuring the distance [RU 2221258 C1], adopted as a prototype, the range estimate with radio contact is performed by the ratio of the form: R = (s / 2) [ΔF / ΔS], where: ΔF is the frequency deviation (DMC) caused by the increment of the slope ΔS, and ΔS = ΔS ₀₁ = S ₀ -S ₁ or ΔS = ΔS ₀₂ = S ₀ -S ₂ . With a uniform approach and without taking into account the displacement of the HCV during the time between FDI (for low-speed VC), the potential accuracy of the prototype method is characterized by the MSE of range determination errors from the chirp signals

where

- RMS errors of measuring the deviation of the ranging frequencies. When large ratios "S / N" frequency measurement error δ _F, mainly depend on the width Δf of Doppler filters, and characterized by a dispersion D _F = Δf ^2/12. Under similar conditions in the claimed method, range estimation is reduced to an expression of the form R = (c / 2) [ΔF / 2ΔS] using frequency deviations actually caused by a double increase in the slope | ΔS * | = | ΔS ₁₂ | = | S ₁ -S ₂ | = 2 | ΔS |. As a result, in comparison with the prototype, the value of the mean-square error of the range error decreases by half.

In the case of uniformly accelerated motion, the range estimates obtained in accordance with the method of the prototype, along with the errors of frequency measurements, will also contain significant dynamic error. For example, even with a relatively small acceleration of 1g (i.e., with the steepness of the secondary chirping factor S _a ≈ 653 Hz / s), the uncompensated dynamic component of the range error | ΔR _dynamic | ≈ (s / 2) [S _a T of the _packet / ΔS], which , for example, when ΔS = 4 kHz / ms and the interval T of the _pack = 100 ms is ≈2248 m.

Obviously, without compensating for the dynamic component of the error, this method cannot be used for HFC, and with more intensive maneuvering, only dynamic errors can be more than ten kilometers and, under such conditions, the prototype method is practically inoperative. The claimed method also maintains performance in conditions of intensive maneuvering, providing a reduction in the level of the influence of dynamics on the estimation errors and compensation of the dynamic errors that occur. For example, under the above conditions (1g, ΔS = 4 kHz / ms _burst T = 100 ms), the dynamic component of the error ≈1125 m, and it is estimated and compensated precision (MSE) ≈109 m. Such a loss of precision in conditions ranging maneuvering comparable with errors due to discrete frequency measurement errors. For example, with a Doppler filter width of 15 Hz, under given RMS conditions, instrumental errors in determining the distance are ≈162 m.

In general, the proposed method, under conditions of intensive maneuvering, provides a stable determination of the range from the chirp signals with an accuracy that allows the use of the obtained range estimates to eliminate the ambiguity of HCV measurements and the transition to an accurate estimate of the range in the LCP modes and at low porosity.

The effectiveness of the application of the proposed method in conditions of intensive maneuvering EC also checked by simulation mathematical modeling, the results of which confirmed the achieved technical effect of the invention, consisting in the possibility of simultaneous measurement of distance, radial velocity and acceleration of low-speed maneuvering target with accuracy:

measurements of radial acceleration, exceeding the accuracy of the method-analogue;

measuring the range of signals from the chirp, far exceeding the accuracy of the prototype method, both in the case of uniform motion and in conditions of intensive maneuvering;

measuring the speed of signals from the chirp, far exceeding the accuracy of the method adopted as a counterpart, in conditions of intensive maneuvering.

The claimed method simply can be implemented in the control and information processing systems of the existing radar ID with HFC and LFM. Without changes, the method can be used not only for low-speed maneuvering VC, but also for speed purposes, the Doppler frequencies of which, even when they are shifted by the chirp, are unambiguously measured and are outside the MO zone.

Information sources used

(except for patents and applications indicated in the text of the description of the invention)

1. Handbook of radar. Volume 3. / Ed. M. Skolnik, New York, 1970. Trans. from English (in 4 volumes) // Under the general ed. K.N. Trofimova. M .: Owls. Radio, 1979.

2. Reddy N.S., Swejm M.N. Elimination of ambiguity in range and Doppler frequency shift in radars in radars with a medium repetition rate in the presence of multiple targets, L-46681 translation, All-Union Translation Center, Moscow, 1985.

3. Potter N.S. Ambiguity elimination in high-frequency radar radar, VRE, OT Series, Vol. 11, 1977.

4. Kondratenkov G.S. Radio vision. Earth remote sensing radar systems. - M .: Radio Engineering, 2005. - 368 p.

5. Ryazantsev, L.B., Likhachev, V.P., Shatovkin, P.P. Phase-difference method for determining the acceleration of a fighter approaching with an air target // Proceedings of the MAI, Issue No. 84.

6. Likhachev, V.P., Ryazantsev, L.B. Probabilistic characteristics of the air target maneuver indicator based on the phase difference estimate of the acceleration of convergence. // Successes of modern radio electronics. 2010, №11, p. 10-14.

7. Radar systems of multifunctional aircraft. T. 1. Radar is an informational basis for the combat operations of multifunctional aircraft. / Ed. Kanashchenkova A.I. and Merkulova V.I. M .: Radio engineering, 2006. 656 p.

8. A. Farina, F. Studer. Digital processing of radar information. Accompanying goals. - M .: Radio and communication. 1993, p. 223-224.

9. Kuzmenkov V.Yu., Loginova V.M. Methods and devices for the joint measurement of radial velocity and radial acceleration. Radio engineering and electronics, 1997, Vol. 42, No. 12, p. 1465 ... 1475.

10. Signal processing in multi-channel radar / Under. ed. A.P. Lukoshina. M .: Radio and communication, 1983, p. 307.

11. Taylor J. Introduction to the theory of errors. Per. from English - M .: Mir. 1985. - 272 s., Ill.

Claims (17)

Method for simultaneous measurement of the range, speed and acceleration of a low-speed maneuvering airborne target in pulsed Doppler radar stations at a high pulse repetition rate and linear frequency modulation (chirp), based on radiation at the same repetition frequency F _{n of} three packets of FZI probe pulses (i), (i = 0, 1, 2) with given values of the slope S ₀ , S ₁ , S _{2 of the} intrapulse chirp carrier frequency ƒ ₀ (among which is the slope S ₀ in the first pack is the average of the values of the slope S ₁ and S ₂ in the second and third packs and the increment ΔS ₀₁ , ΔS _{02 of the} values of the slope S ₁ and S ₂ in the second and third packs with respect to the slope S ₀ in the first pack have a different sign), receiving signals reflected from the target of these bursts of pulses, measuring signals from the detected target is ambiguous delays τ _i (intraperiod positions of the target signal), shifted at a given chirp Doppler frequency F _ia (rangefinder frequencies), remembering the values of these time and frequency measurements for all three bursts and characterized in that they emit bursts of pulses at a high repetition rate and based on well-known and stored frequency and time measurements F _ia , τ _i (i = 0, 1, 2), with known values of the repetition frequency F _p , wavelength λ , the constant time interval T of the _pack between the moments of radiation of the nearest bursts of pulses, given the slope S ₀ , S ₁ , S ₂ for all packs with chirp, simultaneously determine (within one measurement session of three packs) the current values of the radial acceleration, speed and distance to goals by you completions of the following computational operations, in which: - calculate the additional slope S _a for chirp, caused by radial acceleration, and the value of the radial acceleration a _C , for which: determine the deviations ΔF _1a , ΔF _{2a of the} measured values of the rangefinder frequency F ₀₁ , F ₀₂ obtained by the second and third packs with chirp, from the base rangefinder frequency F _0a , determined by the first pack with chirp, and the sum of these deviations ΔF _sums according to the formulas

calculate the average value Δτ _sr displacement of the intraperiod position of the target signal for the time T _batch between the nearest moments of radiation of the probe pulse bursts from measurements of the intraperiod position of the target signal τ ₀ and τ ₂ obtained from the first and third bursts

the calculated values of the sum of the deviations of the measured ranging frequencies of the MST from the base frequency and the average offset of the HVAC, with known values of S ₁ , S ₂ given the chirp slope, time interval T of the _pack and wavelength λ determine the value of the slope S _{a of the} additional chirp, due to radial acceleration, and also the value of a and _{c of} this acceleration by the ratios

and _C = (λ / 2) S _a ; - calculate the Doppler shift of the target signal frequency

and the radial velocity V _c corresponding to the moment of radiation of the third pack (using measurements of the rangefinder frequencies F _ia (i = 1, 2) obtained from the second and third packs, calculated values S _a of the additional chirp slope, average offset Δτ _{cf the} intraperiod position of the target signal and known values for a given slope S ₁ and S ₂ chirp for the second and third packs, the time interval T _packs and the wavelength λ), according to the formulas

- determine the distance R ₂ to the target at the time of radiation of the third pack (using measurements of the ranging frequencies F _ia (i = 1, 2) obtained from the second and third packs, the calculated values S _a of the additional chirp slope due to acceleration, average offset Δτ _cf intraperiod position of the target signal and known values for a given slope S ₁ and S ₂ chirp for the second and third pack, the time interval T _pack and the wavelength λ) by the formula

and then, using the calculated range value R ₂ , at a known frequency (period) of pulse repetition F _n = 1 / T _n and measured by signals from the third packet of the intraperiod position of the target signal τ _32, calculate the corresponding pulse repetition period number r and determine the updated range value R at the time of radiation of the third pack by the known formulas:

Where

- the procedure for taking the integer part of the number enclosed in brackets.