RU2314553C1 - System for estimation of onboard radar accuracy characteristics - Google Patents

Abstract

FIELD: equipment for conducting flight tests of flying vehicles and their onboard equipment.

SUBSTANCE: proposed system for testing the onboard radars of flying vehicles has two complexes of onboard trajectory measuring sets mounted on either side of two flying vehicles: fighter and target which include unit bringing the data to common time, radio modems of data transmission lines, onboard part of satellite navigational system, fighter equipment, inertial navigational system, information integration unit, onboard digital computer system, control unit, flight documentation system, display, image shaper and onboard radar carried on fighter. Proposed system also includes ground monitoring and correction station connected with radio receivers of differential corrections on fighter and on target.

EFFECT: enhanced accuracy characteristics of onboard radar.

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Description

The field of technology.

The invention relates to the field of aviation technology, in particular to equipment for conducting flight tests (LI) of aircraft and their on-board equipment (BO), and is intended to study the characteristics of airborne radar stations.

The level of technology.

A known method of experimental determination of the accuracy characteristics of high-precision tracking systems for aviation and space objects and a device for its implementation, see patent for the invention of the Russian Federation No. 2093853, G01S 7/40, 1997.10.20, which determines the components of the distance vector, azimuth angles and location, velocity and acceleration vectors. The device contains gyro-inertial systems, computers, adders, angular velocity sensors, communication channels, the use of which they allow you to automatically receive the specified characteristics in real time. An aiming device is introduced into the device containing the studied tracking system located on the aircraft, the gyro-inertial system is also located on the observed object, the single-time system is installed on the ground; the unit for determining the accuracy characteristics, located on the ground, contains onboard and ground communication channels. When performing an experiment to determine the accuracy characteristics, gyroinertial systems installed on a measuring platform and on an observable aircraft or space object, which, however, cannot accurately determine their angular velocities and are used as measuring instruments to determine the reference values of the relative velocity and acceleration vectors, acceleration, and most importantly, the coordinates needed when testing the radar.

There is a well-known distributed information and control complex for a group of multifunctional aircraft, see RF patent for invention No. 2232102, 7 ВСС 13/00, 07/10/2004, which includes integrated information and control complexes of multifunctional aircraft integrated via inter-board information exchange channels into a single information network apparatuses (MLA), each of which contains radio navigation aids, sighting and sighting systems, recognition systems for images of natural and artificial fields, inertia flax sensors and systems, air sensors and systems, indicator-device control unit intersection coordinate determination, a communication unit and a computer system. The latter in the complex of each MDA group solves the problems of inputting and outputting information and managing information exchange, calculating the main informational parameters of the state and movement of MLA, integrated information processing (COI), as well as additionally storing and updating knowledge about the environment (geophysical fields, landmarks and etc.) and interacting with a group of objects. The composition of the computing system includes computational and logical blocks for the formation of parameters of the state of the MDA (coordinates, speed, angular orientation relative to the inertial space, calculation of the parameters of the mutual movement of the MLA group). All information about the state of the group is transmitted through the channels of the on-board information exchange to all MLA groups, which ensures information unity of the complex of the MLA group.

However, the accuracy of this complex is insufficient for flight tests to determine the characteristics of radar.

A known method of group navigation of moving objects, see the patent for the invention of the Russian Federation No. 2130622, G01S 5/12, 1999.05.20., Which can be used in the differential subsystems of satellite radio navigation systems. The location is achieved by introducing two auxiliary navigation objects in the group navigation method of moving objects and taking into account when calculating the coordinates of the main navigation object, along with the corrective information from the control and correction station, additional corrective information from the auxiliary navigation objects. In this method of group navigation of moving objects, the dependencies of the accuracy of the radio navigation field on the relative position of the control and correction station and the main navigation object are taken into account. The error field of the differential subsystem is approximated taking into account the navigation information received from the spatially separated control and correction station and two auxiliary navigation objects.

However, this method does not allow flight tests to determine the characteristics of radar systems due to the loss of signals from satellite radio navigation systems during the evolution of the measuring (main) and observed aircraft.

Known information system for inter-aircraft navigation, taken as a prototype, RF patent for the invention No. 2222781, G01C 21/00, 2004.01.27, containing a computer installed on each side, inputs connected to the corresponding inertial navigation system (ANN) and the receiver of the satellite navigation system ( SNA), while the output of the first transmitter is connected to the signal generator of the inter-aircraft navigation (MSN), the other input of which is connected via a data line with the transmitter installed on the other side, respectively, the follower but connected to the first adder associated with the radar station (radar-MSN), a unit for estimating the error of signals from the radar-MSN, the second adder, also connected to the radar-MSN, a smoothing filter and a second signal conditioner MSN, while the second input of the first adder is connected to the output of the calculator of the reference values of the signals corresponding to the heading angle and range, the inputs connected in parallel to the first signal processor MSN, and the outputs of both signal conditioners MSN connected to the switch, the control input of which is connected n with a SNA failure sensor, and the output is connected to the output of the information system.

However, the accuracy of performing the radar parameters calibration modes — determining its characteristics — is insufficient for flight tests using this SIT system. In this system, the radar-MSN plays the role of a sensor - a measuring instrument for the coordinates of an aircraft - target. The main reasons for the occurrence of systematic location errors are the restrictions imposed by selective access measures, the delay of signals in the ionosphere and troposphere, the inaccuracy of the ephemeris forecast and the departure of the onboard time scale. A characteristic feature of most residual systematic errors is the increase in their magnitude as the fighter - the main navigation object from the target.

The technical result of the claimed system is to evaluate the accuracy of the radar by determining the characteristics of the radar, estimating the coordinates of the fighter and the aircraft - targets located at a great distance from each other, and comparing them with the characteristics of the radar.

Essential features.

The task is achieved by the fact that in the system for assessing the accuracy characteristics of the airborne radar station, which contains two complexes of airborne trajectory measurements (KBTI) installed on each side of two aircraft (aircraft) - a fighter and targets, including a unit for bringing data to a single time (BPDEV) , a radio data line modem (LPS), the onboard part of the satellite navigation system associated with the BPDV input, consumer equipment, an inertial navigation system associated with the inputs to their outputs the interface of information (USI) connected by the input to the USI of the on-board digital computer system (BTsVS), a control unit connected by its input to the output of the BTsVS, two inputs to the documentation system and to the display via the imager, as well as the onboard radar station connected to the KBTI (BRLS) on an aircraft - fighter to compare the parameters of the aircraft - the target: range, azimuth angle, elevation angle in the polar coordinate system with their accuracy values at fixed points in time received from means of trajectory measurements According to the invention, a control and correction ground station (CCS) was introduced for relative measurements of the SNA coordinates in differential mode in real time with a differential corrections calculator connected at the input to the radio receiver of signals from the SNA, and at the output, with a radio transmitter of differential corrections from the CCS, over the air associated with the radio receivers of differential corrections on the fighter aircraft and targets, the outputs of which are connected to the inputs of the ASE, providing the calculation of the reference coordinates of two aircraft in a Cartesian system with the following transfer to the polar coordinate system to compare them with the parameters of the radar connected to the input of the antenna.

The list of positions in the drawings:

3 - block bringing data to a single time (BPDEV);

4 - on-board digital computer system (BTsVS);

5 - information interface device (USI);

6 - receiver satellite navigation system

7 - documentation system;

8 - control unit with a control panel;

9 - inertial navigation system;

10 - imaging device,

11 - airborne radar station;

12 - display;

13, 16 - radios of differential corrections;

14 - aircraft (LA) - the goal of the day radar;

15 - KBTI on LA targets;

17 - control and correction station (KKS);

18 - a radio receiver;

19 - computer KKS;

20 - transmitter differential corrections from the KKS;

21, 22 - LPD radio modem.

Figure 2 and 3 shows the results of the calculation according to the proposed algorithms, the coordinates of the target, which are combined with the coordinates determined by the radar.

Figure 4 shows the radar errors on the target tracking area, defined as the difference between the simultaneous radar values and the corresponding values recalculated from the SNA measurements.

Information confirming the possibility of carrying out the invention.

The system for assessing the accuracy of radar characteristics (see Fig. 1) contains two sets of a complex of on-board trajectory measurements 2, 15 installed on board two aircraft — a fighter and a target. The KBTI includes a unit for converting data to a single time 3 (BPDEV), a radio modem for the data line 21, an information radio 13, 16 connected to the inputs of the BPDEV, a receiver of the satellite navigation system (SNA) 6, an inertial navigation system 9, an interface device connected to their outputs information 5, and its output - with the on-board computer system 4. The control unit with the control panel 8 is connected to the system, connected by its input to the output of the BCVS, two outputs - to the documentation system 7 and to the display 12 through the shaper 10. The control and correction station 17 is installed in the system, installed on the ground with a differential corrections calculator 19, connected at the input to the signal receiver 18 from the SNA, and at the output, a differential correction transmitter 20 from the KKS, and connected to the differential corrections radio receiver 13 , 16 on the aircraft - fighter and targets, the outputs of which are connected to the input of the ASI 5.

The system operates as follows.

The radar contains a transmitter that creates powerful short-term radio pulses, an antenna system that has a sharp radiation pattern, which “looks through” the space where the target is located, as well as a receiving and indicating device. When radiated electromagnetic waves are fed to the target, they are partially reflected. The reflected waves return to the radar antenna, which is connected to the receiver input during the interval between the pulses of the transmitter using the switch. The latter amplifies and detects the received reflected pulses and feeds them to the indicator input.

Evaluation of accuracy characteristics is based on a comparison of the parameters measured by radar, with their exact values at fixed points in time, obtained from the reference values of the trajectory measurements of the KBTI. When choosing measuring instruments, one proceeds from the requirement that the variance of the error in determining the actual values of the parameters be an order of magnitude smaller than the variance of the measurement errors of the tested system.

In LI BO aircraft, an important place is occupied by the analysis of such radar characteristics as the target detection range, tracking stability, the accuracy of determining the position of the target, which are not determined using the KBTI. The combat effectiveness of military aircraft in the defeat of air and ground targets depends on the characteristics of the radar.

The difficulty in objectively assessing the accuracy characteristics of radar systems in determining the coordinates and speed of an air target lies in the need to simultaneously accurately determine the coordinates of two aircraft (LA), which are at a considerable distance from each other in excess of 100 km. At such a large relative distance, the use of traditional means of external trajectory measurements is not possible.

KBTI is designed to accumulate information on the results of information processing at the pace of the experiment and subsequent post-flight express analysis. This takes into account the whole range of tasks and requirements for the composition and accuracy of the measured parameters. The KBTI equipment contains blocks and devices for receiving, converting, and recording information. Blocks include measuring converters, digital-to-analog and analog-to-digital converters (DAC and ADC), multichannel input / output devices for digital information, computers, control and interface cards, drives and recorders.

KBTI 2 is based on the methods of complex processing of information from precision inertial and satellite information entering the on-board digital computer system (BCVS) 4, which combines on-board computers. The interaction of the BCVS 4 with sensors and consumers is ensured through serial code channels and inter-machine communication channels.

BTsVS 4 solves the problem of receiving information from sensors, processing and analyzing information, generating output data; they also implement service programs to ensure operator modes of operation. To do this, an integrated information processing computer (COI) is used, the result of which is high-precision real values of the parameters of the aircraft motion.

Actual parameter values are used to calculate system errors. If x is the value of one of the parameters of any evaluated characteristics of the aircraft, and x _∂ is the actual value obtained of the corresponding parameter, then the error of this system or characteristic is determined by: Δx = x-x _action. ; x _valid = x-Δx. Improving the accuracy of the formation of the actual values of the flight and navigation parameters is achieved by using the optimal CFI with the implementation of the Kalman filter. The KOI algorithm using redundant information from these ANN, SNA systems provides estimation and compensation in the process of processing errors. Compensation in the ANN signals of 9 parameter errors with the help of the CFI allows the formation of high-precision real values of navigation and flight parameters.

The Kalman filtering algorithm provides the best linear estimates of the state vector of the system X _k at time t _k when X _k is determined from the equation of state:

and the measurement vector Z _k is represented as:

Here ∂ _k , r _k are independent noises with zero mean values and a covariance matrix

Φ _{k + 1, k} is the fundamental matrix, and H _k is the measurement matrix.

The algorithm consists of two stages and has the following form:

- оценка вектора состояния между измерениями.

- assessment of the state vector between measurements.

- assessment when measuring; where X _{k, k + 1} , X _{k, k} are the a priori and a posteriori estimates of the state vector X at the _kth step, P _{k, k-1} , P _{k, k} are the a priori and a posteriori covariance matrices at the _kth step, K _k is the weight matrix.

To overcome the numerical difficulties associated with the possible loss of the symmetry properties and positive definiteness of the covariance matrix, and to increase the accuracy characteristics, we use the filtering method with a quadratic representation of the covariance matrix — the square root method from the matrix based on the representation of the covariance matrix P in the form P = SS, where S upper or lower triangular square matrix.

In the calculator, which is part of the BCVS 4, the actual values of the trajectory parameters are determined according to the information of the SNA 6 and ANS 9. The latitude φ _{∂ of} longitude λ _∂ and height h _{∂ are} determined using the following relations:

where φ _sss , λ _sss , h _sss are the coordinates of the aircraft issued by SNA 6 at time t _sss ; V _N , V _E , V _H are the components of the velocity vector (northern, eastern, vertical) taken from the output parameters of the ANN 9 r _N , r _E are the radii of curvature of the earth ellipsoid, t is the current time. The values of the remaining input parameters are equal to the corresponding values of the parameters of the SNA 6. The actual values of the CBTI 15 (φ _2∂ , λ _2∂ , h _2∂ ), which is installed on LL 14, are also determined.

ее изменения.Due to the fact that the satellite communicates the constant parameters of its orbit through the communication channel, its coordinates φ, λ, h and speeds V _X , V _Y , V _Z are calculated on the aircraft and the range D _n (t) between the aircraft is determined by the received signal at KBTI 2 and companion and

her changes.

изменения дальности определяется либо по скорости "слежения" генерируемого на борту псевдошумового сигнала за принимаемым сигналом, либо по доплеровскому сдвигу принимаемого радиосигнала.Speed

the range change is determined either by the rate of "tracking" of the pseudo-noise signal generated on board the received signal, or by the Doppler shift of the received radio signal.

земной скорости ЛА.Elements of the satellite’s orbit, which can be considered constant for 1-2 hours with high accuracy, are transmitted from the satellite with an interval to all consumers, Cartesian coordinates X _sn , Y _sn , Z _sn are calculated from the elements of the orbit and on-board time for any given (current) point in time. And according to the distances to 4 satellites located at known points in space, the location of the aircraft is determined. From the values of the rate of change of range to 3 satellites, a vector is calculated

ground speed aircraft.

To improve the accuracy of the characteristics, a differential method is used to determine the location coordinates of the aircraft, the essence of which is to identify and take into account, as corrections, highly corrected components of the error of navigation parameters using ground control and correction stations (KKS) 17. At KKS 17, the coordinates and compared with geodetic reference data. Then, the corresponding SNA 6 consumers of the specified area are calculated, which allows them, by introducing amendments, to increase the accuracy of the navigation definition. In this case, the difference measurement method is actually implemented (with respect to the QCS), in which the main part of the constant and slowly changing measurement errors, which are methodological and systemic in nature and are the same for measurements on the aircraft and the QCS, is eliminated. The differential mode is able to eliminate the most significant systematic errors in navigation measurements and, as a result, increase the accuracy of determining the coordinates of the aircraft to 3 ÷ 5 m, the components of the velocity vector to 0.1 m / s.

The navigation aspect of the system is based on the reception of SNA radio signals at KKS 17 and the main object of navigation of LA and LA - target 14, processing the received signals at KKS, the main object of LA and LA - target, calculating at KKS 17 corrections to the measured pseudorange for each of the observed artificial navigation Earth satellites (NLSS) 1, transmitting and receiving the calculated corrections through the communication channel from KKS 17 to the main navigation object of the aircraft and aircraft - targets 14, adjustments of the pseudo-ranges measured at the main navigation object of the aircraft and aircraft - targets 14 by the amount received GOVERNMENTAL from CCF 17 amendments and calculating the coordinates of the main object of the aircraft navigation. In this case, measurements of the accuracy of the radio navigation field at various points in the working area of the differential subsystem SNA - 6-1 are taken into account.

The task of determining the relative location of two aircraft is solved using two sets of KBTI 2 and 15 installed on the aircraft (fighter) and the aircraft - the target, using relative measurements of the SNA in the differential measurement mode. The measurement scheme when performing such LI is shown in figure 1.

Implementation in KBTI 2 of the differential mode of measurements of SNA (in real time or after flight processing) allows trajectory measurements throughout the flight, regardless of the place of testing. The advantage of KBTI 2 is the registration of all necessary information on-board equipment systems with the exact binding of the recorded parameters to a single time scale and the determination of the trajectory parameters of the aircraft (synchronization and recording of information).

The radar 11 gives the coordinates of the target in the polar coordinate system, so the geographical coordinates (latitude, longitude and altitude) determined by the differential SNA measurement mode (latitude, longitude and altitude) of two aircraft must be converted to polar coordinates (range, azimuth, elevation). The coordinates are recalculated in the BCVS 4 according to the following algorithm:

1. The radii of curvature of the first aircraft verticals (fighter and target) are determined

i=1, 2...

i = 1, 2 ...

where N _i is the radius of curvature of the first verticals, and a, e ² is the semi-major axis and the eccentricity square of the ellipsoid, relative to which the coordinates of the fighter φ ₁ , λ ₁ , h ₁ and the target φ ₂ , λ ₂ , h _{2 are} determined.

2. The spatial coordinates of the aircraft are calculated in the Cartesian system of the fighter equipped with radar

where N ₂ is the radius of the verticals of the aircraft of the fighter, N ₂ is the height of the fighter, λ _2,1 is the longitude of the fighter and the target.

3. The coordinates of the target are found in the Cartesian coordinate system associated with the fighter

where X ₁₂ , Z ₁₂ are the coordinates of the target.

4. Find the coordinates of the target in the polar coordinate system associated with the fighter

where D, A _Z , U _M - range, azimuth angles and target location.

5. Radar errors are found by the formulas

For example, obtained as a result of the calculation according to the above algorithms, the coordinates of the target are aligned with the coordinates determined by the radar 11, figure 2, 3.

Errors of radar 11 in the target tracking area, defined as the difference Δ between the simultaneous values of radar 11 and the corresponding values recalculated from the measurements of the SNA, are shown in figure 4.

In the case considered, the error in determining the target range does not exceed 0.12 km and decreases as the aircraft approaches. The errors in determining the angular parameters do not exceed the level of 0.5 degrees, the error in determining the speed is 2 m / s.

ANN 9 platform and strapdown type provides autonomous calculation of the coordinates of the location of the aircraft and flight altitude by integrating accelerations measured by accelerometers. Setting the inertial system for the Schuler period (84.4 min) provides the construction of a vertical unperturbed acceleration in flight. The platform-free ANN 9, in comparison with the platform ones, provides the determination of a larger number of parameters: geographical coordinates, ground speed and components of ground speed, angular positions of aircraft, angular speeds and accelerations, vertical speed and altitude. ANN 9 are built on the basis of laser gyroscopes, providing them with higher reliability and low availability.

The information interface device (USI) 5 is designed to convert sequential codes to BTsVS codes and reverse convert the BTsVS 4 code to serial codes and one-time commands. ASI is connected with the tested on-board equipment for the electrical coordination of the controlled signals and digitalization of the signals of the sensors of the on-board systems. ASI 5 includes an exchange module for interfacing with an information transmission line, executes commands addressed to it, controls the operation of all unit modules, the serial code module receives and issues a serial code. The module of analog and one-time signals receives and issues analog and one-time signals.

Information is input from SNA 6, ANN 9, BRLS 11 using the adapter located at the input of the ASI 5. The subsequent interface module provides full input of information flows in accordance with GOST-18977 (ARIN 427). The set timer makes it possible to temporarily bind each input word, which allows you to determine the cyclogram of the information output of the entire complex.

Information on-board systems SNS 6, ANN 9, radar 11 through an adapter is entered into the input buffer of the BCVS 4 computer. The processed parameters are selected from the input buffer and their primary processing is carried out in accordance with the selected parameters. Then the corresponding procedure is connected in the processing program.

The actual values of the parameters measured in the complex and similar parameters received from the radar 11 are linked to the common time from the block - the source of the single time BPDEV 3, made on the basis of the SNA 6. In the block for matching and synchronizing the timing of the parameters in the input stream linear extrapolation:

where j- = 1, ... n, n is the number of parameters in the input stream, b _i (t) is the current value of the j-th parameter, b _p (t) is the previous value of the j-th parameter, t is the current time, corresponding to j - parameter, t _p - time value at the previous moment, t '- time value at which the combination of information should occur.

The information entered through USI 5 has a time reference at the level of each input word - a time parameter based on an interface timer. The timer captures the moments of receiving information; the initial value of the time parameter is zero. In addition, you need information (parameter) about the system time of the computing system at the time of processing the SNA 6 information, the astronomical time parameter for the output of the SNA 6 information packet, and the time delay parameter for the output of the packet relative time for determining coordinates. The accuracy of the time reference is determined by the resolving ability of the timer located in the USB information input adapter 5.

During testing, the complex implements an interactive mode of operation of the operator and display modes. To do this, the information on the display 12 comes from the control unit 8. The graphic alphanumeric (coordinate) display 12 allows you to observe on the screen the progress of the modes, to control the values of individual parameters of the aircraft systems.

The imager 10 is intended for interaction on a multiplex image transmission line and the formation of image signals. It consists of an exchange module, a graphic controller for a display memory module. The signals are transmitted via the multiplex information transfer bus to the exchange module, which provides their reception and conversion into an information array evaluating the image received by the graphics controller. The graphic controller, by the commands of the exchange module, generates digital signals, backlight signals and control signals.

Documentation system 7 allows you to perform the following operations:

- layout of documents in the form of text tables;

- online loading of document formats in real time;

- operational change of source data for the formation of documents;

- plotting on a printer or plotter of various graphs;

- output of parameter values in a table form to a display, printer, etc.

Control unit 8

- carries out the interaction of subsystems;

- distributes information flows through input adapter channels;

- selects the boot configuration option for various tasks of recording and analyzing information;

- downloads information on the display screen.

Using the control panel in block 8 operational modes of preparation and verification of the complex and the sequence of operation modes are provided.

The complex assumes the presence of an operator on board the aircraft, which analyzes the information during the tests, monitors the performance of flight modes and operation of the investigated radar 11, sets test control actions, and controls the operation of the complex as a whole.

Claims (1)

A system for evaluating the accuracy characteristics of an airborne radar station, containing two sets of equipment for a complex of airborne trajectory measurements (KBTI) installed on each side of two aircraft (aircraft) - a fighter and targets, including a unit for converting data to a single time (BPDEV), a radio modem for the data line (LPD), a receiver of a satellite navigation system (PSNS) associated with the input BPDEV, inertial navigation system (INS), a device for interfacing information (USI) associated with the inputs with the outputs BPDEV, LPD, PSNS, ANN, an on-board digital computer (BTsVS) connected to the input to the IDS, designed for the integrated processing and analysis of information received from on-board means, to obtain the actual values of the parameters of the movement of aircraft and the formation of output data for the information consumer, a control unit connected to an input to the output of the BCVS, two outputs - to the documentation system and to the display through the imager and designed to distribute the streams of received information and for loading information on the display screen, as well as containing the on-board radar station on the fighter aircraft to compare the parameters of the aircraft — the target — range, azimuth angle, elevation angle in the polar coordinate system, measured by the radar, with their accuracy values at fixed times, obtained in the form of reference values from on-board means of trajectory measurements of KBTI, characterized in that a control-correcting ground station (KKS) is introduced for relative measurements by satellite navigation systems in real-time differential mode (SNA) of aircraft coordinates made in the form of a calculator of differential corrections connected at the input to the radio receiver of signals from the SNA, and at the output, with a radio transmitter of differential corrections from the KKS, over the air connected to the radio receiver of differential corrections on the aircraft apparatus - a fighter and with a radio receiver of differential corrections on an aircraft - targets, the outputs of which are connected to the inputs of the corresponding ASE, with the possibility of calculating the reference coordinates of two aircraft in the Cartesian coordinate system with subsequent translation into the polar coordinate system in order to compare them with the radar parameters connected to the input of the ASE of the fighter aircraft, in this case, information is entered into the corresponding BCVS from the indicated airborne assets and radar adapter located at the input of the WSI.

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