Processing of radar information. Study of algorithms for the secondary processing of radar information. A study guide for laboratory work. The principle of measuring the range and direction in the NRS

Adaptive control under a priori uncertainty (nonparametric information processing).

Ticket number 53 Graphics processing software. Software packages for working with raster and vector graphics, their main functions. Full color image processing

Vacuum treatment of liquid steel. The main processes occurring during evacuation. Tasks solved by vacuum processing. Features of the VDP.

Veterinary treatment of farm animals

Question 17 Steel. Classification. Thermal and thermochemical hardening treatment of steels

At the stage of primary and secondary processing, as you know. information is processed from only one radar station (RLS). To control fire weapons with the help of automated control systems, it is necessary to have information about targets within a sufficiently large space, which cannot be provided by one radar. Obtaining information is possible only by creating a single radar field using several radars. Therefore, the problem arises of processing radar information received from several radars.

The processing of radar information from multiple radars is called tertiary information processing (TPI).

To perform their tasks, radar stations are located on the ground in a specific battle formation. Radar visibility zones form a radar field. In this case, the radars can be placed in such a way that their visibility zones will overlap completely or partially (Fig. 4.1). Radar fields with overlapping visibility zones provide better conditions for monitoring the target, but require more radar equipment. In this case, information about the same target can be received simultaneously from several stations. Ideally, these target marks should overlap one another.

However, practically no coincidence is observed due to systematic and random errors in measuring the coordinates of targets, different location times, and also due to errors that occur when taking into account the parallax between the radar stations and the point of tertiary processing when bringing the coordinates of targets to a single system. The latter is a prerequisite for tertiary processing, since all radars determine the coordinates of targets in their coordinate systems, which does not allow information to be combined.

Rice. 4.1. View area horizontal section

In the general case, the discrepancy between marks and trajectories can be either due to errors in measuring the coordinates of targets and different location times, or because there are several targets that create these marks and trajectories. Uncovering this uncertainty, i.e. deciding how many targets are actually in the controlled area, is the main issue of tertiary processing.

In general, at this stage of information processing, the following tasks are solved:

Collection of reports coming from information sources (RLS);

Bringing target marks to a single coordinate system;

Bringing marks to a single reference time;

Identification of marks, i.e., making a decision about their belonging to certain goals;

Averaging the coordinates of several marks of the same target in order to obtain more accurate its coordinates.

Often, especially in a difficult air situation, the task of enlarging information additionally arises during tertiary processing. Tertiary processing devices are relatively easy to implement with specialized electronic computers (computers).

Let us consider in more detail the content of these tasks.

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Introduction
2. DSP systems
3. Optical fiber

4. Gigabit Ethernet(1000base-T)28
5.VPX standard
Conclusion
Bibliography
Introduction
Radar is a field of radio electronics that deals with the use of radio waves to detect, determine coordinates and measure the motion parameters of various objects. All objects of observation in radar are called targets. These include, for example, ships, aircraft, tanks, etc. Operations performed in radar to detect targets, measure their coordinates and movement parameters, are called radar surveillance.
The structure of the radar channel. It includes the radar itself, the radar carrier, the radio wave propagation medium, a group of objects, a navigation system, and a channel indication and control system (Fig.%). All these elements of the structure are involved in the process of detecting and determining the characteristics of given objects.
A group of objects consists of given objects (targets), auxiliary objects (landmarks), accompanying objects (background), objects emitting or re-emitting interference signals (interference sources).
Targets are given objects that can have a different physical nature: air targets (airplanes, missiles, clouds, rain, atmospheric turbulence, etc.), ground targets (troop concentrations and certain types of equipment, airfield runways and agricultural land, engineering structures and roads, etc.), maritime targets (ships, ice fields, sea surface).
Landmarks are auxiliary objects that help solve the main task of detecting and determining the characteristics of targets. So, for example, a landmark - an object with known coordinates - is used to accurately determine the coordinates of targets located near this object. Background - Accompanying objects that usually interfere with target detection. So, if a small target is observed against the background of the underlying (terrestrial) surface, then the background masks the target. The background signal is much larger than the target signal, which requires a special signal processing system to suppress the background signal and extract the target signal.

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Figure 1. The structure of the radar channel.
radar channel optical fiber
Active and passive jammers are objects that radiate or re-radiate signals that interfere with the detection of target signals. Interference is usually used in the process of electronic warfare, but it can also be unintentional (natural), for example, in the form of radiation from other radio transmitting devices. Passive interference is created by special reflectors (clouds of dipoles, aerosols and other formations), reflections from which mask target signals.
The medium of propagation of radio waves is the space between the radar and the object. It is usually assumed that the electromagnetic wave from the object to the radar propagates in a straight line and at a constant speed. The presence of inhomogeneity of the medium (refractive index) introduces errors into the process of measuring the characteristics of the target, and energy losses due to absorption in the medium lead to a decrease in the target detection range. Therefore, when solving radar problems, it is necessary to take into account the characteristics of the propagation medium.
Radar - includes the actual radar equipment ("hardware") and software (software) for the operation of the radar. The radar equipment includes the following main blocks:
antenna and transceiver modules. The antenna-feeder devices of the modules provide directional radiation and reception of radio waves, taking into account their polarization. Transmitting modules provide amplification, amplitude and phase modulation of radio frequency oscillations. Receiving modules provide low-noise amplification and frequency conversion of received radio frequency oscillations;
a signal synthesizer that generates oscillations of a given radio frequency, modulation and conversion frequencies for transceiver modules;
a signal processing processor that performs a given algorithm for processing received oscillations (synthesizing aperture) using analog and digital devices;
Onboard computer for control and data processing, which ensures the coordination of the operation and modes of all radar devices and the radar carrier in accordance with the task being solved, as well as processing data from the output of the signal processor.
In addition to the listed components of the radar, it also includes technical diagnostic devices, power supplies, a signal distribution network and switching devices.
The navigation system supplies the necessary information to the control signal processing systems.
The indication and control system provides communication between the operator and the radar using information display devices of intelligent control systems implemented using a computer.
The radar carrier performs not only transport functions, but also provides a given spatial position of the radar (trajectory), based on the task of generating the required space-time trajectory signal.
In accordance with the given mode of operation, the signal synthesizer generates high-frequency oscillations of the carrier frequency of the probing signal, as well as the conversion and modulation frequencies of the signals.
The emitted electromagnetic wave, having passed the propagation medium from the radar station to the object, forms the irradiation field of the object. Depending on the properties of the object and the parameters of the irradiation field, characterized by the reflection function of the object, an EMW scattered by the object is formed, propagating towards the radar. The EMW reflected from the object, having passed the propagation medium from the object to the radar, excites the field at the aperture of the receiving antenna modules.
The signal processor and the onboard computer execute the specified algorithms for synthesizing the aperture, detection, determining the coordinates and recognizing the target, ensuring noise immunity and other algorithms. The received data is used by the operator and fed into other systems (intelligence, weapons, defense, etc.).
1. Methods for obtaining radar information
The carriers of information about the targets are the signals received by the radar. Reception of these signals is provided as a result of secondary radiation, re-emission or own radiation of radio waves by the target. A distinction is made between active radar with a passive response, active radar with an active response and passive radar, respectively.
Active radar with a passive response is based on the use of the effect of secondary radiation (reflection) of radio waves (Fig. 1, a). Its active character consists in irradiating the target with powerful probing vibrations. The passive response to radiation is the secondary emission of radio waves. Features of the secondary radiation significantly affect the nature of this method of radar. Active radar with a passive response is also significantly affected by the nature of the placement of the receiving and transmitting equipment in position. If the receiving position is combined with the transmitting one, the active radar means is called combined.
The combined means often contains one antenna switched alternately for transmission and reception. It is possible to separate the receiving and transmitting positions by a distance d, called the base. Bases are not only constant d = const (Fig. 1, b), but also variable (Fig. 1, c). The receiving point, for example, the homing head (Fig. 1, c), is located on the rocket, so that d = var. Along with single-base (two-position) spaced active radar means, multi-base (multi-position) ones are possible. In connection with the complication of radar tasks, interest in spaced radar means has recently increased significantly.
Rice. 1. Generalized block diagrams explaining the essence of radar methods.
Active radar with an active response (secondary radar) allows you to obtain reliable information about your objects (for example, ships, aircraft, tanks, etc.). To do this, they are irradiated (Fig. 1, d) with interrogating (probing) signals. Responders are installed on the objects, i.e., transceivers that re-emit received (emit response) signals. Carrier frequencies, modulation laws (codes) of interrogation and response signals can vary over a wide range. This provides identification of the nationality of objects (“friend or foe”) and individual identification. Active response is also widely used in ATC tasks.
Passive radar uses the intrinsic radiation of the elements of the target and their immediate vicinity. Radiations are generated by heated areas of the surface, communication, location and navigation aids (including flight safety), electronic warfare equipment, ionized formations of various types. In the general case, a passive radar facility can be placed at one (Fig. 1, e) or several spaced positions. On the principles of passive radar work, in particular, means of electronic intelligence of radiation. Passive and active radar means can form a single whole - these will be active-passive radars.
The character of space probing is of great importance for active and active-passive SRL. Increasing the ratio of the antenna size to the wavelength, as is known, achieve a high directivity of the antennas.
The high directivity of the probing radiation ensures the concentration of its energy, facilitating the subsequent selection of reflected signals. Probing of different sections of space is therefore often carried out non-simultaneously, i.e., along with a simultaneous survey of sections of space, a sequential survey is realized. Since the oscillations radiated in each direction are usually modulated in time, the modulation laws for different directions do not match.
In this case, spatio-temporal modulation of probing oscillations takes place. It is achieved by temporal modulation in the transmitters and by moving the directional characteristics of the transmitting antennas in space. Possible types of spatio-temporal modulation provide a consistent survey of space according to a rigid program or according to a flexible program, depending on the results of current observations. To increase the efficiency of the review, antennas with electrically controlled beam position of the HEADLIGHT type are used. The parameters of the received radar signals and their use for measuring the coordinates of targets are affected by the properties of the medium in which radio waves propagate. The simplest and most basic is the case of propagation in free space, which is assumed to be: 1) homogeneous; 2) isotropic; 3) non-dispersive. This means that the propagation speed of radio waves: 1) is the same for all elements of this space; 2) does not depend on the direction of propagation and polarization of the wave; 3) does not depend on the oscillation frequency (s? 3 10 8 m/s). Probing and reflected signals propagate along rectilinear trajectories without distortion of their shape. The delay times td of the signals reflected from point targets relative to the probing ones are determined for spaced (Fig. 1, b) and combined (Fig. 1, a) radars by the relations
tc = (D1 + D2)/s and tc = 2D/s.
The range to the target is thus encoded in the time structure of the received oscillations. For combined radars, the range is uniquely determined by the delay time:
Dts \u003d with tz / 2.
When using spaced reception points or one multi-element antenna, we can talk about the spatio-temporal structure of the received oscillations. The set of time delays characterizes not only the ranges, but also the angular positions of the targets. With a small spacing of the receiving elements (within the phased array), when the difference between the delays of the envelope signals to the receiving elements can be neglected, the angular coordinate of the target is found from the distribution of the initial phases of the received oscillations. The formation of DND is associated with the same distribution. By rotating the ADS (scanning), one can relatively easily measure the angular coordinates - azimuths and elevation angles of targets, for example, by the maximum of the reflected signal (Fig. 2, a), ensure their angular resolution (Fig. 2, b). Information about different angular directions with single-channel reception arrives sequentially in time, with multi-channel reception (when the characteristics of Fig. 2, b refer to different reception channels) it can be received in parallel, almost simultaneously.
Rice. 2. Scheme illustrating the principle of measuring angular coordinates and resolving targets
Rice. 3. Structural diagram of the simplest pulse radar
We will explain the implementation of the principles of target detection, measurement of their angular coordinates and range using the example of a block diagram of the simplest active pulse radar with a combined transceiver antenna and one receiving channel (Fig. 3). An important element of the radar is the synchronizer that triggers its main elements. Probing with short radio pulses ensures non-simultaneity of reception and emission. This allows the use of a common antenna switched by an antenna switch for transmitting and receiving.
After radiation from the ES, the antenna is connected to the receiver. PPI provides the operator with the possibility of detecting the secondary radiation of the target, measuring the distance to the target and its angular coordinates (azimuth). The use of automation circuits is envisaged. The latter connect the indicator device with the antenna, provide information about the current position of the DS, and hence the angular coordinates of the targets, as well as control this diagram (the control loop is not shown in Fig. 3).
In a more general case, the reception can be multi-channel, the duration of the signal does not have to be small. The receiving and transmitting antennas can be separated (even in a co-located location).
An important role in radar is played by the target movement factor, which causes a change in the time delays of individual elements, and hence the entire signal structure. So, the radial movement of the target relative to the combined pulse radar: 1) changes the delay of successively received pulses; 2) leads to a change in the carrier frequency known from physics - the Doppler effect. Both effects separately can be used to measure the radial velocities of the target and their velocity resolution. As explained below, they are manifestations of the effect of signal transformation due to target movement. Speed selection is widely used to protect against passive interference.
With any of the radar methods, the incoming signals are often weak. This is especially true for active radar, where there is a double scattering of energy: on the way to the target and back. To isolate weak signals, a number of measures are taken: if possible, increase the dimensions of the transmitting and receiving antennas, the average power of the probing oscillations; use highly sensitive (low noise) input elements of radio receivers.
2. DSP systems

Stage 1. Digital filtering and spectral analysis

At this stage of development (1965–1975), the main subject area of DSP theory was digital filtering and spectral analysis (Fig. 2), and both directions were considered from a common position of frequency representations. The common basis for developing areas was the synthesis of digital filters of frequency selection. The basic provisions of the theory of DSP were laid down and tested in fact on the theory of discrete systems and the theory of circuits using a set of computer algorithms known by that time and, above all, the Fast Fourier Transform (FFT) algorithm.

Fig 2 - main subject area of DSP theory

The main problems that have been effectively solved in these years include: machine approximation of the transfer function of digital filters (DF) in the class of filters with finite (FIR filters) and infinite (IIR filters) impulse response, development of high-speed convolution algorithms and low-noise structures IIR filters, building digital spectrum analyzers based on the use of bandpass filters and the FFT algorithm.

The possibilities of technical implementation of digital filters and spectrum analyzers during this period can be characterized as a stage of machine simulation in real time using small computers or specialized devices built on ICs of a medium degree of integration. The first digital devices from the point of view of today's ideas had low efficiency and had extremely limited use, usually associated with military technology. However, the predicted successes in the field of microelectronics and digital circuitry inspired hope for a speedy radical change in this state of affairs.

Stage 2. Multirate filtering and adaptive signal processing

In the early 1970s, the first single-chip microprocessors (MP) appeared - the "heralds" of a new wave of the computer revolution. A new stage in the formation of DSP technology and computer technology begins.

New opportunities open up and new challenges arise. The DSP theory is entering the next stage of its development, which can be conditionally limited to the period from 1975 to 1985. It is during this period that the four main interrelated directions of the modern DSP theory are formed (Fig. 3).

The first direction - digital frequency selection of signals, consolidates and systematizes achievements in the field of designing digital bandpass filters and their sets. The most original works in this direction were associated with the development of the theory of multirate signal processing based on the effects of decimation in time and frequency.

The second direction is fast signal processing algorithms, focused on building high-speed DSP algorithms by eliminating the "redundancy" of transformation operations and replacing labor-intensive multiplication operations with addition and shift operations (numerous modifications of the FFT algorithm and methods of number-theoretic transformations).

The third direction is adaptive and optimal signal processing, covering a wide range of methods for solving problems of optimal filtering (Wiener, Kalman filters, etc.) and signal processing under conditions of a priori uncertainty about the nature of the dynamic process under study.

The fourth direction is the processing of multidimensional signals and fields, which is a natural development of the processing of one-dimensional signals in the case of multidimensional digital systems.

These directions are interrelated with each other, and this relationship is based both on a common mathematical basis, “feeding” all four directions, and on the direct use of the main provisions and methods of one direction in others.

Stage H. Optimal design on signal processors

In the first half of the 80s, first NEC (Japan), then Texas Instruments (USA) announced the industrial production of the first mPD7720 and TMS32010 signal processors and thus marked the opening of a new era in DSP technology - the era of VLSI signal processing. The new class of microprocessor systems was actually a family of single-chip microcomputers, oriented by their internal architecture to a highly efficient hardware and software implementation of classical DSP algorithms. In a relatively short period of time - 15 years, digital signal processors (DSPs) have gone through several stages of development. Companies such as Motorola, AnalogDevices, AT&T, SGS Thomson (USA) and others entered the competitive struggle in the market of advanced electronic technologies. microprocessor DSP systems. Reducing the cost and expanding the functionality of VLSI signal processing contributed to the widespread practical use of DSP methods in various fields of scientific and industrial human activity.

A new stage in the development of DSP theory (from the mid-80s) is the intensive introduction of digital signal processing methods using single-chip DSPs and multiprocessor systems built on their basis. The theory of DSP, progressively moving in all the above directions, is increasingly developing in the direction of practical use in specific areas, taking into account the limitations imposed by the internal resources of the signal processors used. Traditionally, the basic areas of application of DSP technology remain: digital processing of speech, sound, images, as well as statistical DSP in radio engineering, communications and control. But it was during this period that the methods and techniques of DSP from the sphere, as a rule, of military technologies, move into the sphere of intensive commercial development.

Intense competition in the market of new information and computer technologies has contributed to a breakthrough in the field of methodology and technology for designing DSP systems, providing a significant reduction in development time. The general concept of optimal automated design of DSP systems is formulated. Powerful software tools are being created to support computer-aided design, starting from the stage of system modeling and ending with circuit implementation on signal processors and VLSI signal processing. These include such integrated shells as MATLAB from TheMathWorks, Inc., Hypersignal from Nuregcertion, Inc., digital filter synthesis packages QEDesign from MomentumDataSystems (USA), DIFID and PICLOR from Radis, Ltd. (Russia), etc. The development of multiprocessor DSP systems focused on processing information flows at the rate of their receipt required the creation of specialized control software - real-time operating systems (RTOS) optimized for DSP systems. The SPOX RTOS from SpectromMicrosystems, Inc. has become famous and widely used. (USA) and Virtuoso from EonicSystems, Inc. (Belgium).

Stage 4. Single-chip multiprocessor systems and optimal design on FPGA

The current stage in the development of signal processing methods and techniques in the second half of the 1990s is determined both by the new unique capabilities of single-chip multiprocessor DSPs (TMS320C80 family) and by the use of architecturally reprogrammable VLSI DSPs based on programmable logic integrated circuits (FPGAs). Having up to 1 million logic gates on a chip and operating at an internal clock frequency of up to several hundred megahertz, signal processing FPGAs firmly occupy their niche between specialized custom-made VLSI and universal DSPs, intensively expanding the scope of reprogrammable VLSI DSP and displacing signal processors from the high-tech market .

The systems designed on FPGAs combine the ultra-high performance of custom-made VLSIs and the high flexibility of DSPs at the level of architectural adaptation to a given class of algorithms, as well as the ability to place the entire system structure, including non-standard peripherals, on a single FPGA chip. In those cases when the system being designed should be focused on solving complex, branched real-time processing algorithms at various input data stream rates, the highest efficiency is achieved with the combined use of FPGAs and signal processors.

The new concept of building a DSP system is based on the wide use of the potential capabilities of FPGAs and the optimal design methodology that guarantees the achievability of the specified quality indicators with minimal hardware costs. At the same time, the emphasis is still shifting towards applied systems, the development and industrial implementation of which are accelerating.

At the same time, questions of the general theory of DSP do not lose their significance. Among the most urgent problems of the theory and technology of DSP are:

Systematization of methods and algorithms for digital signal processing in various areas and creation of application software packages for automated design of DSP systems;

Development of methodology and application packages for optimal design of DSP systems based on signal processors and FPGAs;

Development of new concepts in the main areas of DSP theory - multi-rate processing, fast algorithms, adaptive processing, spectral estimation, time-frequency processing, wavelet and fractal transformations, nonlinear filtering, multidimensional signal processing, etc.

3. Optical fiber

Fiber optic lines are designed to move large amounts of data at very high speeds. In a fiber optic cable, digital data is propagated along optical fibers in the form of modulated light pulses. This is a relatively reliable (secure) transmission method, since no electrical signals are transmitted. Therefore, the fiber optic cable cannot be opened and data intercepted, which is not immune to any cable that conducts electrical signals. In addition, wired communication problems such as EMI, crosstalk (crosstalk), and the need for grounding are completely eliminated. In addition, the attenuation per unit length is extremely reduced, allowing fiber optic links to be extended without signal regeneration over much longer distances, up to 120 km.

An optical fiber is an extremely thin glass cylinder, called a core, covered with a layer of glass, called a sheath, with a different refractive index than that of the core. Sometimes optical fiber is made from plastic. Plastic is easier to use, but it transmits light pulses over shorter distances compared to glass fiber. Each glass fiber only transmits signals in one direction, so the cable consists of two fibers with separate connectors. One of them is for transmitting and the other for receiving. The rigidity of the fibers is increased by a plastic coating, and the strength is increased by Kevlar fibers. Fiber optic cable is ideal for creating network backbones, and especially for building-to-building connections, as it is insensitive to moisture and other environmental conditions. It also provides increased secrecy of transmitted data compared to copper, since it does not emit electromagnetic radiation, and it is almost impossible to connect to it without destroying the integrity. The disadvantages of optical fiber are mainly associated with the cost of its installation and operation, which are usually much higher than for a copper transmission medium. This difference has become habitual, however, in recent years it has begun to smooth out. Fiber itself is only slightly more expensive than Category 5 UTP. But regardless of these advantages and disadvantages, the use of fiber brings with it other problems, such as the laying process. Laying fiber optic cable is basically the same as laying copper cable, but attaching connectors requires a fundamentally different tool and technical skills.

There are two different types of fiber optic cable:

multi-mode or multi-mode cable, cheaper, but of lower quality;

single-mode cable, more expensive, but has better performance compared to the first.

The essence of the difference between these two types comes down to different modes of passage of light rays in the cable. In a single-mode cable, almost all beams travel the same path, as a result of which they reach the receiver at the same time, and the waveform is almost not distorted. A single-mode cable has a central fiber diameter of about 1.3 µm and only transmits light at the same wavelength (1.3 µm). Dispersion and signal loss are very small, which allows you to transmit signals over a much greater distance than in the case of using a multimode cable. For single-mode cable, laser transceivers are used, using light only with the required wavelength. Such transceivers are still relatively expensive and not durable. However, in the future, single-mode cable should become the main type due to its excellent performance. In addition, lasers are faster than conventional LEDs. Signal attenuation in a single-mode cable is about 5 dB/km and can even be reduced to 1 dB/km. In a multimode cable, the paths of light rays have a noticeable spread, as a result of which the signal shape at the receiving end of the cable is distorted. The central fiber has a diameter of 62.5 µm and the outer sheath diameter is 125 µm (this is sometimes referred to as 62.5/125). A conventional (non-laser) LED is used for transmission, which reduces the cost and increases the life of the transceivers compared to a single-mode cable. The wavelength of light in a multimode cable is 0.85 μm, while a spread of wavelengths of about 30 - 50 nm is observed. The permissible cable length is 2 - 5 km. Multimode cable is the main type of fiber optic cable nowadays as it is cheaper and more widely available. The attenuation in a multimode cable is greater than in a single mode cable and is 5 - 20 dB/km. The typical delay for the most common cables is about 4-5 ns/m, which is close to the delay in electrical cables.

3.1 Optical fiber standards

If we compare multimode fibers with each other (Fig. 2.1 a, b), then the gradient fiber has better technical characteristics than stepped fiber in terms of dispersion. This is mainly due to the fact that the intermode dispersion in graded multimode fiber - the main source of dispersion - is much smaller than in stepped multimode fiber, resulting in a higher bandwidth for graded fiber. A single-mode fiber has a significantly smaller core diameter compared to a multimode fiber and, as a result, due to the lack of intermode dispersion, a higher bandwidth. However, it requires the use of more expensive laser transmitters.

In FOCL, the following fiber standards are most widely used (Table 2.1):

Table 2.1 Optical fiber standards and their applications

Multimode fiber	single mode fiber
MMF 50/125 gradient fiber	MMF 62.5/125 gradient fiber	SF (NDSF) stepped fiber	DSF dispersion-shifted fiber	NZDSF Non-Zero Dispersion Shifted Fiber
	LAN (Ethernet, Fast/Gigabit Ethernet, FDDI, ATM)	Long networks (Ethernet, Fast/Gigabit Ethernet, FDDI, ATM), SDH backbones)	Ultra-long networks, superhighways (SDH, ATM)	Ultra-long networks, superhighways (SDH, ATM), all-optical networks

multimode gradient fiber 50/125 (Fig. 2.1 a);

Multimode gradient fiber 62.5/125 (Fig. 2.1 b);

Single-mode stepped fiber SF (dispersion-shifted fiber or standard fiber) 8-10/125 (Fig. 2.1 c);

single-mode dispersion-shifted fiber DSF 8-10/125 (Fig. 2.1 d);

NZDSF non-zero dispersion-shifted single-mode fiber (the refractive index profile of this fiber is similar to the previous type of fiber).

Rice. 2.1 a) Stepped multimode fiber

Rice. 2.1 b) Gradient multimode fiber

Rice. 2.1 c) Stepped Single Mode Fiber d) Dispersion Shifted Single Mode Fiber (DSF or NZDSF)

Most fiber optic devices use the infrared spectrum region in the range from 800 to 1600 nm, mainly in three transparency windows: 850, 1310 and 1550 nm, Fig. 2.8. It is the vicinity of these three wavelengths that form the local minima of signal attenuation and provide a greater transmission range.

3.2 Optical fiber connectors

ST. Was developed in 1985 by AT&T, now Lucent Technologies. The design is based on a ceramic tip (ferule) with a diameter of 2.5 mm with a convex end surface. The plug is secured to the socket by a spring-loaded bayonet element (similar to BNC connectors used for coaxial cable). ST connectors are the cheapest and most common type in Russia. It is slightly better than the SC in terms of tough environments thanks to its simple and strong metal construction (allows more room for brute force).

As the main disadvantages, one can name the complexity of marking, the laboriousness of connection, and the impossibility of creating a duplex plug.

SC. It was developed by the Japanese company NTT, using the same ceramic tip as in ST, with a diameter of 2.5 mm. But the main idea is a lightweight plastic body that protects the tip well and provides smooth connection and disconnection in one linear motion.

This design allows a high density of mounting, and easily adapts to convenient dual connectors. Therefore, SC connectors are recommended for creating new systems, and are gradually replacing ST.

Additionally, two more types should be noted, one of which is used in a related industry, and the other is gradually gaining popularity.

FC. Very similar to ST, but with a threaded lock. It is actively used by telephonists of all countries, but practically does not occur in local networks.

LC. New "miniature" connector, structurally identical to SC. So far, it is quite expensive, and its use is meaningless for "cheap" networks. As the main argument "for" the creators cite a high density of editing. This is a serious enough argument, and in the distant (by telecommunications standards) future it is quite possible that it will become the main type.

3.3 Information transmission over optical fiber

If compared with other methods of information transfer, then the order of magnitude of TB / s is simply unattainable. Another advantage of such technologies is the reliability of transmission. Fiber optic transmission does not have the disadvantages of electrical or radio signal transmission. There is no interference that can damage the signal, and there is no need to license the use of the radio frequency. However, not many people understand how information is transmitted over fiber in general, and even more so are not familiar with specific implementations of technologies. We will consider one of them - DWDM technology (dense wavelength-division multiplexing).

First, let's look at how information is generally transmitted over an optical fiber. An optical fiber is a waveguide through which electromagnetic waves propagate with a wavelength of the order of a thousand nanometers (10-9 m). This is a region of infrared radiation not visible to the human eye. And the main idea is that with a certain selection of the fiber material and its diameter, a situation arises when for some wavelengths this medium becomes almost transparent, and even when it hits the boundary between the fiber and the environment, most of the energy is reflected back into the fiber. This ensures the passage of radiation through the fiber without much loss, and the main task is to receive this radiation at the other end of the fiber. Of course, such a brief description hides the huge and difficult work of many people. One should not think that such material is easy to create or that this effect is obvious. On the contrary, it should be treated as a big discovery, as it now provides the best way to convey information. You need to understand that the waveguide material is a unique development and the quality of data transmission and the level of interference depend on its properties; The waveguide insulation is designed to minimize the amount of energy escaping to the outside.

One of the relatively new data transmission technologies is Fiber Channel.

Fiber Channel technology is based on the use of optical fiber as a data transmission medium. The most common application of this technology today is in high-speed storage area networks (SANs). Such devices are used to build high-performance cluster systems. Fiber Channel technology was originally created as an interface that allows high-speed data exchange between hard drives and a computer processor. Later, the standard was supplemented and now defines the interaction mechanisms not only for data storage systems, but also for the interaction of several nodes of a cluster system with each other and with data storage facilities.

Fiber Channel technology has several advantages over other transmission media, the most important of which is speed. Fiber Channel technology provides a data transfer rate of 100 Mbps. The second important advantage is the possibility of signal transmission over very long distances. Data exchange using a light signal instead of an electric one makes it possible to transmit information over distances up to 10-20 km without the use of repeaters (when using a single-wavelength cable). The third advantage of Fiber Channel technology is complete immunity to electromagnetic interference. This quality allows you to actively use the optical transmission medium even in industrial premises with a large amount of electromagnetic interference. The fourth advantage is the complete absence of signal radiation to the environment, which makes it possible to use Fiber Channel in networks with increased requirements for the security of processed and stored data.

The main disadvantage of Fiber Channel technology is its cost: optical cable, with all its associated connectors and installation methods, is significantly more expensive than copper cables.

4. Gigabit Ethernet(1000base-T)

The development of Gigabit Ethernet standards has led to specifications for UTP copper cable, single-mode fiber, and multi-mode fiber. On Gigabit Ethernet networks, bits are transported in a fraction of the time they take on 100 Mbps and 10 Mbps networks. In signals traveling faster, the bits become more susceptible to noise and therefore timing is critical. The performance question is based on how quickly the NIC or interface can change voltage levels and how reliably that voltage change can be detected at a distance of 100 meters on the receiving NIC or interface.

1000 Mbps - Gigabit Ethernet

At these higher speeds, data encoding and decoding is more complex. Gigabit Ethernet uses two separate encoding steps. Data transmission is more efficient when codes are used to represent the bit stream. Data encoding allows synchronization, efficient use of bandwidth and improved signal-to-noise ratio characteristics.

1000BASE-T Ethernet provides full duplex transmission using all four pairs in a Category 5 or later UTP cable. Gigabit Ethernet over copper wire allows an increase in speed from 100 Mbps per pair of wires to 125 Mbps per pair of wires, or 500 Mbps for all four pairs. Each wire pair carries signals in full duplex, doubling 500 Mbps to 1000 Mbps.

1000BASE-T uses 4D-PAM5 line encoding to achieve a data throughput of 1 Gbps. This coding scheme allows signals to be transmitted over four wire pairs simultaneously. It converts an 8-bit data byte into a simultaneous transmission of four code points (4D), which are sent over the media, one on each pair, as Level 5 Pulse Amplitude Modulated (PAM5) signals. This means that each character corresponds to two bits of data. Because information travels along four paths simultaneously, the circuitry must separate the frames at the transmitter and reassemble them at the receiver. The figure shows a representation of the circuit used in 1000BASE-T Ethernet.

1000BASE-T allows data to be transmitted and received in both directions - on the same wire and simultaneously. This traffic flow creates constant collisions on wire pairs. These collisions result in complex stress patterns. Signal-detecting hybrid circuits use sophisticated techniques such as echo cancellation, Level 1 Forward Error Correction (FEC) and smart voltage levels. Using these methods, the system achieves a throughput of 1 gigabit.

To help with synchronization, the Physical Layer encapsulates each frame with start-of-stream and end-of-stream delimiters. Cycle timing is maintained by continuous streams of IDLE (inactive) symbols sent on each wire pair during the interframe interval.

Unlike most digital signals, where there are usually several discrete voltage levels, 1000BASE-T uses many voltage levels. During inactive periods, there are nine levels of voltage on the cable. During data transfer, there are up to 17 voltage levels on the cable. With so many states combined with the effects of noise, the signal on the wire looks more like analog than digital. Similar to analog, the system is more susceptible to noise due to crimp and cable problems.

Benefits of Gigabit Ethernet To support the growing demand for network performance, Gigabit Ethernet includes extensions to fast fiber connections at the Physical Layer. This provides a tenfold increase in MAC (Media Access Control) at the data layer (Data Layer) in order to support video conferencing and other traffic-intensive applications. Gigabit Ethernet is compatible with the most popular network architecture, Ethernet. In 1996, according to IDC research forecasts, more than 80% of computer networks used Ethernet. Ethernet dominance is expected to continue beyond 1998, especially if this interoperable and scalable standard moves to gigabit speeds. In addition to the wide choice of products and manufacturers on the market, this dominance has led to steady declines in the price of Ethernet hardware.

Sustained cost reduction for Ethernet and Fast Ethernet products. Similar trends are expected for Gigabit Ethernet products. (Dell Oro Group) Information technology departments of companies adopting Fast Ethernet, and ultimately Gigabit Ethernet, to increase network performance will see:

Increasing levels of network performance, including traffic localization and high-speed inter-segment data transfer

· Improved network scalability -- this will make it easy to add users and manage the network.

· Reducing, over time, the total cost of hardware.

5.VPX standard

VPX is a new embedded architecture for harsh environments based on today's high speed serial interconnects. The VPX standard is historically a successor to the well-known VME standard, which is widely used in the design of military electronics. To date, the VME standard is obsolete, although it is still used by a number of companies as the basis for new developments. The same can be said about the widespread PICMG 2 standard using the CompactPCI data bus. The main reason why these standards are now irrelevant is the low bandwidth of the parallel data buses used (40 MB/s for VME64). First of all, such low rates do not meet the needs of applications related to 126 ISSN 0236-3933. Bulletin of MSTU im. N.E. Bauman. Ser. "Instrument making". 2012 processing of visual information, as well as data processing in broadband radar stations (RLS). In addition, 6U boards (160233 mm) are characterized by insufficient rigidity, low mechanical resonant frequencies, and do not work satisfactorily in high vibration conditions. High-speed serial transceivers (transceivers) are the main technology that allows today to transfer data at high speed both within the same crate (case with a set of boards) and between several remote devices. Such transceivers are now supplied with an increasing number of semiconductor computing devices: programmable logic integrated circuits (FPGA), digital signal processors (DSP), ADC, DAC, etc. Differential signal transmission method, high transmitter power, the use of various kinds of equalizers that compensate signal distortion, three-dimensional crystal design technologies allow data transmission at speeds up to 28 Gb / s over a single wire pair. Combining several high-speed transceivers allows you to get a transmission rate of 100 Gb / s and higher on a single data bus. Currently, 100 Gb / s technology is already standard and is offered by leading chip manufacturers (Xilinx, Altera, Texas Instruments), as they say, on a turnkey basis. Manufacturers provide information about the features of the design of printed circuit assemblies, give recommendations for debugging, provide methods for verifying such designs, and also provide their fairly complete software support. The resulting gap in data transfer technology between modern chips and special-purpose modules inside crates was taken into account when developing the VPX, VPX REDI and OpenVPX standards. The required data transfer rate in the VPX standard is ensured primarily by the use of connectors specially designed for the transmission of high-speed differential signals, which are used to connect between cells of a device with a backplane (the so-called backplane).

Such connectors are a set of small angled printed circuit boards (so-called wafers) stacked using a plastic holder. On the printed circuit boards, there are drawings of conductors of various configurations depending on the purpose of the connector: signal connectors with differential or unbalanced tracks; power connectors with wide layers of conductive copper. The mating part of the connectors, installed on the backplane, is a set of spring contacts placed in a plastic holder. VPX signal connectors have a guaranteed characteristic impedance (100 or 50 ohms), which is ensured by the appropriate configuration of the conductors and the printed circuit board of the connector. This allows you to meet the conditions of signal integrity when it passes from cell to cell through two pairs of interconnects. Power connectors VPX are made using the technology of manufacturing printed circuit boards from blanks with thick copper films (from 75 microns), which provides a current load of up to 36 A per connector containing three power "wafers". Thus, VPX standard devices support high-energy high-speed digital and digital-to-analog circuits. It should also be noted that with good electrical characteristics, VPX connectors have a high level of vibration resistance and sufficient mechanical strength. This is achieved both through the design of the connectors themselves and through the use of a well-thought-out system of guide pins. During the development of the standard, numerous tests were carried out for resistance to mechanical, thermal, chemical and other influences, which confirmed the high stability of the electrical properties of the connectors.

An equally significant factor in ensuring high-speed connections between modules is the characteristics of the backplane. The VPX standards require modular backplane interconnection using high-speed serial lines. There are three types of organization of data transmission lines: single UTP channels (Ultra-thin Pipe), dual (“thin”) TP channels (Thin Pipe) and quad (“thick”) FP channels (Fat Pipe). Each channel provides for operation in both full-duplex and half-duplex modes. The maximum bit rate for each wire pair provided by the standard is 6 Gbps.

Conclusion

The desire to increase the range of action led to the fact that radar, like many other areas of technology, survived the era of "gigantomania". More and more powerful magnetrons were created, antennas of ever larger sizes, mounted on giant turntables. The power of the radar has reached 10 or more megawatts per pulse. It was already physically impossible to create more powerful transmitters: resonators and waveguides could not withstand the high intensity of the electromagnetic field, and uncontrolled discharges occurred in them. Data also appeared on the biological danger of highly concentrated radar radiation: people living near the radar station had diseases of the hematopoietic system, inflamed lymph nodes. Over time, standards appeared for the maximum flux density of microwave energy that is permissible for human work (up to 10 mW/cm2 is allowed for a short time).

New requirements for radar have led to the development of completely new technology, new principles of radar. At present, on modern radars, the pulse sent by the station is a signal encoded according to a very complex algorithm (the most common is the Barker code), which makes it possible to obtain data of increased accuracy and a number of additional information about the observed target. With the advent of transistors and computer technology, powerful megawatt transmitters are a thing of the past. They were replaced by complex medium-power radar systems combined by means of a computer. Thanks to the introduction of information technology, synchronous automatic operation of several radars became possible. Radar systems are constantly being improved, finding new areas of application. However, there is still a lot of unexplored, so this area of science will be of interest to physicists, mathematicians, radio engineers for a long time; will be the object of serious scientific work and research. The development of modern science and technology is impossible to imagine without the use of radar, which is used in space exploration, and in the navigation of aircraft and ships, and in military technology (for target detection and missile guidance).

Bibliography

1. https://ru.wikipedia.org/wiki/Radar/

2. http://www.twirpx.com/file/989969/

3. http://learndsp2012.tom.ru

Primary processing

The essence: the selection of targets against the background of noise and interference, identification of "friend or foe"

Input: radar signal.

Output: target position, angular size, azimuth and distance.

Carried out: by a primary processing device located in the radar station; earlier - points for processing radar information.

Secondary processing

Essence: identification of targets during several radar scan cycles; calculation of direction and speed; combating primary processing errors - double targets, random bursts and temporary disappearances of targets.

Input: targets obtained by primary processing.

Carried out: manual escort operator; point for processing radar information (at the level of the radar company) semi- and automatically.

Tertiary processing

Essence: comparison of information received from several sources.

Input: target traces obtained as a result of secondary processing; radar coordinates.

Output: target traces obtained taking into account the transfer of the target from one radar to another, the accuracy of different sources, etc.

Conducted: at the level of the radio engineering battalion and above; manually (by a tablet operator), semi-automatically or automatically by ACS.

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Aviation combat operations management systems, in addition to the tasks discussed above for processing information from one radar, solve another problem that is associated with combining information about targets received from several radars or primary radar processing posts, and creating a general picture of the air situation.

The processing of radar data coming from several sources was agreed to be called tertiary information processing (TOI).

In view of the fact that radar coverage areas or areas of responsibility of posts usually overlap, information about the same target can be received simultaneously from several stations. Ideally, these marks should overlap one another. However, in practice, this is not observed due to systematic and random errors in the measurement of coordinates, different location times, and also due to errors in recalculating coordinates between the points of standing of the source and receiver of information.

The main task of tertiary processing is to solve the problem,

how many targets are actually in the area of responsibility. To solve this problem, you must perform the following operations:

Collect reports from sources;

Bring marks to a single coordinate system and a single reference time;

Set whether the marks belong to the targets, i.e. solve the problem of identifying marks;

Perform information consolidation.

To solve these problems, all the characteristics of the goals are used. Tertiary processing devices are implemented on specialized computers with full automation of all operations performed. However, sometimes, to simplify automatic devices, some TOI operations can be performed on commands and with the participation of an operator. In particular, the identification and enlargement operations are performed in this way.

Tertiary processing is the final step in obtaining information about the air situation.

Statement of purpose It is customary to call information containing information about the location of targets, about their characteristics, issued from sources via communication channels for its further processing and use.

A task collection of reports is to receive as much information as possible with minimal loss.

Each incoming report must be processed, which takes some time. Let at the moment of receipt of the report, the processing of the previous report is performed. In this case, the received message can either leave the system unprocessed, or wait in line for service until the system is free, or wait for processing for a strictly limited time. In accordance with this, all queuing systems are divided into systems with failures, systems with waiting, and systems with limited waiting (mixed type). In practice, mixed-type systems with a waiting time selected from the best processing condition have become widespread.

Target coordinates are measured in the coordinate system of the detected radar, therefore, when transmitting data to the TOI point, it is necessary recalculate them to the point of standing of the information receiver. Geodetic, polar or rectangular coordinate systems can be used as a single coordinate system. The most accurate is the geodesic, but the calculations in it are complex. Therefore, it is used only when the sources and receivers of information are at large distances from each other and the curvature factor of the Earth is large. In other cases, polar or rectangular coordinate systems are used with height correction. Calculations in these systems are quite simple and acceptable for solving a number of practical problems.

In ACS, the transmission of target coordinates is usually carried out in a rectangular coordinate system. The processing station also uses a rectangular system. Therefore, the task is reduced to converting the rectangular coordinates of the targets relative to the source point into rectangular coordinates relative to the station of the processing point.

The marks obtained at the TOI point from different sources are given to a single reference time. A single time is necessary in order to determine the position of the processed marks as of any one moment in time. This operation greatly simplifies the task of identifying marks.

The coordinates of the marks are brought to a common time by determining for each time mark an extrapolation relative to a given point of comparison. Considering the relatively high rate of information update, it is advisable to take the hypothesis of uniform and rectilinear change in coordinates when extrapolating.

All radar data sources process information autonomously and independently of each other. Due to the overlap of areas of responsibility, reports may contain duplicate reports received from several sources for the same purpose.

In the process identification marks targets a decision is made that:

How many targets are there in reality if they are reported from several sources;

How the received reports are distributed by target.

Usually identification is performed in two stages. First, a rough identification or comparison of marks is made, and then a distribution of marks is carried out, which makes it possible to make a more accurate decision on the identification.

The comparison step is based on the assumption that reports from the same target should contain the same characteristics. Because of this, the decision on the identity of marks is made on the basis of and comparison of characteristics. However, in reality, due to various errors, there is no complete coincidence of characteristics. As a result, there is an uncertainty expressed by two competing hypotheses:

1. The hypothesis assumes that marks from the same target,

although there was a mismatch.

2. The hypothesis assumes that the marks are from different targets, so there was a mismatch.

The decision to choose one or another hypothesis is made on the basis of an estimate of the magnitude of the discrepancy and the use of the criterion for the minimum decision error.

At the distribution stage, to group marks by individual targets, signs of their belonging to information sources and numbering of targets in the system of these sources are used. The rules for logical grouping of marks in accordance with the belonging of target reports to information sources are formulated as follows.

1. If marks from the same source are received in the area of permissible deviations, then the number of targets is equal to the number of marks, since one station at the same time cannot issue from

multiple marks on the same target.

2. If one mark is received from each source in the area of permissible deviations, then it is considered that these marks refer to the code and the same purpose.

3. If an equal number of marks are received from each station, then it is obvious that the number of targets is equal to the number of marks received from one station, since it is unlikely that, within a small area, a station detects only its own targets and does not detect a target observed by a neighboring station.

4. If an unequal number of marks were received from several sources, it is assumed that the source from which the largest number of marks was received gives the most probable situation. In this case, the total number of targets is determined by the number of marks received from the specified source.

Thus, the processing of reports in a group consists in grouping marks from several sources to one goal. This problem is solved relatively simply when using the first and second rules, and much more difficult when using the third and fourth ones.

According to the hypothesis of the third rule, we have two goals, each of which refers to one report from each source. It is necessary to determine which pairs of marks belong to each target. The most plausible variant is chosen as a result of comparing the sums of squared distances between the marks. The combination for which this amount is minimal is accepted.

The given rules for comparing and distributing marks are not the only ones, and depending on the required accuracy, they can be complicated or simplified.

After identification, information about the target is expressed by a group of marks received from several sources. To form one mark with more accurate characteristics, the coordinates and parameters of the trajectory are averaged.

The simplest way to average is to calculate the arithmetic mean of the coordinates. This method is quite simple, but it does not take into account the accuracy characteristics of information sources. It is more correct to average the marks of the targets, taking into account the coefficient of the weight of the marks, and the coefficient is selected depending on the accuracy of the source. And finally, as an average, you can take the ordinates of the mark obtained from one source, if there is evidence that this source provides the most accurate information.

Enlargement (grouping) of target marks is carried out at those processing points where information on each target is not required or the density of receipt of marks from the targets turns out to be higher than the calculated throughput. Grouping is usually done at the highest levels of the management system.

Grouping is carried out in the same ways as identification, and is carried out on the basis of the proximity of the coordinate descriptions of the grouped objects. To do this, a gate is formed according to the coordinates that are assigned as characteristic for a group of targets. The coordinates of the center of the gate apply to the entire group. It is usually done so that the center of the gate coincides with the mark of the head target in the group. The dimensions of the strobe are determined based on their navigational and tactical requirements. A semi-automatic upscaling method is usually used, which includes the following main steps:

1. Selection of compact groups of targets based on the proximity of coordinates x, y, H. The operator visually determines a compact group of targets by coordinates, selects the main target, assigns one of the enlargement gates and enters the number of the gate and the main target into the computer. Based on this information, the computer completes the process of selecting a compact group.

2. Selection within selected groups by speed. A goal remains a part of an enlarged goal if:

where are the speed components of the head target; is the speed selection threshold.

3. Determining the characteristics of the enlarged goal. The enlarged goal is assigned a quantitative composition, and a generalized sign of action is formed.

4. Correction of the operator's decision. Due to the fact that the situation in the air changes, it is possible to correct the data of the enlarged target by enlarging it, downscaling, downscaling or upscaling.

5. Accompanying the enlarged goal. This operation is carried out automatically by the computer. In this case, the coordinates are corrected, the choice of the main target is ensured when the information of the old main target disappears.

Thus, during the TOI process, reports are collected from sources, the marks are brought to a single coordinate system and a single reference time, the marks belong to the targets (marks are identified) and the information is aggregated.

Conclusion

1. Operations performed during primary processing can be performed by the radar independently.

2. If during primary processing useful information is extracted from a mixture of signal and noise based on the statistical difference in the structure of the signal and noise, then secondary processing, using differences in the patterns of appearance of false marks and marks from targets, should ensure the selection of trajectories of moving targets.

3. The trajectory of the target movement is represented as a sequence of polynomial sections with different coefficients and degrees of polynomials, i.e. the processing system must be rebuilt in accordance with the nature of the movement of each target.

4. In the process of TOI, reports are collected from sources, the marks are brought to a single coordinate system and a single reference time, the marks belong to the targets (marks are identified) and the information is aggregated.

On self-preparation, it is necessary to prepare for the control work the following questions:

1. Purpose and content of primary processing of radar information.

2. Purpose and content of secondary processing of radar information.

3. Determining the parameters of the movement of targets in the process of secondary processing of radar information.

4. Extrapolation of marks in the process of secondary processing of radar information.

5. Continuation of the trajectory of movement in the process of the goal of secondary processing of radar information.

6. Purpose and content of tertiary processing of radar information.

7. Collection of reports in the process of the goal of tertiary processing of radar information.

8. Reduction of target marks to a single coordinate system and a single reference time in the process of targeting tertiary processing of radar information.

9. Identification of target marks in the process of the target of tertiary processing of radar information.

10. Consolidation of information in the process of TOI.

Introduction

The main task of radar is to collect and process information about the objects being probed. In multi-position ground-based radars, as is known, the entire processing of radar information is divided into three stages.

Primary processing consists in detecting the target signal and measuring its coordinates with the appropriate quality or errors.

Secondary processing provides for the determination of the parameters of the trajectory of each target from the signals of one or a number of MPRLS positions, including the operations of identifying target marks.

At tertiary processing the parameters of the target trajectories obtained by various MPRLS receivers are combined with the identification of the trajectories.

Therefore, consideration of the essence of all types of processing of radar information is very relevant.

To achieve our goals, consider the following questions:

1. Primary processing of radar information.

2. Secondary processing of radar information.

3. Tertiary processing of radar information.

This training material can be found in the following sources:

1. Bakulev P.A. Radar systems: Textbook for universities. – M.:

Radio engineering, 2004.

2. Belotserkovsky G.B. Fundamentals of radar and radar

devices. - M.: Soviet radio, 1975.

Primary processing of radar information

To automate aviation management processes, it is necessary to have

comprehensive and continuously updated information on the coordinates and characteristics of air targets. This information in automated control systems (ACS) is obtained using the means included in the subsystem for collecting and processing radar information (RLI), namely: posts and processing centers for RLI, aviation systems for radar patrol and guidance. Radars are the main means of obtaining information about air targets. The process of obtaining information about objects in the radar visibility zone is called processing RLI.

Such processing allows obtaining data on the coordinates of the target, parameters of its trajectory, location time, etc. The totality of information about the target is conditionally called mark. The marks, in addition to the above data, may include information about the number of the target, its nationality, quantity, type, importance, etc.

Signals that carry the information necessary for the operator are called useful, but they, as a rule, are necessarily superimposed with interference that distorts the information. In this regard, in the process of processing, the tasks of isolating useful signals and obtaining the necessary information under interference conditions arise.

Information processing is based on the existence of differences between the useful signal and the interference. The whole process of radar image processing can be divided into three main stages: primary, secondary and tertiary processing.

At the stage primary processing Radar radar detects the target and determines its coordinates. Primary processing is carried out one by one, but more often by several adjacent range sweeps. This is enough to detect the target and determine its coordinates. Thus, the primary processing of radar data is the processing of information for one period of the radar survey. The composition of the primary processing of radar data includes:

Detection of a useful signal in noise;

Determination of target coordinates;

Coding target coordinates;

Assigning numbers to goals.

Until recently, this task was solved by the radar operator. But at present, in real conditions of tracking many targets moving at high speeds by indicators, a human operator is not able to assess the diversity of the air situation using only a visual method. In this regard, the problem arose of transferring part or all of the functions of a human operator in the processing of radar data to computing tools that were created at the facilities of automated control systems for aviation.

Primary processing RI begins with the detection of a useful signal in noise. This process consists of several stages:

Single signal detection;

Signal packet detection;

Formation of a complete package of signals;

Determining the range to the target and its azimuth.

All these stages are implemented using optimal algorithms based on the criteria for minimizing decision errors and measurement results.

Thus, the operations performed during the primary processing can be performed by the radar independently.