And detecting the work of a police radar (speed indicator) and warning the driver that the traffic police inspector instrumentally monitors compliance with the Rules of the Road (SDA).

Rules traffic speed limits are set on highways, for violation of traffic rules, a driver may be fined or administratively punished (for example, deprivation of a driver’s license). Car drivers, wishing to be informed about the work of the traffic police and / or in an effort to avoid punishment for intentional or unintentional traffic violations, install a radar detector on their cars. The radar detector is a passive device that detects police radar exposure and alerts the driver (exposure warning system).

Design features

The simplest radar detectors and radar detectors are installed behind the windshield, on the interior rear-view mirror or in the car, connected to the on-board network (12 volts) through the cigarette lighter. More complex non-removable models for installation require the involvement of specialists. These devices are classified:

• By execution: built-in and non-built-in;
• According to the controlled frequency bands on which police radars operate: X, Ku, K,, Laser;
• By radar mode: OEM , Ultra-X, Ultra-K (K-Pulse)/(Smartscan™), Instant-On, POP™, HYPER-X™, HYPER-K™;
• By coverage angle (in degrees): all directions, oncoming, passing.

(Instruments with a 360° response width can detect speed-monitoring radars at an angle to the direction of travel and on receding vehicles.)

• If possible, binding to GPS, Glonass coordinates.

Radar detectors can respond to interference generated by power lines, electric transport (tram, trolleybus, electric locomotives), so protection against false alarms is built into many models.

The "radar jamming" design feature, or distorting the intruder's speed determined by the police radar, which actually makes it a "radar suppressor" is prohibited in all countries. In addition, some radar detectors can detect laser speed meters (lidars) as well as VG-2 systems (devices that detect radar detectors).

In 2010-2012, the STRELKA-ST complex of video recording of offenses, popular with the Russian traffic police, was not detected by most radar detectors. In 2012, there were only a few models on sale (this functionality was announced by all manufacturers). Today there is not a single radar detector that would not be able to warn in advance about "STRELKA-ST" and "STRELKA-M".

At the end of the summer of 2017, the newest mobile speed meter on a wheelbase appeared in the vastness of the Russian Federation, called "OSCON-SM", which is still confidently determined by literally a few devices costing from 40 thousand rubles.

Features of the use of radar detectors and radar detectors

The use of radar detectors and radar detectors is regulated by law.

In some states and federal associations, local laws prohibit the use of laser/radar detectors. Before using the device, make sure that its use is permitted in your area. Throughout the territory Russian Federation, Ukraine and Belarus, the use of radar detectors is not prohibited.

Laws of other countries

• Austria : Use prohibited. Violators are subject to a monetary fine, and the device is confiscated.
• Azerbaijan: Radar detectors are banned, there is no ban on the use of a radar detector.
• Albania: There is no prohibition on transport and use.
• Belarus: Radar detectors are illegal in Belarus. But the traffic police has nothing against radar detectors, considering them even to some extent useful for road safety.
• Belgium: Prohibited the manufacture, importation, possession, offer for sale, sale and free distribution of equipment that indicates the presence of traffic control devices and interferes with their functioning. Violation threatens imprisonment from 15 days to 3 months, or a monetary fine is charged. In the event of a repeated violation, the fine is doubled. In any case, the device is removed and destroyed.
• Bulgaria: There is no general ban. Use is permitted as long as it does not interfere with the speed measurement
• Hungary: Possession, use while driving, and advertising of radar detectors is prohibited. Failure to comply will result in a fine and the removal of the device.
• Denmark: It is prohibited to equip a vehicle with equipment or separate parts configured to receive electromagnetic waves from police devices configured to control speed or interfere with the operation of these devices. Violation is subject to a monetary fine.
• Spain : prohibited.
• Latvia : Use prohibited. When selling, there are no restrictions. However, upon detection, a fine is imposed, the equipment is confiscated.
• Lithuania: Use prohibited. It is possible to levy a fine and confiscate equipment.
• Luxembourg: Imprisonment from 3 days to 8 years is possible, as well as the collection of a monetary fine and the seizure of equipment.
• Netherlands: no ban on use.
• Norway: No ban on use, but some minor restrictions.
• Poland : Not allowed to be used or transported in operational condition. Transportation is allowed only when the device is declared unfit for use (for example, packed). In case of violation, a monetary fine will be charged.
• Romania: There is no ban on use. This position is being discussed.
• Turkey: There is no ban on use.
• Finland: police use on regular and freelance vehicles for catching violators. 95% of radars are based on the Ka-band, but sometimes the K-band is used, and very rarely laser. There are no radars based on the X and Ku bands. Also in Finland, Gatso type traps are sometimes used on new roads, but these are not radars using radio waves, but GPS direction finders using sensors installed on the median strip of the road. To track such devices, other types of detectors are needed.
• France
• Czech Republic: no ban on use. This position is still under discussion.
• Switzerland: Offering for sale, importation, purchase, sale, installation, use and transportation of instruments that indicate the presence of radars are subject to a monetary penalty. Then the device and the car in which it is located are removed.
• Sweden: There is a ban on production, transfer, possession and use. Violation threatens with the removal of the device, a fine or imprisonment for up to 6 months.
• Germany: in this respect one of the most loyal countries. The police repeatedly carried out special actions, as a result of which radar detectors were given to motorists. For safety reasons, road services have installed so-called "false radars" on the most dangerous sections of roads - devices that imitate the signal of a traffic radar. When the radar detector is triggered, the driver reduces the speed, which accordingly reduces the accident rate. Since 2002, use has been banned. When selling or owning there are no restrictions. However, if the device is found to be installed and ready for use, a monetary fine (75 Euros) and one point in the penalty register will be imposed, and the equipment will be confiscated.
• Estonia: Radar detectors and radar detectors are prohibited. The fine reaches 400 euros, and the device is confiscated. Almost all police crews are equipped with radar detectors and radar detectors. So in 2012 a record was set recent years: then 628 radar detectors were detected in Estonia, mostly from visiting foreigners

The presence of a radar detector in the car sometimes avoids unpleasant contacts with traffic inspectors and can positively influence the self-discipline of drivers, thereby increasing traffic safety.

Traffic police inspectors, knowing that drivers often carry a radar detector in their car, use a different tactic of “hunting” for traffic offenders. The policeman hides in an "ambush" and turns on his radar only for a very short time, "in the forehead" of an approaching car. The violating driver has no chance to slow down in advance in order to avoid punishment. But the driver can stop (the range of the radar is 300 meters) and stand for 10 minutes: after this interval, the readings of the device are automatically reset to zero. Also, a traffic police officer is unlikely to be able to prove that it is your speed on the device. We can say that this method of avoiding punishment is not effective. Recently, all traffic police radars must be equipped with photo or video recording devices, and therefore, no matter how much you stand, waiting for the radar to reset, nothing will come of it. Your photo or even video will be on the computer in the police car

Tags: Radars, radar device, the principle of operation of the radar, examples of the use of radars

Radars

Radar is a device for detecting and locating objects in space by radio waves reflected from them; radar.

The name of this radar device "radar" (Radar) comes from the abbreviation of its full name in English - Radio Detection And Ranging (radio detection and ranging).

Basic principles of radar operation

Can be described in the following way the principle by which the radar works: very similar to the principle of reflecting a sound wave. If you shout in the direction of a sound-reflecting object (such as a mountain gorge or a cave), you will hear an echo. If you know the speed of sound in air, you can then estimate the distance and the general direction and direction of the object. The time it takes for the echo to return can be roughly converted to distance if you know the speed of sound. The radar uses electromagnetic pulses. High frequency energy is measured by the radar and reflected from the observed object. Some small part of this reflected energy is returned back to the radar. This reflected energy is called an ECHO, just like in sound terminology. The radar uses this echo to determine the direction and distance to the reflecting object.

As follows from this definition, radars are used to detect the presence of a target (object of detection) and determine its position in space. The abbreviation also implies the fact that the quantity measured is usually the distance to the object. On fig. 1. shows a simplified principle of operation of the simplest radar. The radar antenna irradiates the target with a microwave signal, which is then reflected from the target and "captured" by the receiving device. The electrical signal picked up by a radar receiving antenna is called an "echo" or "response". The radar signal is generated by a powerful transmitter and received by a special highly sensitive receiver.

Signal processing algorithm

The operation algorithm of the simplest radar can be described as follows:

• The radar transmitter emits short, powerful microwave energy pulses.
• The switch (multiplexer) alternately switches the antenna between the transmitter and receiver so that only one required antenna is used. This switch is necessary because the transmitter's powerful pulses would destroy the receiver if the power were applied directly to the receiver's input.
• The antenna transmits the transmitter signals into space with the required distribution and efficiency. This process is applied in a similar way when receiving
• The transmitted pulses are radiated into space by the antenna in the form of an electromagnetic wave that travels in a straight line at a constant speed and will then be reflected from the target
• The antenna receives backscattered signals (so-called echoes)
• When receiving, the multiplexer sends weak echo signals to the input of the receiver
• Ultra-sensitive receiver amplifies and demodulates received microwave signals and outputs video signals
• The indicator provides the observer with a continuous graphical picture of the position of relative radar targets.

All targets produce the so-called diffuse reflection, i.e. the signal is usually reflected in a wide range of directions. This reflected signal is also called "scatter" or backscatter, which is the term given to reflections of the signal in the opposite direction of the incident beam.

Radar signals can be displayed on both the traditional Plane Position Indicator (PPI) and more modern (LCD, plasma, etc.) radar display systems. The PPI screen has a rotating radar vector at the origin that represents the direction of the antenna (azimuth of the targets). It usually depicts a picture of the area under study in the form of a map of the area covered by the radar beam.

Obviously, most of the functions of the simplest radar are time dependent. Time synchronization between the radar transmitter and receiver is required for distance measurements. Radar systems emit each pulse during the transmission time (or pulse duration τ), wait for echoes to return during the "listening" or rest time, and then emit the next pulse, as shown in Fig. 2.

The so-called synchronizer coordinates in time the synchronization process for determining the distance to the target and provides synchronization signals for the radar. It simultaneously sends signals to the transmitter, which sends the next new pulse, and to the indicator and other associated control circuits.

The time between the start of one pulse and the start of the next pulse is called the period or pulse interval (PRT) and PRT = 1/PRF.

Here, the pulse repetition frequency (PRF) of a simple radar system is the number of pulses that are transmitted per second. The frequency of transmission of pulses significantly affects the maximum distance that can be displayed, which we will show below.

The main function of the radar is to measure the distance

The distance to a stationary or moving target (object) is determined from the transit time of the high-frequency transmitted signal and the propagation velocity (c0). The actual distance of the target from the radar is usually referred to as "slant range" - it is some line in the field of view between the radar and the object being illuminated, while the distance "on the ground" is the horizontal distance between the emitter and its target and its calculations require knowledge of the height of the target. As the waves travel to and from the target, the physical round-trip time of the radar beam is halved to give the time it takes for the wave to reach that target. Therefore, the following formula is usually used for calculations:

Where R– slant range; t delay– the time required for the signal to travel to the target and back; from 0 is the speed of light (approximately 3 × 10 8 m/s).

If the corresponding transit time ( t delay) is known, then the distance R between target and radar can be easily calculated using this expression.

One practical problem in determining distance accuracy is how to unambiguously determine the distance to a target if the target returns a strong echo. This problem arises because pulsed radars typically transmit a train of pulses. The radar receiver measures the time between the leading edges of the last transmitted pulse and the echo pulse. In practice, it often happens that an echo will be received from the target at a considerable (large) distance after the transmission of the second transmission pulse.

In this case, the radar will determine the "wrong" time interval and, as a result, the wrong distance. The measurement process assumes that the pulse is associated with the second transmitted pulse and shows a significantly smaller distance to the target compared to the actual distance. This is called "distance ambiguity" and occurs when there are large targets at distances longer than the pulse repetition time. The pulse repetition time determines the maximum "single digit" distance. To increase the value of the "one-digit" distance, it is necessary to increase the PRT (which means - to reduce the PRF).

Echoes occurring after the receive time may be detected: – either at the transmit time, where they are not taken into account because the radar is not ready to receive at that time, – or at the next receive time, when they can lead to an error measurements. The area of ​​unambiguous determination of the range of the radar can be determined using the formula:

R unamb = RPT - τ ∙ c 0 2

The numerical value of the radar pulse repetition period (PRT) used is extremely important in determining the maximum distance, as the return time from the target, which exceeds the PRT of the radar system, manifests itself at incorrect positions (distances) on the radar screen. Reflections that appear at these "wrong" distances are considered as secondary echoes in time. In addition to the problem of the zone for unambiguously determining the range of distant targets (objects), there is also the problem of detecting objects at a minimum distance from the radar. It is known that when the leading edge of the echo pulse falls inside the transmit pulse, it is impossible to accurately determine the time of the "circular" passage. Minimum detectable distance ( Rmin) depends on the momentum of the transmitters at τ and multiplexer recovery time t recovery in the following way:

Runamb = τ - t recovery ∙ c 0 2

Since the radar receiver does not receive a signal until the end of the transmission pulse, it is necessary to disconnect it from the transmitter during transmission to avoid damage. In this case, the "echo" pulse comes from a very close target. Note that targets at a pulse-width equivalent distance from the radar are not detected. For example, a typical value for a pulse width of 1 µs for radar typically corresponds to a minimum detectable distance of 150 m, which is generally acceptable. However, "long" pulse radars have the disadvantage of a minimum distance, in particular pulse compression radars, which can use pulse durations in the order of tens or even hundreds of microseconds. Typical pulse duration τ is typically: – air defense radar: up to 800 µs (minimum distance 120 km); – civil airport air surveillance radar 1.5 µs (minimum distance 250 m); – airborne radar for detecting the movement of an object on the surface: 100 ns (minimum distance 25 m). Determining the direction of movement of the target (object) is another important function of the radar.

Radar specialists often use the term **azimuth**, the direction to the target, which is determined by the directivity of the radar antenna. Directivity, sometimes referred to as "direction gain", is the ability of an antenna to concentrate transmitted energy in one particular direction. Accordingly, such an antenna with high directivity is called a directional antenna. By measuring the direction in which the antenna is pointed when receiving an echo, the coordinates of the target can be determined. The accuracy of the angle measurements is usually determined by the directivity, which is a certain function of the geometric size of the antenna. The “true” bearing of a radar target is the angle between true north and some notional line indicating the direction to the target. This angle is usually measured in the horizontal plane and clockwise from north. The azimuth angle to the radar target can also be measured clockwise from the center line of the radar carrier ship or aircraft and is referred to in this case as relative azimuth. In particular, fast and accurate transmission of information in azimuth between the radar turntable with an antenna mounted on it and information screens is of great practical importance for various servo systems of modern electronic equipment. These servo systems are used in older classical radar antennas and ballistic missile launchers and operate with instruments such as rotary torque sensors and rotary torque receivers. With each rotation of the antenna, the encoder sends out many pulses, which are then counted in the indicators. Some radars operate without (or with partial) mechanical movement. Radars of the first group use electronic phase scanning in azimuth and / or elevation (antennas with a phased antenna array).

Target elevation angle

The elevation angle is the angle between the horizontal plane and the line of sight, measured in the vertical plane. The elevation angle is usually described using the letter ε. The elevation angle is always positive above the horizon (elevation angle 0), and negative below the horizon (Figure 4.).

A very important parameter for radar users is the height of the target above the ground (altitude), which is usually denoted by the letter H. The actual distance above sea level is considered the true altitude (Fig. 5.a). Altitude can be calculated using distance R and elevation angle ε, as shown in fig. 5.b., where:

• R– slant distance to the target
• ε – measured elevation angle
• r e– equivalent ground radius

However, in practice, as is known, the propagation of electromagnetic waves is also subject to the effect of refraction (the transmitted radar beam is not a straight line of the side of this triangle, it is bent), and the amount of deviation from a straight line depends on the following main factors: – transmitted wavelength; – barometric pressure of the atmosphere; – air temperature and – atmospheric humidity. Target accuracy is the degree of agreement between the estimated and actually measured position and/or speed of the target in this moment time and its actual position (or speed). The accuracy of radio navigation performance is usually represented as a given statistical measure of "system error". It should be said that the specified value of the required accuracy represents the uncertainty of the recorded value relative to the true value and actually shows the interval in which the true value lies at the specified probability. A generally recommended level of this probability is 9–10%, which corresponds to about two standard deviations of the mean for a normal Gaussian distribution of the variable being measured. Any residual offset must be small compared to the stated accuracy requirement. The true value is that value which, under operating conditions, accurately characterizes the variable to be measured or observed over the required characteristic time interval, area and/or volume. Accuracy should not "conflict" with another important parameter - the resolution of the radar.

Radar Antenna Gain

Usually this radar parameter is a known value and is given in its specification. In fact, this is a characteristic of the ability of the antenna to focus the outgoing energy in a directional beam. Its numerical value is determined by a very simple relation:

G = maximum radiation intensity average radiation intensity

This parameter (antenna gain) describes the degree to which the antenna concentrates electromagnetic energy in a narrow angled beam. Two parameters related to antenna gain are the direction gain of the antenna and directivity. Antenna gain serves as a measure of performance relative to an isotropic source with an isotropic antenna directivity of 1. The power received from a given target is directly related to the square of the antenna gain when that antenna is used for both transmit and receive. This parameter characterizes the antenna gain - the coefficient of increase in the transmitted power in one desired direction. It can be noted that in this respect, the reference is an "isotropic" antenna, which transmits signal power equally in any arbitrary direction (Fig. 6).

For example, if a focused beam has 50 times the power of an omnidirectional antenna with the same transmitter power, then the directional antenna has a gain of 50 (17 decibels).

Antenna aperture

As noted above, usually in the simplest radars, the same antenna is used during transmission and reception. In the case of transmission, all the energy will be processed by the antenna. In the case of reception, the antenna has the same gain, but the antenna receives only a portion of the incoming energy. The "aperture" parameter of an antenna generally describes how well that antenna can receive power from an incoming electromagnetic wave.

When using an antenna as a receiving signal, the aperture of the antenna can, for ease of understanding, be represented as the area of ​​a circle built perpendicular to the incoming radiation, when all the radiation passing within the circle is output by the antenna to the matched load. Thus, incoming power density (W/m2) × aperture (m2) = incoming power from the antenna (W). Obviously, the antenna gain is directly proportional to the aperture. An isotropic antenna usually has an aperture of λ2/4π. An antenna with gain G has an aperture of Gλ2/4π.

The dimensions of the designed antenna depend on its required gain G and/or the wavelength used λ as an expression of the frequency of the radar transmitter. The higher the frequency, the smaller the antenna (or higher gain for equal sizes).

Large "dish-shaped" radar antennas have an aperture almost equal to its physical area and gain typically between 32 and 40 dB. Changing the quality of the antenna (irregularity of the antenna, deformations, or the usual ice formed on its surface) has a very large effect on the gain.

Noise and echoes

The minimum discernible echo is defined as the strength of the wanted echo at the receiving antenna that produces a discernible target mark on the screen. The minimum distinguishable signal at the input of the receiver provides the maximum detection distance for the radar. For each receiver, there is a certain amount of receive power at which the receiver can operate at all. This lowest operating received power is often referred to as MDS (Minimum Distinguishable Signal). Typical MDS values ​​for a radar range from 104 to 113 dB. The numerical values ​​of the value of the maximum target detection range can be determined from the expression:

R max = P tx ∙ G 2 ∙ λ 2 ∙ σ t 4π 3 ∙ P MDS ∙ L S 4

The term "noise" is also widely used by developers and users of radar technology. The numerical value of MDS depends primarily on the signal-to-noise ratio, defined as the ratio of the useful signal energy to the noise energy. All radars, as they are all-electronic equipment, must operate reliably in the presence of a certain level of noise. The main source of noise is called thermal noise, and it is caused by the thermal motion of electrons.

In general, all types of noise can be divided into two large groups: external atmospheric or cosmic noise and internal (receiver noise - generated internally in the radar receiver). The overall (integral) sensitivity of the receiver largely depends on the level of inherent noise of the radar receiver. receiver with low level noise floor, as a rule, is developed using special design and components, which are located at the very beginning of the path. Designing a receiver with very low noise performance is achieved by minimizing the noise figure in the very first block of the receiver. This component is typically characterized by low noise performance with high gain. For this reason, it is commonly referred to as a "Low Noise Preamplifier" (LNA).

A false alarm is “an erroneous decision to detect a target by a radar, caused by noise or other interfering signals that exceed the detection threshold.” Simply put, this is an indication of the presence of a target by a radar when there is no real target. False signal intensity (FAR) is calculated using the following formula:

FAR = number of decoys number of range cells

Therefore, another parameter is used - the probability of target detection, which is defined as follows:

P D = target detection all possible target marks ∙ 100%

Classification of radar devices

Depending on the function performed, radar devices (RLD) are classified as follows (Fig. 7) .

Two large groups of radars can be singled out at once, differing in the type (kind) of the final information display device used. These are RLC with imaging and RLC without imaging. Imaging radar forms a picture of the observed object or area. They are commonly used to map the earth's surface, other planets, asteroids, other celestial bodies, and to categorize targets for military systems.

Non-imaging radars usually measure only in a linear one-dimensional representation of the image. Typical representatives of a non-imaging radar system are speed meters and radar altimeters. They are also called reflection meters because they measure the reflection properties of the object or area being observed. Examples of non-imaging secondary radars are car anti-theft systems, room protection systems, etc.

All varieties of radars in foreign literature are divided into two large groups "Primary Radars" (primary radars) and "Secondary Radars" (secondary radars). Consider their differences, features of organization and application, using the terminology of the main source used below.

Primary Radars

The primary radar itself generates and transmits high-frequency signals that are reflected from targets. The resulting echoes are received and evaluated. Unlike the secondary radar, the primary radar emits and receives its own transmitted signal again as an echo. Sometimes the primary radar is equipped with an additional interrogator provided with the secondary radars to combine the advantages of both systems. In turn, Primary Radars are divided into two large groups - impulse (Pulses Radars) and wave (Continuous Wave). Pulse radar generates and transmits a high-frequency, high-power pulse signal. This pulse signal is followed by a longer time interval during which an echo can be received before the next signal is sent. As a result of processing, it is possible to determine the direction, distance and sometimes, if necessary, the height or height above sea level of the target based on the fixed position of the antenna and the propagation time of the pulse signal. These classic radars transmit very short pulses (to get good resolution by distance) with an extremely high pulse power (to obtain the maximum target recognition distance). In turn, all impulse radars can also be divided into two large groups. The first of these is pulsed radar using the pulse compression method. These radars transmit a relatively weak pulse with a long duration. Modulates the transmitted signal to obtain distance resolution also within the transmitted pulse using a pulse compression technique. Further, monostatic and bistatic radars are distinguished, representing the second group. The former are deployed in the same place, the transmitter and receiver are co-located, and the radar basically uses the same antenna for receiving and transmitting.

Bistatic radars consist of separate receiver and transmitter locations (at a considerable distance).

Secondary Radars

The so-called secondary radar is characterized in that the object using it, such as an aircraft, must have its own transponder (transmitting transponder) on board and this transponder responds to the request by transmitting a coded recall signal. This response may contain significantly more information than the primary radar can receive (eg altitude, identification code, or also any technical problems on board such as loss of radio communications).

Continuous wave radars (CW radars) transmit a continuous high frequency signal. An echo signal is also received and processed continuously. The transmitted signal of this radar is constant in amplitude and frequency. This type of radar usually specializes in measuring the speed of various objects. For example, this equipment is used for speed meters. A CW radar transmitting unmodulated power can measure speed using the Doppler effect, but it cannot measure the distance to an object.

CW radars have the main disadvantage that they cannot measure distance. To eliminate this problem, the frequency shift method can be used.

Classification and principal features of military radars

The whole variety of radars can be divided into types based on their areas of use.

Air defense radars can detect airborne targets and determine their position, course and speed over a relatively large area. The maximum distance for air defense radars can exceed 500 km, and the azimuth coverage is full circle in 360 degrees. Air defense radars are usually divided into two categories depending on the amount of information transmitted about the position of the target. Radars that provide only distance and bearing information are called two-dimensional or 2D radars. Radars that provide distance, azimuth, and altitude are called 3D or 3D radars.

Air defense radars are used as early warning devices, as they can detect the approach of enemy aircraft or missiles at long distances. In the event of an attack, early warning about the enemy is important for organizing a successful defense against the attack. Protection against aviation in the form of anti-aircraft artillery, missiles or fighters must have a high degree of readiness in time to repel an attack. Distance and azimuth information provided by air defense radars is intended for initial positioning of radars, tracking and fire control at a target.

Another function of an air defense radar is to direct a combat patrol aircraft to a position suitable for intercepting an enemy aircraft. In the case of aircraft control, information on the direction of the target's movement is obtained by the radar operator and transmitted to the aircraft either by voice to the pilot via a radio channel or via a computer line.

The main applications of air defense radars:

• long range early warning (including aerial target early warning)
• target acquisition and ballistic missile warning
• target height determination

Radar application

Radar is used for both military and civilian purposes. The most common civilian application is navigational aid for ships and aircraft. Radars installed on ships or at the airport collect information about other objects in order to prevent possible collisions. At sea, information is collected about buoys, rocks, etc. In the air, radars help aircraft land in conditions of poor visibility or malfunction. Radars are also used in meteorology, in forecasting weather conditions. Forecasters typically use them in conjunction with lidar (optical radar) to study storms, hurricanes, and other weather events. Doppler radar is based on the principle of the Doppler effect - that is, a change in frequency and wavelength for the observer (receiver) due to the movement of the radiation source or observer (receiver). By analyzing changes in the frequency of reflected radio waves, Doppler radar can track the movement of storms and the development of tornadoes.

Scientists use radar to track the migration of birds and insects, to determine the distance to the planets. Because it can show in which direction and how fast an object is moving, radar is used by police to detect speed violations. Similar technologies are used in sports such as tennis to determine pitch speed. Radar is used by intelligence agencies to scan objects. For military purposes, radars are mainly used as a search for targets and fire control.

Radars are now used quite widely. They are especially widely used in military equipment- no aircraft or ship is complete without a radar. And ground-based radars are common. Based on their testimony, controllers control the movement and landing of aircraft, they monitor the appearance of dangerous or suspicious objects on land and at sea. Ships also have a device called an echo sounder, which works on the principle of radar, only measuring the depth under the vessel.

Modern radars are capable of detecting targets hundreds of kilometers away. Entire networks created radar stations, which constantly "probe" the surface of the Earth in order to detect air and missile attacks. And for peaceful purposes, radars are also used - in space technology and in air transport, on ships and even on roads.

The discovery of radio waves gave us not only radio, television and mobile phones, but also the ability to "see" for hundreds and thousands of kilometers in any weather, on Earth and in space. And in conclusion - just interesting fact. The so-called "stealth aircraft" created using the "stealth" technology, of course, are not actually invisible. To the eye, they are ordinary planes, only of an unusual shape. And the outer skin of such an aircraft is designed so that the radar beam in any position is reflected anywhere, but not back to the radar. In addition, it is made of a special polymer that absorbs most of the radio signal. That is, the radar will not receive a reflected signal from such an aircraft, which means that it will not draw anything on its screen. Such is the technology war.

Overview of some other modern radar systems

Siemens VDO Automotive has been offering a system based on radar and vision sensors since 2003. To implement blind spot monitoring and lane change assistance, the Siemens VDO system uses a 24 GHz dual-beam radar sensor mounted on the rear bumper of the vehicle, which is both the ACU and the sensor as one component.

In 2003, Denso introduced two systems, ACC and Crash Prevention, both using millimeter-wave radar and a control unit (named vehicle distance ECU for ACC and pre-crash ECU, respectively).

Denso's 77 GHz radar can detect obstacles in a 20° horizontal plane with an accuracy of 0.5°. Relative speed detection range is ±200km/h (including stationary object detection), distance detection range is more than 150m.

Denso's radar-based pre-crash safety system automatically activates the passenger's seat belts and the vehicle's braking system. Denso developed this system in partnership with Toyota Motor Corporation. In new cars, this system was introduced in Japan as early as 2003, and in North America in 2004.

The ACC from TRW Automotive includes a 76 GHz AC20 radar sensor with FSK digital waveform, a digital processor and a controller. The radar sensor with a typical CAN interface uses a modular design based on MMIC. Distance measurements - in the range of 1–200 m with an accuracy of ± 5% or 1 m, speed measurements - in the range of ± 250 km / h with an accuracy of ± 0.1 km / h, angular measurement range of ± 6 ° with an accuracy of ± 0.3 °.

The maximum deceleration during ACC intervention in the control (brake system) is limited to a limit of 0.3 g. If more deceleration is required, driver intervention is required. The necessary braking power in TRW systems can also be provided by the Electronic Booster, VSC/ESP.

TRW's SPV/ACC can be extended with additional short range sensors (<50 м). Скоростной диапазон при этом может быть расширен до 0 км/ч, для осуществления функций, подобных Follow Stop (Follow Stop означает, что в ситуациях затора автомобиль следует за впереди идущей машиной, пока она не остановится, и автоматическую остановку хост-автомобиля, при этом возобновление движения осуществляется по нажатию кнопки водителем, в отличие от Stop&Go). Функциональность АУП и ПНУП осуществляется с дополнительными видеодатчиками. РКД от TRW предназначены также для поддержки других функций СПВ, например, мониторинга «мертвых зон».

Since the ACC is often too active in control, causing many drivers to turn off cruise control, the Eaton VORAD (Vehicle Onboard RADar) radar system was developed by the manufacturer to achieve minimal system intervention in control and is marketed mainly as a means of assisting the vigilant and conscientious driver.

The Eaton VORAD system consists of four main components: antenna assembly, central processing unit, driver's display, connecting harnesses.

The Eaton VORAD system includes a primary forward radar for monitoring vehicles in the frontal field of view and additional side radars for blind spot monitoring and other applications. Side sensors and side touch displays are supplied as options by the manufacturer. The radar signals from the operating system always determine the distance between objects in the front of the vehicle and the relative speed and serve to warn the driver of dangerous situations through visual and audible signals only (no video playback). In addition to many standard features, options such as Fog Mode (a visual warning on the display about the presence of objects within 150 meters), adjustment of the intensity of the display based on signals from the light sensor, simultaneous tracking of up to 20 objects in front, and others are provided.

The VORAD system also supports two special modes - Blind Spotter and Smart Cruise.

In Blind Spotter mode, an optional side sensor, including a radar transmitter and receiver mounted on the side of the vehicle, detects moving or stationary objects from 0.3 to 3.7 m away from the vehicle.

In SmartCruise mode, the vehicle maintains a set distance from the vehicle in front.

Delphi introduced to the automotive market its 24 GHz UWB Forewarn Back-up Aid system integrated radar with CAN interface, designed to provide reverse assistance functions, including automatic braking upon identification of a moving or stationary obstacle. The principle of operation of the system is CW (not Doppler).

Improvements include an integrated dual receiver and a visual range indicator. The dual receiver increases the measurement range to 6 m with typical reversing speeds in the range of 4.8-11.3 km/h, while extending the coverage around the corners of the vehicle.

Delphi has also developed other systems for frontal and side detection of objects. Thus, the 24 GHz side detector of the RKD in the Delphi Forewarn Radar Side Alert system warns the driver about the appearance of objects in adjacent lanes within 2.4–4 m. The frontal object detection system uses a multifunctional 77 GHz RDD for detection and classification objects within a range of up to 150 m. Forewarn Smart Cruise Control, Forward Collision Warning and Collision Mitigation systems are available, for example, for the new Ford Galaxy and S-MAX vehicles.

Valeo, Raytheon and M/ACOM, Continental and Hella also use 24 GHz radars for applications such as blind spot monitoring, PSP.

Ru-Cyrl 18-tutorial Sypachev S.S. 1989-04-14 [email protected] Stepan Sypachev students

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Operating principle

Related videos

Police radar classification

Main technical characteristics

Types and ranges of traffic police radars

Radar operating modes

Fundamental radar technologies: - OEM, Ultra-X, Ultra-K (K-Pulse)/(Smartscan™), Instant-On, POP™, HYPER-X™, HYPER-K™.

Radars can combine these technologies to achieve the goals of hiding the signal from the radar detector. For example, "ISKRA 1" simultaneously uses Instant-ON as a switching mode and a combination of PULSE + POP in the form of a pack of 5 short pulses. .

Instant-ON is the mode of turning on the radar, when the radar is initially turned on and in standby mode, but does not emit any signal. After pressing the radar button, it instantly starts emitting a signal and measures the speed of the target it is aimed at. This allows you to remain invisible to radar detectors, which greatly increases the efficiency of the radar, as well as saves battery power of the radar.

POP is a registered trademark owned by MPH Technologies. This technology, unlike Instant-ON, is responsible for the structure of the signal itself. The essence of the technology lies in the fact that the radar, after switching on, emits a very short pulse and with its help measures the speed of the target. The use of this technology complicates the detection of the radar signal by radar detectors, since many models perceive such an impulse as interference and do not issue any warning to the driver. Also, due to the too short pulse, the detection distance is significantly reduced. In order for a radar detector to be able to recognize POP radar signals, it must be equipped with the appropriate protection technology.

PULSE - in addition to POP, there is also a pulse signal technology. It differs from POP in that the pulsed signal is continuously emitted. The duration of the pulses can be different. If it is very short, this can also create a problem for the radar detector, but most modern radar detector models are equipped with pulsed radar protection.

Comparative table of police radars, photographic recorders

Model	TYPE Speedcam	Range	Frequency	Protocol	Speed ​​range	Video range	Calibration interval
Avtodoriya	4	Video	*	GPS/Glonass	10 km	*	2 years
Vocord Traffic	4	Video	*	GPS	Not ogre.	140 m	2 years
Autohurricane RS/VSM/RM	1/3/5	Video	*	*	*	*	1 year
Amata	1	Laser	800-1100 nm	-	700 m	250 m	1 year
Arena	1	K	24.125 GHz	-	1500 m	-	1 year
Barrier-2M	5	X	10.525 GHz	-	-	-	1 year
Golden eagle	5	K	24.125 GHz	K-Pulse	-	-	1 year
Binar	5	K	24.125 GHz	K-Pulse	-	-	2 years
Vizir	5	K	24.125 GHz	-	400 m	-	1 year
Iskra-1	5	K	24.125 GHz	Instant ON/PULSE/POP	400 m	-	1 year
Chris-S/P	1/5	K	24.125 GHz	-	150 m	50 m	2 years
LISD-2F	1	Laser	800-1100 nm	-	1000 m	250 m	1 year
PKS-4	1	K	24.125 GHz	-	1000 m	-	1 year
Radis	1	K	24.125 GHz	-	800 m	-	2 years
Rapier-1	1	K	24.125 GHz	-	-	20 m	2 years
Jenoptik Robot	1	K	24.125 GHz	-	-	-	-
Sokol-M	5	X	10.525 GHz	K-Pulse	-	-	1 year
Arrow ST/STM	1/5	K	24.125 GHz	K-Pulse	500 m	50 m	1 year

TYPE Speedcam determines the type of radar in Navitel navigation charts. .

"APK "AvtoUragan" can be equipped with radar speed meters "Rapira" or "Iskra-1" when it is stationary and radar "Berkut" in the cabin of a patrol car. .

"The Avtodoria registrar only works in video recorder mode.

"VOCORD Traffic can be equipped with speed meters "Iskra-1"DA/130(Chris), "Iskra"DA/210, "Iskra-1"DA/60

Also, the performance of Vocord Traffic is provided in the form of radarless systems in two versions:

1 - as single blocks, where the speed measurement is based on a precise measurement of the time of each frame;

2 - in the form of several cameras for monitoring the average speed on straight sections of roads.

Both Avtodoria, Avtohuragan and Vocord Traffic systems can measure the excess of the average speed on a road section.

Radar simulators

On the roads, they began to install a Lira-1 radar simulator operating in the X band.

Radar simulators work as false video recorders. The principle of operation is to create a radio signal similar to that emitted by road speed meters, while these devices do not have measuring devices.

SWS warning system

The SWS (Safety warning system) warning system is a messaging system for warning of approaching an emergency or accident site. The system is intended for reception with the help of radar detectors (radar detectors). The signal is transmitted at a frequency of 24.060 ... 24.140 GHz. SWS is not used in the CIS.

Dummy video recorders

Models can be converted into active video recorders by inserting the appropriate radar unit and connecting the camera.

Antiradar

For many drivers, fast driving is a common occurrence. Even special electronic equipment has appeared that helps the driver avoid fines. The first

Radar(from English. RA dio D etection A nd R anging (RADAR) - radio detection and ranging , (synonyms: radar, radar station, radar) - a device used to detect and monitor various objects using radio waves and determine the range, speed, direction of movement and geometric parameters of the detected objects.

Invention history

Anti-aircraft radio detector B-2 "Storm", USSR 1935.

The reflection effect of radio waves was discovered in 1886 by the German physicist Heinrich Hertz. Heinrich Rudolf Hertz). In 1897, while working with his radio transmitter, Alexander Popov discovered that radio waves were reflected from the metal parts of ships.
Patents for the invention of radio detection devices were issued in 1905 in Germany, in 1922 in the USA, in 1934 in Great Britain.
In 1934, an experiment was successfully carried out in the USSR to detect an aircraft using the effect of reflection of radio waves - an aircraft flying at an altitude of 150 meters was detected at a distance of 600 meters from the installation. In the same year, prototypes of the Vega and Konus radars for the Elektrovisor aircraft radio detection system were produced at the Leningrad Radio Plant. In the USSR at that time the term "radar" was not used, the first radar stations were called radio traps or radio detectors. Radars were put into service in the USSR in 1939.
The greatest successes in radar before the start of World War II were achieved by the British, who began to massively install radars on warships, and in 1937 created a radar detection network Chain Home along the English Channel and the east coast of England, consisting of 20 stations capable of detecting an aircraft at a distance of up to 350 km.

Operating principle

The principle of radar

Radar is based on the ability of radio waves to be reflected from various objects. In classic pulse radar, the transmitter generates a radio frequency pulse that is emitted by a directional antenna. If an object is encountered along the propagation path of a radio frequency wave, part of the energy is reflected from this object, including in the direction of the antenna. The reflected radio signal is received by the antenna and converted by the receiver for further processing.
Since radio waves propagate at a constant speed, it is possible to determine the distance to the object by the time the signal travels from the station to the object and back: D km \u003d (300,000 km / s * t s) / 2.
In addition to the slant range to the target, radar can also determine the speed and direction of movement, as well as estimate its size.
For radar, VHF and microwave bands are used; the first radar stations, as a rule, operated at frequencies from 100 to 1000 MHz.

Classification

Radars are classified according to many principles, below are the most common parameters for their classification.
On the signal path:

• active (with active response)
• passive

By waveband:

• meter
• decimeter
• centimeter
• millimeter

According to the separation of the receiving and transmitting parts:

• combined
• separate

By location:

• ground
• aviation
• shipborne

By the type of probing signal:

• continuous action
• impulse

By appointment: By appointment:

• early detection and warning
• review
• target designation
• counter-battery combat

By measured coordinates:

• one-coordinate
• two-coordinate
• three-coordinate

By way of scanning space:

• without scanning
• with scanning in the horizontal plane
• horizontal scanning with V-beam
• with vertical scanning
• with helical scanning
• with beam switching

By way of displaying information

• with range indicator
• with separate range and azimuth (altitude) indicators
• with round view indicator
• with azimuth-range indicator

Chronology

• 1886 Heinrich Hertz discovers the effect of reflection of radio waves.
• 1897 Alexander Popov fixes the influence of a passing ship on the operation of a radio communication channel.
• 1904 Christian Hülsmeyer creates a telemobiloscope - a device that captures the reflection of radio waves.
• 1906 Lee de Forest creates the first radio tube.
• 1921 Albert Hull develops a magnetron - a device for generating microwave radio waves.
• 1930 Lawrence E. Highland detects distortion in the passage of radio waves when an aircraft flies between antennas.
• 1931 The US Navy Aviation Radio Laboratory is starting to design a device for detecting enemy ships and aircraft using radio.
• 1934 An experimental American radar detects an aircraft at a distance of 1 mile.
• 1934 In Leningrad, successful experiments were carried out on the radio detection of aircraft.
• 1935 The German company GEMA creates the first radio detection device for the Kriegsmarine.
• 1935 During the experiment at the British military base Orford Ness, it was possible to detect an aircraft at a distance of 17 km.
• 1936 In the UK, the first Chain Home early warning radars were built in.
• 1936 The UK has successfully tested the Type 79X radar installed on the minesweeper HMS Saltburn.
• 1937 The Kriegsmarine adopts Seetakt and Flakleit type radars.
• 1939 An experimental XAF device was built in the United States, for the first time the word radar was used for its name.
• 1939 In Germany, an early warning system based on Freya and Würzburg radars is being put into operation.
• 1939 In the USSR, the aircraft detection station RUS-1 "Rhubarb" was adopted.
• 1939 In the UK, the ASV Mk.I radar was successfully tested on an Avro Anson K6260 aircraft.
• 1940 In the United States, the first SCR-270 early warning radars enter service.
• 1940 The first CXAM radars enter service with the US Navy.
• 1941 GEMA starts installing Seetakt radars on German submarines.
• 1941 The Luftwaffe adopts the first aviation radars FuG 25a "Erstling" and FuG 200 "Hohentwiel".
• 1941 Radar "Redut-K" installed on the cruiser "Molotov".
• 1941 Japan introduced the first Type 11 early warning radar.
• 1942 Radar "Gneiss-2" entered service with Pe-2 aircraft.
• 1942 The US Navy is entering the SCR-584 automatic anti-aircraft gun guidance system.
• 1943 The German Jagdschloss radar is equipped with a POV indicator for the first time.

The general principle of the radar is to emit a pulse of energy (an electromagnetic wave), wait for the arrival of the reflected signal and process it, extracting the necessary information.
The reflected signal can give us information about the location of the object i.e. its azimuth, altitude, range, as well as its speed and direction of movement.
The tasks of the traffic police radar are much narrower - the object is in direct line of sight, the direction of movement is known. It remains only to calculate its speed.

At the same time, the methods of working with it determine some features:
The radar should be light and compact so that the operator can use it while holding it in his hand.
The radar must have built-in power supplies, consume energy economically.
The radar must be safe to use, i.e. the radiated power must be as low as possible.

It is known from radiophysics that the physical dimensions of transmitting and receiving antennas are commensurate with wavelengths. This means that the radar must operate at very short waves (high frequencies), so that its antenna device, together with the transmitter, receiver, decisive and display device, fits in the hand.
In addition, shorter wavelengths improve measurement accuracy. Indeed, at a frequency of 100 kHz, the wavelength will be 3 km. It's like trying to determine the thickness of a hair with a meter rod.
Another limitation is imposed by the small distances over which you have to work.
Most radars used in aviation in the Navy calculate the distance to the target by recalculating it from the time delay of the reflected signal from the emitted one. Then several distance measurements can be converted into speed.
The transmitters of such radars send a short and powerful pulse (duration 1 microsecond, power 600-1000 kW), at a propagation speed of 300,000 km / s, it will reach the target at a distance of 27 km in 90 microseconds, and it will take the same amount to return back. Total - 180 microseconds correspond to 27 kilometers.

The DPS radar does not need such wild powers, but it is short distances that make it impossible to build a radar according to the above scheme.
After all, if the impulse is even only 1 μS, this means that its length in space is 300 meters! That is, the first crests of an electromagnetic wave will reach the target at a distance of 140 meters, they will reflect it, return to the antenna, and then there are the last (and very powerful!) crests of the same impulse. Such a small distance cannot be measured by this method. Moreover, the receiving circuits of such radars are turned off for a short time immediately after the emission of the transmitting pulse, so as not to burn themselves out! It is very problematic to generate radio range pulses shorter than 1 microsecond, so how then to measure short distances and speeds at a short distance?

The physics of the process underlying the construction of the radar was described by the Austrian scientist Christian Doppler back in 1842.
Devices that use the Doppler Effect in their work, allow you to measure the speed of objects at a distance from a few meters to hundreds and thousands of light years.
Traffic police radars operate at frequencies:
10.500 - 10.550 GHz (X-band),
24.050 - 24.250 GHz (K-band),
33.400 - 36.000 GHz (Ka - wide band)
which corresponds to wavelengths of 28, 12 and 9 centimeters, respectively.
At such high frequencies, the resonant circuits are no longer coils and capacitors, as in broadcast receivers, but segments of waveguides (round or rectangular tubes).
The first condition - small size - is already easily met. Even at the lowest frequency, a quarter-wavelength is only 7 cm, and a quarter-wavelength waveguide shorted (baffled) at one end is the equivalent of a tuned parallel oscillatory circuit.
Like any other radar, a traffic police radar consists of a receiver and a transmitter.
The most commonly used transmitter is a Gunn diode oscillator.
Thus, two more conditions are met - a small (minimum sufficient) radiation power and low power consumption.
The receiving part consists of a mixer, an amplifier, a processing unit (computer) and a display device.
Please note that there are no “superheterodynes” in the radar itself, the received reflected signal is immediately mixed with the reference signal, the difference frequency is selected (which is the function of speed, the “Doppler frequency”), then it is amplified and processed. The measured speed is output to the output device.
Traffic police radar transmitters can emit long bursts, short pulses, short pulses in a certain sequence, but since they all emit, it means that everyone can be intercepted (direction finding), you only need the appropriate device - a radar detector.
On the other hand, methods of working with radar can nullify all the tricks of radar detector manufacturers and undisciplined drivers. Indeed, if the “silent” for the time being PR suddenly “shoots” directly at the offender, the signal heard from the warning device will no longer save you from a fine.
In addition to wearable, there are stationary radars. Their signals are confidently detected by all radar detectors, but this is not always required. If in Russia, where the use of radar detectors is allowed, the location of stationary radars is encrypted in every possible way (not officially announced), then, for example, in Lithuania (where the use of radar detectors is prohibited), all stationary posts are indicated on the website of the traffic police, their coordinates are constantly updated in navigator maps , and on the roads in front of them (200-300 meters) there are special warning signs.
Sometimes radar imitators are permanently placed along the roads to intimidate the hurried. These are the simplest devices, radar range signal generators. The simplest because they do not have a complex system for determining speed, their task is to make the radar detector work and cool the ardor of the “racer” at least for a short time. Three or four such noisemakers in a row will dull your vigilance, and the fifth may turn out to be real.
In addition to radars operating in the radio wave bands, laser speed meters are now increasingly used, the so-called. LIDARs (from English - LIght Distance And Ranging).
These devices emit a focused infrared beam (oh, that's the buzzword "nano", the wavelength is nanometers, the pulse duration is nanoseconds) in short pulses and measure the distance, like "large" radars, by the time difference between the transmitted and received pulse. Several distance measurements in a row make it possible to calculate the speed.
The operation of LIDAR is even easier to find than PR of the radio wave range, detection receivers are no more complicated than those that are in all TVs for receiving remote control signals and are now built into almost all radar detectors.
But there is no point in defining the work of a police LIDAR. If your device has signaled, then your speed has already been measured, or you just drove past the automatic doors of a supermarket or gas station.

In some countries, on roads with heavy traffic, speeding violators are even easier to fight - modern technology allows you to fix all cars when entering and leaving the highway. "Champions" who skipped the measured area faster than the allotted time receive a notification by mail about the need to pay a fine.

The most common radar models of the Russian traffic police

RADIS, manufactured by Simikon, St. Petersburg.

Range of measured speeds 10 - 300 km/h
Speed ​​measurement time< 0.3 сек

Iskra-1, manufactured by Simicon, St. Petersburg.
Operating frequency 24.15 + 0.1 GHz (K-band)
Measurement range, not less than 300, 500, 800 m (three levels)
Range of measured speeds 30 - 210 km/h
Speed ​​measurement time 0.3 - 1.0 sec