RU2808952C1 - Target radar method - Google Patents

Abstract

FIELD: radar engineering.

SUBSTANCE: methods for radar detection of targets in a wide area of space, used in surveillance radars. The method of radar targeting for use in surveillance radars, based on measuring the angles of reception of signals reflected from targets, differs in that all targets are irradiated with sounding signals simultaneously using an omnidirectional common-mode antenna, the signals reflected from all targets are received simultaneously to two omnidirectional antennas: to an in-phase and anisotropic in-phase antennas, located at one point in space; in the process of receiving signals from targets, the phase shift is determined between the signals received by the in-phase and anisotropic in-phase antennas, the value of which corresponds to the angle of reception of the signals reflected from the targets, selection of signals from different targets is carried out by the time delay of the signals received from the targets relative to the moment of emission of the probing signal.

EFFECT: reducing the time of establishing a target's flight path to a few milliseconds due to the abandonment of space scanning and omnidirectional irradiation of targets in space with a probing signal and omnidirectional reception of the signal reflected from targets.

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Description

Field of technology to which the invention relates

The invention relates to the field of radar technology, namely to methods for radar detection of targets in a wide area of space and can find application in surveillance radars.

State of the art

There are known methods of target radar intended for use in surveillance radars:

1. Handbook of radio-electronic systems. In 2 volumes. Ed. B.H. Krivitsky. - M.: Energy, 1979.

2. D. Barton, G. Ward. Handbook of Radar Measurements. Per. from English, ed. MM. Weisbein. - M.: Soviet radio, 1976.

3. D. Barton. Radar systems. Per. from English, ed. K.N. Trofimova. - M.: Military Publishing House. 1967.

In relation to methods of surveillance radar of targets, an important technical indicator is the period of observation of a given area of space, which determines the main parameter of the operation of target designation means for air defense fire weapons - the working time of target designation means (Handbook of an air defense officer. Edited by Prof. G.V. Zimin. - M.: Voenizdat, 1978).

D. Barton in (D. Barton. Radar systems. Translated from English, edited by K.N. Trofimov. - M.: Military Publishing House. 1967, Fig. 6.1) considers 7 ways to view the space of a surveillance radar (radar), all from which determine the theoretical value of the review period by the ratio:

T _obz = T _region ⋅F _az ⋅F _mind /θ _az ⋅θ _mind

where: T _region is the time of target irradiation, which is the sum of the radiation time, the time of propagation of the radio signal to the target and back, and the time of accumulation of the signal from the target, necessary to achieve a given threshold for its detection;

Ph _az and _Fum - the required sectors of viewing space in azimuth and elevation;

θ _az and θ _um - the beam width of the radar antenna in azimuth and elevation.

For different methods of viewing space, the implemented viewing times are different. For long- and medium-range radars, viewing times are 6...20 sec. (for example: radar 36D6 - http://www.cons-systems.ru; radar "Casta-2E2" - http://www.roe.ru; radar 64N6E - http://www.milparade.com).

For short-range radars, the space survey time is 2...4 seconds. (for example, radar 76N6E - http://www.RusArmy.com; radar 96L6E - “Nevsky Bastion”, 96L6E; radar 1RL123E - “Equipment and weapons” No. 6 and 7, 2003)

The time for establishing the target's flight path (determining the target's movement parameters), which allows one to draw a conclusion about the presence (or absence) of a target and calculate the parameters of its movement, is determined by the adopted secondary processing algorithm, usually determined by the decision rule “2 out of 3” or “3 out of 4” -x", etc.

Depending on the implemented review time ( _Tobz ), the time of establishing a route and transmitting information about targets to fire weapons for firing them is proportional to the period of review of the space and amounts to:

- to ensure the firing of long-range air defense systems - up to 30...40 seconds;

- to ensure the firing of short-range air defense systems - up to 6...16 sec.

A common disadvantage of the above analogues of the invention is the significant operating time of target designation means, determined by the time interval for establishing the target's flight path (secondary processing of information about the target) and forming parameters of its movement for target designation of fire weapons. In modern conditions, such time delays in the secondary processing of information about the target often lead to the impossibility of timely firing at targets and thus breaking through the defense system.

There are known methods and devices for radio direction finding of radiation sources intended for use in radio reconnaissance systems:

1. Radio direction finder RPs3000i - http://irga.sut.ru/ Radio direction finder RPs3000i.html;

2. Radio direction finder R-359. Technical description. II1.241.017 TO - http://museum.radioscanner.ru/r_359.html.

3. S.V. Kozlov. Direction-finding antenna systems with spatial interference compensation. Educational and methodological manual for specialty 1-39 80 01 “Radio systems and radio technologies”, - Minsk, BSUIR, 2019.

4. Rembovsky A.M., Ashikhmin A.V., Kozmin V.A. Radio monitoring: tasks, methods, means - M: Hotline-Telecom. 2006.

5. Handbook of radio monitoring. ITU 2002. Geneva, 2004.

6. Vartanesyan V.A. Electronic intelligence. - M.: Voenizdat, 1975.

7. Vasin A.A. Short-wave direction-finding antenna arrays with a high-precision direction-finding method. Dissertation for the degree of candidate of technical sciences. - M., MAI, 2012

8. Aliev D.S., Ivanov A.V. Analysis of the designs of modern direction-finding antennas. “Aerospace forces. Theory and Practice" No. 1, March 2017

9. RF patent No. RU 85 676 U1. Published: 08/10/2009, Bulletin. No. 22.

The general disadvantages of the above analogues of the invention are the possibility of detecting only a radio-emitting target, the significant time it takes to search for targets using an emission frequency unknown in advance, the inability to determine the complete vector of target coordinates from one position, and the need for simultaneous direction finding of a target from at least two positions.

As close analogues of the invention, the domestic radar of the Volga-A type (Pegmatite) P-10 (Lobanov M.M. Development of Soviet radar technology. - M. Voenizdat, 1982) and the German radar "Liechtenstein-3" can be considered. (LiSN-3) (Reports of the Special Commission on Radar. Issue 6. Council on Radar under the Council of Ministers of the USSR. - M. Voenizdat. 1946).

Both radars were built on the basis of a system of 4 antennas of the “wave channel” type (2 horizontally and 2 vertically). The range to the target was measured by the delay time of the response signal from the target, and the exact bearing to the target was determined by the phase method using a special goniometer - an auditory meter of the phase difference of the response signal from the target received by various antennas.

Disadvantages of similar analogues of the invention are also the limited dimensions of the antenna radiation pattern width (for the domestic P-10 type radar - 24°). Detection of targets within the radar radiation pattern was ensured without significant delays. However, detection of targets all around was ensured by the classical method of sequential viewing of space by rotating the antenna at a rate of 6 rpm. (1 revolution per 10 seconds).

As a prototype of the invention, RF patent No. RU 2691129 C1, G01S 13/52 “All-round radar station”, publ. 06/11/2019, Bulletin. No. 17.

The achievement of the technical result stated in the RF patent No. RU 2691129 C1 is ensured by the fact that the design of the all-round radar stated in the patent contains a transmitting antenna-feeder device (PRD AFU) and a receiving antenna-feeder device (RPM AFU) of the meter range of electromagnetic waves, spaced apart in space, performed with independent electronic scanning of the airspace for transmission and reception.

The AFU PRD contains flat reflectors installed vertically around the axis of a stationary non-rotating transmitting mast, between adjacent planes of which two-tier loop vibrators of horizontal polarization with central power supply through a distribution feeder are installed.

The AFU PRM contains four identical tiers of three half-wave vibrators of horizontal polarization crossed with each other in the horizontal plane, placed on a stationary vertical non-rotating mast.

This implementation of the AFU PRD and AFU PRM allows, according to the authors of the prototype invention, to apply the method of phase measurement of the azimuth of air objects without the use of four bulky azimuth receiving antennas.

The supporting masts of the AFU PRD and AFU PRM are spaced on the ground at a distance d to protect its receiving paths from suppression by probing radiation.

The radar uses two types of sounding signals:

- short τ ₁ with amplitude modulation (AM) or linear frequency modulation (chirp) and

- long τ ₂ with chirp at different frequencies f ₁ and f ₂ , which are emitted sequentially in time.

The disadvantages of the prototype of the invention are:

- use of the meter wave range prohibited for use for the radiolocation service by the Radio Regulations, ITU, Geneva, 2016;

- significant (more than 50 m) separation in space of transmitting and receiving antenna-feeder devices, excluding the possibility of creating mobile (self-propelled) radars;

- quadrant survey of space (in accordance with the accepted method of disambiguating the phase measurement of the azimuth of air targets and the design of the transmitting antenna-feeder device);

- large size of the “dead” zone of the near boundary of the target detection zone, caused by the need to sequentially emit two signals at two different frequencies.

Disclosure of the invention

The essence of the proposed method for target radar is based on omnidirectional azimuth radiation of the probing signal simultaneously to all targets and omnidirectional azimuth reception of the signal reflected from all targets.

Common-mode radiation of the probing signal is carried out by an isotropic (for example, a loop antenna or a vertical system of loop antennas to increase the directivity of the antenna).

Reception of the reflected signal from targets is carried out by two antennas (antenna systems):

- reference in-phase (isotropic in phase) signal - to an isotropic antenna (for example, to a loop antenna or a system of loop antennas), including one used for emitting a probing signal;

- phasometric (anisotropic in phase) signal - to an anisotropic antenna that forms an electromagnetic field rotating with the frequency of the signal (for example, a turnstile antenna or a turnstile antenna system).

Summing the reference signal from the isotropic (loop) antenna and the phaseometric signal from the anisotropic (turnstile) antenna on the phase discriminator and thus determining the difference in the phases of the signals received by the isotropic and anisotropic antennas makes it possible to determine the angular position of each signal reflected from the targets.

To reduce the near boundary of the target detection zone in range, a short-duration monochromatic signal is used.

The technical result of the proposed radar method is achieved in the simultaneous receipt of a full amount of information about targets from all angles of the possible location of targets in azimuth and elevation. In this case, the parameter that determines the condition of the decisive rule of secondary processing is the repetition period of the probing pulses, which usually lies within a few milliseconds.

Thus, the time interval between receiving the first reflected signal from the target and receiving the full vector of target motion parameters is reduced by more than 1000 times relative to the classical method of locating surveillance type targets and 4 times compared to the location method according to RF patent No. RU 2691129 C1.

Brief description of the drawings (if they are included in the application)

The appearance of a variant of the antenna design on a support structure that implements the claimed location method is shown in Fig. 1, where the numbers indicate: 1 - supporting structure; 2 - turnstile antenna made of half-wave vibrators (directors); 3 - loop antennas.

The connection diagram for the transmitting/receiving antenna of the reference signal is shown in Fig. 2, where the numbers indicate: 3 - frame transceiver antennas; 4 - balun transformers; 5 - RF adders; 6 - RF splitters; 7 - phase shifters; 8 - circulators; 9 - transmitter; 10 - reference channel receiver.

The RF signal of the transmitter 9, through circulators 8, which ensure decoupling of the transmitting and receiving channels, is supplied to phase shifters 7, which ensure the deviation of the main maximum of the antenna radiation pattern from frame antennas 3. The transmitter signal, after a phase shift by phase shifters 7, is supplied to HF splitters 6 and then to HF adders 5. The signal from the adders 5 goes to the balun transformers 4 and then to the loop antennas 3, which form the radar sounding signal in space. A complex system of RF combiners and splitters is necessary to link the phase center of loop antennas 3 to the phase center of director antennas 11 of the phase-metric channel.

The connection diagram for the receiving antenna of the phase-metric channel is shown in Fig. 3, where the numbers indicate: 4 - balun transformers; 5 - RF adders; 7 - phase shifters; 10 - reference channel receiver; 11 - director turnstile antenna; 12 - phase-shifting chain; 13 - phase channel receiver; 14 - phase discriminator.

The reflected signal from the target is received by the orthogonal vibrators of the director turnstile antenna 11. The phase-shifting chain 12 ensures a rotation of the phase of the signal received by the orthogonal vibrators of the antenna 11 by 90°, which ensures rotation of the polarization basis of the electromagnetic field of the receiving antenna 11 with the frequency of the signal. Signals from the vertical system of director antennas 11 through phase shifters 7, which ensure the deviation of the main maximum of the directional pattern of the director turnstile antenna synchronously with the deviation of the main maximum of the directional pattern of the transmitting loop antenna, arrive at the RF adders 5 and then to the receiver of the phase channel 13. The reflected signal received by the receiver 13 from the targets, together with the reference signal from the reference signal receiver 10, is sent to the phase discriminator 14. The results of measuring the phase shift between the reference and phase-measuring channels are sent for further processing.

An example of a functional diagram of a device that implements the developed radar method as a whole is shown in Fig. 4, where the numbers indicate: 15 - synchronizer; 16 - code of the partial radiation pattern number; 17 - synchronizing pulses of probing signal radiation; 9 - transmitter; 18 - digital phase calculator; 6 - RF splitter; 8 - circulator; 7 - phase shifter; 3 - transmitting and receiving antenna of isotropic radiation; 5 - RF adder; 2 - director turnstile antenna; 10 - reference channel receiver; 13 - phase channel receiver; 11 - phase discriminator; 19 - calculating device for calculating the phase difference and converting it into a system of spatial angular coordinates; 20 - range/elevation channel matrix; 21 - a counting and solving device for identifying marks from targets, tying the flight paths of targets and the parameters of their movement.

Synchronizer 15 provides general synchronization of the device by generating a sequence of synchronization pulses, probing pulses 17 and codes for switching the antenna pattern by elevation angle 16 (if necessary).

The synchronous pulses of the radiation of the probing signals 17 are sent to the transmitter 9, which generates probing radio signals at a given radiation frequency. The sounding radio signals through the RF splitter 6 are supplied to the circulators 8 of all transmitting loop antennas 3 through the phase shifters 7.

Using codes 16 generated by synchronizer 15 and digital phase computer 18, control signals for phase shifters 7 are generated to switch the elevation angle of the radar radiation and receive signals from targets.

Signals from targets are received simultaneously by both loop 3 and turnstile director antennas 2.

The signals received by the loop antennas 3, through the phase shifters 7 and circulators 8, through the RF adder 5, enter the receiver of the reference channel 10.

The signals received by the turnstile director antennas 2, through the phase shifters 7, through the RF adder 5, enter the receiver of the phase channel 13.

The receivers of the reference channel 10 and the phase channel 13 also receive a sequence of probing pulses 17 from the synchronizer 15 to lock the input circuits of the receivers while the transmitter 9 is emitting probing signals.

Signals from targets received by the receivers of the reference 10 and phase 13 channels are supplied to the phase discriminator 11, which determines the difference in the phases of the signals received by the receivers of the reference 10 and phase 13 channels.

The phase difference of the signals received by the receivers of the reference 10 and phase 13 channels is sent from the phase discriminator 11 to the computing device 19, where the analog phase difference is converted into digital form and recalculated into a system of spatial angular coordinates as target azimuth ϕt.

The measured target azimuth ϕt together with the target elevation angle Ets according to code 16 of the digital phase calculator 18 and the range to the target according to the time delay of the received signal from the target relative to the synchronizing pulse of the probing signal 17 is entered into the channel matrix range/azimuth/elevation angle 20.

The counting and decision device for identifying marks from targets, tying flight paths of targets and determining the parameters of their movement 21 carries out secondary processing of the results of primary detection of targets from the matrix 16 according to known criteria: receiving n marks from targets from m request signals, criterion for resetting the route: k omissions of receipt marks from targets) for further transfer of linked flight paths of detected targets to air defense fire weapons.

Carrying out the invention

An example of the invention is shown in Fig. 1…4.

An example of a radar design that implements the claimed target location method is based on a horizontal polarization antenna system that works to receive and transmit sounding signals. The choice of horizontal polarization in relation to the example of the claimed location method is not critical and only reflects the desire to maximize the reflection of radio waves from the target due to the developed aerodynamic surfaces of aircraft, helicopters and cruise missiles or remote engine consoles of small-sized “drones”.

The receiving antenna, which is anisotropic in phase, is a vertical line of half-wave vibrators (directors), connected according to a turnstile circuit and placed on the supporting structure at intervals equal to λ/2.

The transmitting phase isotropic antenna, which simultaneously performs the function of the receiving antenna of the reference signal, is a vertical line of loop antennas placed on the supporting structure at intervals equal to λ/2 with a shift relative to the half-wave vibrators of the receiving antenna at intervals equal to λ/4, where λ - wavelength of the emitted signal.

The target azimuth is determined by the phase shift between the signals received by in-phase (isotropic in phase) omnidirectional in azimuth and anisotropic in phase omnidirectional in azimuth antennas; selection by range of signals from different targets is carried out by the time delay of the received signals relative to the emitted probing signal

The proposed method for target radar is invariant to the choice of wavelength of the emitted signal (frequency range of operation).

To eliminate the main drawback of the prototype of the invention, it is proposed to use frequency ranges of operation in accordance with the distribution of frequencies allocated by the Radio Regulations (ITU, Geneva, 2016) for the radiolocation service, for example: RR5-42, lines 3...5; PP5-54, lines 3…5; PP5-62, lines 4…6; PP5-65, lines 1…2, etc.

Claims (1)

A method of target radar for use in surveillance radars, based on measuring the reception angles of signals reflected from targets, characterized in that all targets are irradiated with sounding signals simultaneously using an omnidirectional in-phase antenna, the signals reflected from all targets are received simultaneously on two omnidirectional antennas: an in-phase and phase-anisotropic antennas located at one point in space; in the process of receiving signals from targets, the phase shift is determined between the signals received by the in-phase and phase-anisotropic antennas, the value of which corresponds to the angle of reception of the signals reflected from the targets; the selection of signals from different targets is carried out by a time delay signals received from targets relative to the time of emission of the probing signal.