WO2003065071A1 - Systeme radar et procede de commande de systeme de radar - Google Patents

Systeme radar et procede de commande de systeme de radar Download PDF

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Publication number
WO2003065071A1
WO2003065071A1 PCT/NO2003/000034 NO0300034W WO03065071A1 WO 2003065071 A1 WO2003065071 A1 WO 2003065071A1 NO 0300034 W NO0300034 W NO 0300034W WO 03065071 A1 WO03065071 A1 WO 03065071A1
Authority
WO
WIPO (PCT)
Prior art keywords
radar system
antenna
signals
designed
radar
Prior art date
Application number
PCT/NO2003/000034
Other languages
English (en)
Inventor
Per-Arne Isaksen
Original Assignee
Per-Arne Isaksen
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from NO20020511A external-priority patent/NO20020511D0/no
Priority claimed from NO20021917A external-priority patent/NO20021917D0/no
Application filed by Per-Arne Isaksen filed Critical Per-Arne Isaksen
Publication of WO2003065071A1 publication Critical patent/WO2003065071A1/fr
Priority to NO20043638A priority Critical patent/NO328309B1/no

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/06—Systems determining position data of a target
    • G01S13/42—Simultaneous measurement of distance and other co-ordinates
    • G01S13/426—Scanning radar, e.g. 3D radar
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/87—Combinations of radar systems, e.g. primary radar and secondary radar
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q21/00—Antenna arrays or systems
    • H01Q21/24—Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q25/00—Antennas or antenna systems providing at least two radiating patterns
    • H01Q25/005—Antennas or antenna systems providing at least two radiating patterns providing two patterns of opposite direction; back to back antennas
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
    • H01Q3/02—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical movement of antenna or antenna system as a whole
    • H01Q3/04—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical movement of antenna or antenna system as a whole for varying one co-ordinate of the orientation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/024—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using polarisation effects
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/28—Details of pulse systems
    • G01S7/285—Receivers
    • G01S7/292—Extracting wanted echo-signals
    • G01S7/2923—Extracting wanted echo-signals based on data belonging to a number of consecutive radar periods
    • G01S7/2926—Extracting wanted echo-signals based on data belonging to a number of consecutive radar periods by integration

Definitions

  • An object of the invention is to provide a new solution for a radar system in this category by increasing the ability to detect targets during adverse weather conditions, and also provide a presentation of the radar image shown in relative real time.
  • the present radar systems have many weaknesses and stand almost unchanged since the 1940s. True, information technology, also in radar systems, has changed radically with the entry of the microprocessor and raster scan display. However, these changes have not entailed an equally radical positive change for the detection ability of the radar systems, which after all is the primary function of a radar system.
  • the antenna systems of the conventional navigational radar and the units of the transceiver consist substantially of the same units and are based on the same functionality/technology as at the beginning, in the 1940s.
  • the changes in this part of a navigational radar system is that the parabolic antenna has given way to the far more reasonable “slotted wave guide” antenna and that the "tube” technology has been replaced by transistors and microchips.
  • Pd detection probability
  • the conventional transceiver system consists of an antenna that is horizontally polarised and a transceiver system that transmits and receives radar signals at a fixed frequency.
  • FD Systems Frequency Diversity systems
  • These systems often make use of an antenna, preferably a slotted wave guide antenna or a parabolic antenna with two or more antennae that transmit and receive with two or more different beams.
  • FD radar makes use of a slotted wave guide antenna, a scattering of the antenna beams will result, which is called the "squint effect" and is a function of among other things the difference in frequency between the transmitters.
  • the difference between the beams is typically 1 to 3 degrees.
  • Such FD systems can show a higher Pd in comparison with regular radar systems.
  • the capacity for improved detection in relative real time is limited, especially in regard to improved Pd in sea clutter (background noise from a sea echo).
  • the main reason is that the time delay between the antenna beams across a target is relative to the rpm of the antenna, and this time difference should not be much smaller than 50-60 milliseconds.
  • the present invention also termed the "Sea-Hawk technology" provides a solution in which these factors and components have been solved in order to give a higher Pd for targets in clutter, in particular in sea clutter.
  • the integration time in the Sea-Hawk system is typically 0.25 - 0.5 seconds (integration of HH + VV related to rpm). This is longer than the de-correlation time of Bragg scattering, and will result in an improvement of the signal to clutter ratio, independently of the polarisation diversity. At the same time, the integration time is shorter than the de-correlation time for the slow component, i.e. spikes of sea clutter. The polarisation diversity of the Sea-Hawk will therefore de-correlate the slow component, which results in an improved signal to clutter ratio compared with single polarisation.
  • the slow component of the sea clutter behaves differently in the different polarisations, and this is used to de-correlate the slow component of the sea clutter through the integration time when the two components are combined coherently.
  • the Sea-Hawk concept then combines de-correlation of the fast component of the sea clutter with a multiple polarisation which also de-correlates the slow component of the clutter. The result is an increased probability of detection of targets in sea clutter. (There will be a limited scope for achieving more or less the same effect with equal polarisation (e.g. HH + HH) of the different antenna elements, provided they transmit and receive using mutually different frequencies (FD-radar)).
  • the Sea-Hawk technology is characterised in that among other things, it employs an antenna consisting of two or more independent elements (apertures) that rotate about a common axis. When two apertures are used, these are placed back to back; consequently transmitting and receiving radar signals offset by 180 degrees from each other ("back to back beam”). This means that the number of apertures is divided by 360 degrees, so that the beams of the antenna transmit and receive equidistantly spaced signals - Asymmetric Azimuth Beam Divergence (AABD). When using e.g. three apertures the antenna transmits and receives in three different directions, where the beams are offset by 120 degrees from each other (star).
  • AABD Asymmetric Azimuth Beam Divergence
  • the apertures of the antenna are linearly polarised but with mutually different polarisation.
  • the preferred choice is HH (horizontal), VV (vertical) and CC (circular).
  • the preferred choice is HH + VV.
  • the circular aperture in itself has good properties in precipitation (rainfall), and may be selected as an auxiliary function, in particular to reduce the clutter generated by atmospheric conditions such as precipitation. It will also be possible to operate an integration of HH + VV + CC when using three apertures in the antenna.
  • the antenna has been called a hybrid antenna.
  • FIGS 2, 3a, 3b, 5, 6a and 6b illustrate different principles of a hybrid antenna.
  • the transceiver system The Sea-Hawk system is normally operated on only one frequency. That is, one transmitter, but with independent RF components and receivers for each aperture (see Figure 7).
  • transceiver system that can transmit and receive signals in two or more channels simultaneously and/or in a controlled sequence.
  • the channels are separate through using mutually different frequencies (Frequency Diversity - FD).
  • TRX transceivers
  • the transceivers (TRX) transmit and receive signals at their individual significant frequencies over relative time (e.g. "Pulse to Pulse” or over the centre azimuth beam of the antenna elements).
  • the signals to and from TRX are mixed and separated either through using two diplexers, one before the rotation joint in the antenna drive and one between the antenna elements, so as to allow separation of the signals between significant selection of antenna element/aperture; or by the other method, which is to use a two or more channel rotation joint, thus to achieve a separation (isolation) and selection between the respective TRX and antenna element/aperture.
  • the method of using separate TRXs could be made such that the entire Sea-Hawk system meets the existing requirement for separate radar systems (two separate systems). In this connection, an antenna number two must be introduced.
  • This unit serves to synchronise the received radar signals to allow video to be combined into one unified image.
  • the combining is performed in the Combiner Video Unit (CVU - 9), which in principle delays the signals in one channel (3), so as to allow "summation" of the delayed signal and the other channel (12).
  • the synchronisation of the CVU is controlled by the Heading Marker (HM - 5) and the Azimuth Counter (AC - 7). HM and AC generate the clock signals that make sure the Video Delay (VD) delivers that signal which is coincident with the signals in Video RX B - 12 in terms of direction/ bearing. This timing is important for the Combiner Video (CVU - 9) to be able to add up the channels at the right time.
  • the gyro (Gyro Comp) signals are used to compensate for any changes in angular velocity between the channels caused by the rotation of the vessel about its own axis - the central axis (JAV).
  • This signal is considered an error signal (correction) in JAV and will be an addition signal or deduction signal related to whether the rotation is a movement to the right or to the left with respect to the rotational direction and rpm of the antenna.
  • the Combiner Video and Sync Signal Unit delivers the summed video signal to the display.
  • CVU (9) adds up/ correlates/ integrates/ demodulates and processes the video signals into a unified synchronous signal generated by the various video signals provided by the receivers.
  • the CVU has its own External Trigger Unit (14), which incidentally is required to be able synchronise the entire transceiver system so that the radar signals from the different channels (receivers) occur at the right time.
  • the principle is the same when using three or more channels.
  • the synchronisation between the channels is then carried out in several parts and with a corresponding mutual delay.
  • the video unit of the arrangement is a Combiner Video Unit as shown in Figure 4.
  • correction and adjustment due to JAV in CVU The main features of the arrangement can be summarised and characterised in that when the radar itself is in motion, such as on a vehicle, ship, aircraft or similar, the video signals from the individual receivers are adjusted, making corrections for the rotation of the vehicle/ship/aircraft about its own axis (JAV) in relation to the direction of rotation and rate of rotation (rpm) of the antenna, and the video unit is designed to correct errors at the point of summation due to the JAV effect, by using the gyro of the vehicle/ship/aircraft as a correcting image and delivering it to video-sync, so that the video unit (CVU) and the sync-signal show a corrected and coincident image.
  • JAV rotation of the vehicle/ship/aircraft about its own axis
  • rpm direction of rotation and rate of rotation
  • the antenna can consist of two apertures mounted back to back and polarised HH (horizontally) and VV (vertically) respectively. 2. Turning unit.
  • Transceiver A This has a different frequency from transceiver B. The frequency difference is typically 100 MHZ but may be greater.
  • Transceiver B 7. Video signal from receiver A to Video Combiner Unit.
  • This figure shows a hybrid antenna consisting of two antenna elements (apertures) arranged back to back, where the individual antenna elements transmit and receive signals offset by 180 degrees relative to each other.
  • the antenna elements Preferably, the antenna elements have different polarisation.
  • Figure 3a shows the hybrid antenna with three different elements (channels/apertures) assembled to act as an antenna with a common axis.
  • An assembly as shown in Figure 3 consists of elements that may have e.g. Vertical (VV), Horizontal (HH) and Circular (CC) polarisation.
  • the antenna beams are mutually equidistant, and in this case they will be offset by 120 degrees from each other.
  • Figure 3 b shows an assembly of elements (apertures) where each equally polarised aperture transmits and receives signals offset by 180 degrees. At the same time, each differently polarised element (HH + VV + CC) is offset by 120 degrees (star). As a result, the individual beams are offset by 60 degrees from each other.
  • Video for channel B 13. Combined Video and sync signal
  • the task of this unit is to synchronise the TRXs, so that the video signal from the receivers can be assembled into one unified image.
  • the assembly takes place in the Combiner Video Unit (CVU - 9), which in principle delays the signals in one channel (Video Delay - 3) to allow the delayed signal to be "added” to the other channel (12 - Video for channel B).
  • Synchronization of the CVU is controlled by the Heading Marker (5) and the Azimuth Counter (AC).
  • HM (4) and AC (7) generate the clock signals to ensure that the Delay Video (3) delivers the signal that coincides with the signals in video from receiver B (12) in terms of direction (bearing). This is important for the Combiner Video (9) to be able to process the channels at the right time and consequently one image (13).
  • the gyro signals (8) are used to compensate for any changes in angular velocity between the channels and the receivers caused by rotation of the vessel about its own axis (JAV).
  • This signal occurs as an error signal in JAV and will be an addition signal or deduction signal related to whether the rotation is a movement to the right or to the left with respect to the rotational direction and rpm of the antenna.
  • the Combiner Video and Sync Signal Unit delivers the summed video signal to the display. This unit can also deliver a separate display trigg if required.
  • CVU has its own External Trigger Unit, which incidentally is required to be able to synchronise the entire transceiver system so that the summation of video from the different channels (receivers) occurs at the right time.
  • the principle is the same when using two or three different channels.
  • the synchronisation between the channels is then carried out in several parts and with a corresponding mutual delay.
  • the video unit of the arrangement is a Combiner Video Unit as shown in Figure 4.
  • Figure 5 shows a multifunctional antenna consisting of two antenna apertures (1 and 2) arranged back to back, where the individual antenna elements transmit and receive signals offset by 180 degrees from each other (5 and 6).
  • the antenna elements can be given different polarisation (HH + VV).
  • To each antenna element (aperture) is mounted a separate receiver unit (3 and 4).
  • Figure 6a shows a multifunctional antenna where three different apertures (1, 2 and 3) have been assembled to form an antenna that rotates about a common axis.
  • An assembly as shown in figure 6a consists of apertures with e.g. vertical, horizontal, and circular polarisation.
  • To each aperture is mounted a separate receiver unit (7, 8 and 9).
  • the antenna beams are equidistantly spaced, and in this case they will be offset by 120 degrees from each other (4, 5 and 6).
  • Units 8 and 9 can be mounted in the aperture.
  • unit 3 is a rotation joint and acts as one; the difference being that optical signals are transmitted in the cavities at the same time.
  • the optical transmitter and receiver transmits and receives IF, video, command and control signals through the cavity of the rotation joint.
  • An optical signal is considered a disturbance factor for the "stationary wave ratio" in the wave guide system. The optical signals are only transmitted when the transmitter (6) is not transmitting.

Landscapes

  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

L'invention concerne un système radar permettant principalement d'accroître la probabilité de détection dans des conditions météorologiques difficiles et d'améliorer la détection de cibles présentant des vitesses relatives élevées, et qui produit une présentation de toutes les cibles en temps réel. Ce système radar comprend une antenne hybride incluant au moins deux éléments d'antenne indépendants pouvant transmettre et recevoir des signaux radar dans des directions différentes ; la distance angulaire entre toutes les directions est la même, et chaque élément d'antenne est conçu pour pouvoir transmettre et/ou recevoir des signaux dans au moins une polarisation et/ou une fréquence sélectionnée(s). Ce système radar comporte aussi des moyens pour faire tourner le rayonnement dans le champ de vision. L'invention est notamment applicable dans les domaines de la navigation, de la surveillance et VTS.
PCT/NO2003/000034 2002-02-01 2003-02-03 Systeme radar et procede de commande de systeme de radar WO2003065071A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
NO20043638A NO328309B1 (no) 2002-02-01 2004-08-31 Radar system

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
NO20020511A NO20020511D0 (no) 2002-02-01 2002-02-01 Radarsystem
NO20020511 2002-02-01
NO20021917A NO20021917D0 (no) 2002-03-04 2002-03-04 Radarsystem
NO20021917 2002-03-04

Publications (1)

Publication Number Publication Date
WO2003065071A1 true WO2003065071A1 (fr) 2003-08-07

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/NO2003/000034 WO2003065071A1 (fr) 2002-02-01 2003-02-03 Systeme radar et procede de commande de systeme de radar

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017200948A1 (fr) * 2016-05-19 2017-11-23 Board Of Regents Of The Nevada System Of Higher Education, On Behalf Of The University Of Nevada, Reno Découverte et maintenance de liaison directionnelle entre mobiles

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3648284A (en) * 1969-08-06 1972-03-07 Westinghouse Electric Corp Two-face phased array
US4041489A (en) * 1974-06-25 1977-08-09 The United States Of America As Represented By The Secretary Of The Navy Sea clutter reduction technique
US20010019314A1 (en) * 1999-12-10 2001-09-06 Thomson - Csf Method of exploration in azimuth for a radar, and radar implementing the method

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3648284A (en) * 1969-08-06 1972-03-07 Westinghouse Electric Corp Two-face phased array
US4041489A (en) * 1974-06-25 1977-08-09 The United States Of America As Represented By The Secretary Of The Navy Sea clutter reduction technique
US20010019314A1 (en) * 1999-12-10 2001-09-06 Thomson - Csf Method of exploration in azimuth for a radar, and radar implementing the method

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017200948A1 (fr) * 2016-05-19 2017-11-23 Board Of Regents Of The Nevada System Of Higher Education, On Behalf Of The University Of Nevada, Reno Découverte et maintenance de liaison directionnelle entre mobiles

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