WO1986007467A1 - Radar de surveillance a faisceaux multiples - Google Patents
Radar de surveillance a faisceaux multiples Download PDFInfo
- Publication number
- WO1986007467A1 WO1986007467A1 PCT/GB1986/000347 GB8600347W WO8607467A1 WO 1986007467 A1 WO1986007467 A1 WO 1986007467A1 GB 8600347 W GB8600347 W GB 8600347W WO 8607467 A1 WO8607467 A1 WO 8607467A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- sub
- pulses
- radar system
- pulse
- azimuth
- Prior art date
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
Definitions
- the present invention relates to improvements in or relating to radar systems.
- a conventional surveillance radar system transmits a sequence of pulses of radiation each of which is directed towards a particular azimuth direction depending upon the instantaneous position of a mechanically rotating directional antenna. After each of these transmission pulses has been transmitted the radar seeks to receive the pulse radiation reflected from targets which may be at any distance up to a designed maximum range from the radar. The time required for this reception period depends upon the maximum range and is approximately 1 ms for each 150 km.
- the pulse repetition interval places an upper limit on the rate at which pulses may be transmitted, and, due to the narrow rotating beam, it limits the number of pulses which may be transmitted towards a given potential target in each antenna rotation period.
- the pulse repetition rate also places a limit on the maximum angular rate at which the antenna may be turned whilst transmitting at least one pulse towards each potential target on every rotation.
- the present invention seeks to provide a radar system having azimuth diversity whereby an increase in the number of pulses directed towards a potential target in each antenna rotation from more than one azimuth direction within the same pulse repetition interval may be achieved.
- a radar system comprising a transmitter for generating transmission pulses for enabling the generation of radiated beams by an antenna, a signal pulse comprising a number of sub pulses, at least one sub pulse being arranged at a centre frequency which differs from the centre frequency of at least one other .sub pulse for enabling more than one azimuth direction to be illuminated by the radiated beams.
- each sub pulse is arranged at a centre frequency which differs from the centre frequency of every other sub pulse for enabling a number of azimuth directions corresponding to the number of sub pulse to be illuminated by the radiated beams.
- each transmission pulse comprises two sub pulses.
- the transmitter may be arranged to generate two transmission pulses per azimuth beamwidth of the system, each transmission pulse comprises two sub pulses, whereby two groups of two sub pulses are transmitted per azimuth beamwidth and wherein the centre frequencies of the sub pulses are arranged such that the radiated beams are evenly spaced by approximately one quarter of the system azimuth beamwidth.
- Figure 1 illustrates a general schematic diagram of an azimuth diversity radar system in accordance with the present invention.
- Figure 2 illustrates a schematic diagram showing how transmitted pulse groups may be arranged in the system illustrated in Figure 1 to provide separated transmitted beams within the azimuth beamwidth of the radar system.
- a radar system 2 comprises a transmitter 4 coupled to one or more rotatable antennas 6, only one of which is shown for clarity.
- the antenna 6 is used for the transmission of a radiated beam and exhibits the property that the azimuthal direction of the beam of radiation formed by the antenna is dependent upon the frequency of the excitation pulses afforded by the transmitter 4.
- a frequency selector 8 is coupled to the transmitter 4 for enabling the frequency of the output of the transmitter to be selected according to requirements.
- a receiver 10 is provided, coupled to the antenna 6.
- the receiver 10 comprises receive and detection circuits 12, 14 and azimuth determination circuits 16, 18; which are also coupled to the frequency selector 8.
- the antenna 6 may be used for transmission and reception, the azimuthal directions of the transmit and receive beams being coincident for any frequency and also dependent on that frequency.
- An example of such an antenna is one consisting of one or more substantially horizontally mounted slotted linear waveguides, fed from one end. In such antennas the transmission path delay within the waveguide imparts the necessary frequency sensitivity to the beam position in azimuth.
- the receiver 10 is coupled to a plot extractor 20, the function of which will be described later.
- the transmitter 4, in conjunction with the frequency selector 8 is arranged to be capable of transmitting more than one pulse on different frequencies in rapid succession.
- the transmitter 4 may be easily implemented using a driven amplifier such as a travelling wave tube, a klyston, a cross-field amplifier or a solid state amplifier. - 5 -
- a driven amplifier such as a travelling wave tube, a klyston, a cross-field amplifier or a solid state amplifier.
- magnetrons or a very rapid turning magnetron, or any other suitable means, may be employed.
- sub-pulse is used to describe a pulse transmitted with a particular centre frequency. Where necessary for signal processing purposes, sub-pulses may carry within pulse modulation.
- pulse group describes several sub-pulses which, when transmitted, are separated in time by only a small fraction of a pulse repetition interval. Each sub-pulse within a pulse group is transmitted with a different centre frequency. Pulse groups are separated in time by one pulse repetition interval.
- the transmitter 4 generates the transmission pulses of a conventional radar system in the form of groups of sub-pulses, such as the sub-pulses f ⁇ and ⁇ 2 shown in Figure 1.
- the frequencies f ⁇ and f2 are chosen so that the individual radiated beams 22, 24 are conveniently separated in azimuth.
- Each sub pulse i_ , f 2 excites the antenna 6 to generate one beam.
- the sub pulses cause the radar system 2 to illuminate a number of azimuth directions corresponding to the number of sub pulses having individual centre frequencies; two in the system shown in Figure 1.
- the azimuth spacing between the contemporaneously illuminating beams 22, 24 may be greater than or less than one azimuth beamwidth and will depend upon the frequency spacing between the sub-pulses.
- the frequency spacing may be set in the frequency selector 8 to be appropriate to the operational requirement of the radar system 2. For example, a typical slotted waveguide linear array operating near to 3 GHz requires a frequency change of approximatly 50 MHz to move the directional beam radiated by the aerial through one beamwidth in azimuth.
- echo signals may be received from targets located in any of the illuminating beams 22, 24.
- the signals are received by the receiving antenna (which may be identical with the transmitting antenna) because their azimuth of arrival and their frequencies correspond.
- the signals then pass through the receiver 10 and signal processing system where the identities of signals resulting from the individual sub-pulses are preserved.
- the receiver 10 is capable of simultaneously receiving sub-pulses on different frequencies and processing these so that the results of detection may be separately ascribed to the different frequencies f ⁇ and f 2 . and hence to different azimuths. In the embodiment of Figure 1 this is achieved by the receive and detection circuits 12, 14 and the azimuth determination circuits 16, 18. More than one receiver and signal processing system may be required to preserve the identity of the signals, however other means such as coding the signals may also be possible.
- an azimuth can be ascribed to each target echo. When more than one echo is detected from any target they can be combined in a plot extractor 20 to provide a plot output and hence a better estimate of target position.
- Figure 2 illustrates how a two beam azimuth diversity system may be used to double the number of target illuminations per beamwidth and to spread these evenly in azimuth.
- the pulse group contains two sub-pulses of frequencies fl and f2.
- the pulse repetition interval is shown as one half azimuth beamwidth and so two pulse groups are transmitted per beamwidth.
- the separation between the frequencies fl and f2 is chosen so that the resulting two azimuth beams are separated by one quarter azimuth beamwidth and thus four evenly spaced sub-pulse beams are radiated in every beamwidth.
- the frequencies of the sub-pulses f ⁇ and f 2 appear alternately and so the detection advantages of frequency diversity may be claimed.
- the sub-pulse beams are separated by one quarter of the azimuth beamwidth.
- the same effect may be achieved with separation of any odd multiple of one quarter beamwidth.
- the optimum separation depends upon the number of pulse groups per beamwidth and may also be influenced by other requirements such as stagger within multi target indicator pulse bursts.
- the maximum antenna rotation rate which may be used whilst illuminating each potential target direction with at least one pulse within each antenna rotation may be increased.
- an azimuth diversity radar transmits pulses on more than one frequency during each pulse repetition interval, then the separation of the azimuth directions towards which the pulses are transmitted can be chosen so that, where more than one pulse illuminates a potential target within each antenna rotation period, the illumination of the target will be by pulses of more than one frequency. It will be appreciated, therefore, that the detection sensitivity and advantages normally ascribed to "Frequency Diversity" can be realised.
- the radar ' system is not restricted to any particular number of sub-pulses within each pulse group, neither is it limited to any particular azimuthal separation between the beams so generated.
- the frequencies of the sub-pulses In the case of radars operating with frequency agility it is permissible for the frequencies of the sub-pulses to have no fixed relationship to each other and to be chosen from all available frequencies within the radar bandwidth using whatever selection algorithm or mechanism as would normally be used in a conventional frequency agile radar.
- Such an algorithm could be stored in any suitable memory device associated with the frequency selector 8 which would cause the transmitter 4 to generate sub-pulses as determined by the algorithm.
- the azimuth determination circuits 16, 18 would also respond to the algorithm to enable the azimuth associated with any sub-pulse to be determined.
- the principles of the present invention may be applied to either two dimensional radars (i.e. those which do not measure target height) including air and surface search radars, or to three dimensional radars; azimuth diversity being of particular value in three dimensional radars because the number of pulse repetition intervals available per azimuth beamwidth at each elevation in such radars is often limited due to the time required to examine several different elevations.
Abstract
Un système radar comprend un émetteur qui divise chaque impulsion émise en une pluralité de sous-impulsions, en deux impulsions dans le mode préférentiel de réalisation. Les sous-impulsions ont des fréquences différentes (f1, f2), et l'effet de ligne longue/azimut des éléments horizontaux de l'antenne du système entraîne la propagation des sous-impulsions à des azimuts différents (22, 24). Chaque impulsion émise éclaire ainsi simultanément une pluralité d'azimuts correspondant à la pluralité de sous-impulsions. De cette façon, il est possible d'obtenir un accroissement du nombre d'impulsions dirigées vers une cible potentielle pendant chaque rotation de l'antenne, depuis plus d'une direction azimutale et pendant le même intervalle de répétition des impulsions.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8515026 | 1985-06-13 | ||
GB8515026 | 1985-06-13 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1986007467A1 true WO1986007467A1 (fr) | 1986-12-18 |
Family
ID=10580710
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB1986/000347 WO1986007467A1 (fr) | 1985-06-13 | 1986-06-13 | Radar de surveillance a faisceaux multiples |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0229806A1 (fr) |
JP (1) | JPS63501443A (fr) |
GB (1) | GB2177566A (fr) |
WO (1) | WO1986007467A1 (fr) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6750809B1 (en) * | 2003-04-15 | 2004-06-15 | Raytheon Company | High resolution SAR processing using stepped frequency chirp waveform |
CN112789517A (zh) * | 2018-10-05 | 2021-05-11 | 京瓷株式会社 | 电子设备、电子设备的控制方法以及电子设备的控制程序 |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2725031B1 (fr) * | 1984-12-10 | 1996-11-15 | Dassault Electronique | Dispositif pour recreer une image dynamique, a partir d'un radar |
US5659319A (en) * | 1995-12-21 | 1997-08-19 | Cardion, Inc. | Method and apparatus for operating a surface detection surveillance radar using frequency agile pulse transmissions |
JP2004226158A (ja) * | 2003-01-21 | 2004-08-12 | Fujitsu Ten Ltd | Fm−cwレーダ装置 |
JP2006029959A (ja) * | 2004-07-15 | 2006-02-02 | Toshiba Corp | レーダ装置 |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2331037A1 (fr) * | 1975-11-10 | 1977-06-03 | Int Standard Electric Corp | Radar a poursuite et balayage simultanes et a lobes commutes |
EP0132378B1 (fr) * | 1983-07-21 | 1990-01-31 | Nec Corporation | Dispositif radar à balayage avec faisceaux multiples |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NL139602B (nl) * | 1964-05-21 | 1973-08-15 | Hollandse Signaalapparaten Bv | Radarsysteem. |
US3444555A (en) * | 1967-06-06 | 1969-05-13 | Itt | Frequency scanning radar system with improved angular target detection |
GB1229786A (fr) * | 1967-08-21 | 1971-04-28 | ||
FR2523315A1 (fr) * | 1982-03-12 | 1983-09-16 | Thomson Csf | Procede de lever d'ambiguite de mesure de distance et radar utilisant ce procede |
GB2134741B (en) * | 1983-01-31 | 1987-07-01 | Decca Ltd | Radar apparatus |
-
1986
- 1986-06-13 JP JP50355986A patent/JPS63501443A/ja active Pending
- 1986-06-13 EP EP19860904233 patent/EP0229806A1/fr not_active Withdrawn
- 1986-06-13 WO PCT/GB1986/000347 patent/WO1986007467A1/fr not_active Application Discontinuation
- 1986-06-13 GB GB08614397A patent/GB2177566A/en not_active Withdrawn
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2331037A1 (fr) * | 1975-11-10 | 1977-06-03 | Int Standard Electric Corp | Radar a poursuite et balayage simultanes et a lobes commutes |
EP0132378B1 (fr) * | 1983-07-21 | 1990-01-31 | Nec Corporation | Dispositif radar à balayage avec faisceaux multiples |
Non-Patent Citations (1)
Title |
---|
International Conference on Radar, 4-12 December 1978, SEE, Paris (FR) G.PFISTER: "Famille des Radars de Serie 320" pages 83-92, voir figure 3,8; pages 84-86, paragraphs "The Series 320 Radar Characteristics" * |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6750809B1 (en) * | 2003-04-15 | 2004-06-15 | Raytheon Company | High resolution SAR processing using stepped frequency chirp waveform |
CN112789517A (zh) * | 2018-10-05 | 2021-05-11 | 京瓷株式会社 | 电子设备、电子设备的控制方法以及电子设备的控制程序 |
Also Published As
Publication number | Publication date |
---|---|
GB8614397D0 (en) | 1986-06-13 |
JPS63501443A (ja) | 1988-06-02 |
EP0229806A1 (fr) | 1987-07-29 |
GB2177566A (en) | 1987-01-21 |
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