GB2250152A - Radar with multiple beams - Google Patents
Radar with multiple beams Download PDFInfo
- Publication number
- GB2250152A GB2250152A GB8403181A GB8403181A GB2250152A GB 2250152 A GB2250152 A GB 2250152A GB 8403181 A GB8403181 A GB 8403181A GB 8403181 A GB8403181 A GB 8403181A GB 2250152 A GB2250152 A GB 2250152A
- Authority
- GB
- United Kingdom
- Prior art keywords
- radar
- signals
- bearing
- antenna
- map
- Prior art date
- Legal status (The legal status 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 status listed.)
- Granted
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
- 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
- G01S7/38—Jamming means, e.g. producing false echoes
-
- 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
- G01S13/46—Indirect determination of position data
- G01S13/48—Indirect determination of position data using multiple beams at emission or reception
-
- 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
-
- 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
- G01S7/021—Auxiliary means for detecting or identifying radar signals or the like, e.g. radar jamming signals
-
- 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
- G01S7/42—Diversity systems specially adapted for radar
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- 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
A radar apparatus has a multiple beam antenna 10 producing angularly spaced beams. Separate broad band receivers 13 are associated with respective beams and supply received signals to an RF environment store 17 which maps the frequency and bearing of the signals. A radar transmitter 19 generates radar signals of selected frequency and these are supplied by a beam selector 15 to one of the beams of the antenna. An adaptive controller 23 controls the frequency selection of the radar signals for the selected antenna beam, in response to the map in the store 17 so as to improve radar performance, e.g. by avoiding jamming signal frequencies. The beam selector 15 may transmit on all antennae in sequence at the selected frequencies or may select the order of the antennae as well as their frequencies, in dependence on the map store. <IMAGE>
Description
RADAR APPARATUS
The present invention is concerned with radar apparatus.
It is known to provide both radar apparatus and electronic surveillance measures (ESM) apparatus on mobile weapons platforms such as ships, aircraft or land vehicles. However, these are normally embodied by separate apparatus, one operating as active radar and the other monitoring the radio frequency (RF) environment to provide ESM functions. The present invention is primarily concerned with providing a combined apparatus giving both radar and ESM functions and also permitting the use of
ESM information to optimise the radar function.
According to the present invention, radar apparatus comprises a multiple beam antenna having a plurality of independent feeds for a corresponding plurality of angularly spaced beams defining bearings over a predetermined angular sector, a plurality of broad band receivers associated with said feeds and arranged for simultaneously receiving signals from respective said angularly spaced beams, RF environment store means responsive to received signals from said broad band receivers to provide a real time map of the frequency and bearing of the received signals, radar transmitter apparatus to generate signals of selected frequency characteristics, beam selecting means to select at least one of said antenna feeds for supply thereto of said radar signals, and adaptive control apparatus responsive to the stored map of received signals in the RF environment store means to provide real time control of the selection of said radar signal frequency characteristics to improve the performance of the radar apparatus. By this apparatus, the emission of radar signals for active radar operation can be flexibly controlled in real time response to the existing RF environment. Alternatively, the radar can be controlled in response to a good forecast of the immediate future RF envinz=ent based on statical analysis of the recent history.
Thus the fnpyency of the radar emissions can be selected for any particular bearing to be those which are relatively free, for example, of any jamming signals at that bearing.
Conummently the beam selecting means is arranged to select the antenna feeds in a predetermined sequence and said adaptive control apparatus is responsive to signals indicative of the defined bearing of the beam corresponding to the selected feed to control the selection of radar signal fre w ncy characteristics in dependence cn the mapped received signal frequencies at the defined bearing held in the store means, so as to improve expected radar perforttanoe at the defined bearing.For example, the beam selecting means may be arranged to select the antenna be arts in azimuth sequenoe thereby approximating the usual azimuth scanning radar beam.
However, in an alternatise arrangement said adaptive ccntrol apparatus includes means for generating radar bearing control signals to provide real time control of the selection of the bearing of the radar beam emitted by the antenna in response to the stored RF enviraitrent map, and the beam selecting means is then capable of rlesponding to said bearing control signals to select correspcnding antenna feeds. With this alternative arrangement, not only the frequency but also the bearing of the radar bean can be adaptively selected in respcnse to the real time RF environment map.Thus, the radar can be arranged to "look" on bearings which become free of jamming only temporarily, during these quiet periods. This can all be dme automatically and substantially in real time, whilst meeting a need to service and ppdate targets already detected and re-examining jarred arcs on the optimum frequency.
In a further preferred embodiment, the apparatus includes a plurality of said radar transmitter apparatus controllable by the adaptive control apparatus to emit simultaneously radar beams at different selected bearings and with different selected frequency characteristics.
Such an arrangement provides greatly increased flexibility of the radar apparatus enabling several different beams to be emitted at the same time and at different frequencies, all controlled to make optimum use of the radio frequency spectrum in the light of the existing environment. In this way, the radar can automatically put transmission pulses in a quiet band on a particular bearing at any time, including during the usual look through time of an intelligent jammer.
Examples of the present invention will now be described with reference to the accompanying drawings in which,
Figure 1 is a block schematic diagram of radar apparatus embodying the present invention;
Figure 2 is a block schematic diagram illustrating in more detail the environment mapping and adaptive control systems shown in Figure 1; and
Figure 3 is a graphical representation of the operation of the apparatus.
Referring firstly to Figure 1, apparatus is shown including a multiple beam antenna system 10. The antenna system 10 has a plurality of independent feeds 11 with each feed corresponding to a respective angularly spaced beam from the antenna system. The antenna system 10 may be embodied in various different ways. For example, a relatively crude multiple beam antenna may comprise a circular array of outwardly directed horn antennas with each horn having a respective independent feed.
However, in a preferred arrangement, the antenna system comprises a 3600 parabolic -torus reflector formed of parallel wired elements at 450 with the vertical meridians of the reflector. The multiple radar beams are then formed by a circular array of independent feed horns pointing outwardly on the focal circle of the parabolictorus reflector. An arrangement of this kind is shown at page 282 of- the 1962 edition of Introduction to Radar
Systems by M.I.Skolnik. In an antenna system of this kind incorporated in the present invention, each feed horn around the focal circle of the reflector is fed independently from the radar apparatus.
Preferring to Figure 1, each feed horn 11 is fed independently to a respective circulator 12. Thus if there are a total of N feed horns in the antenna system, these are fed to corresponding ports on a total of N circulators 12. One of the other ports of the circulators 12 are each fed independently to respective wide band
ESM receivers 13, via microwave protection switches 14.
Further ports on the ciroulators 12, are fed independently to a respective one of a total of N outlets of a multiway microwave switch 15. The microwave switch 15 is arranged to connect a selected one of the circulator 12 to radar receiver and transmitter apparatus 16.
It will be appreciated fran Figure 1 that the radio frequency signals reoeid in each of the beams of the antenna system, via corresponding feed horns 11 and circulators 12, are revived sittul- taneously in corresponding wide band ESM reivers 13.The switches 14 are normally closed and seize only to block RF signals reaching the receivers during output pulses of the radar transmitter in the apparatus 16. Alternatiwly, each ESM receiver may include a steerable rejection notch to block only the radar transmission pulse frequancy, thus allowing listening through cn the other frequencies. This frequency selection process is further aided by the directivity of the different beams.
The ESM receivers process the received radio frequency signals on each bearing in dependently, performing the usual spectrum analysis of these signals. The resultant information is fed from the receivers 13 for all bearings to an azfimuth/frequency map store 17 which is continuously updated to provide a map of the frequencies of received signals at each of the different bearings, corresponding to the beams of the antenna system, at all times.
In the radar receiver and transmitter apparatus 16, the selected feed horn 11 is connected via its corresponding circulator 12 and the radio frequency switch 15 to a further circulator 18.
One port of the circulator 18 is supplied with radar transmitter pulses from a broad band frequency agile transmitter 19. Another port of circulator 18 supplies received radar signals via a Transmit/Receive cell or switch 20 to a radar receiver 21. Normal radar video is then supplied on an output line 22. The broad band frequency agile transmitter 19 of the radar apparatus is controlled by signals from an adaptive radar control unit 23. The adaptive radar control unit 23 is itself responsive to indications from the azimuth/ frequency map store 17 and also from the radio frequency switch 15 to control the broad band agile transmitter 19 to generate radar pulses at frequencies which are, on the respective bearing, substantially clear of received noise or jamming signals.Thus, the adaptive radar control unit 23 accesses data from the map store 17, identifying the frequencies of received signals on the bearing as indicated by the feed selected by the switch 15. In this way, the radar apparatus is controlled automatically to emit radar pulses at a frequency which is substantially clear of received noise or jamming. Since the map store 17 is updated substantially in real time, the radar apparatus responds immediately to changes in the radio frequency environment thereby optimising performance.
Figure 2 shows the map store 17 and adaptive control unit 23 in greater detail. Signals from the wide band
ESM receivers 13 are fed to a multi channel spectrum analyser 30 which has one channel for each feed of the antenna system, ie each beam. The output indications from the analyser 30 are then stored in a real time store which logs the frequencies of received signals against the azimuth of the corresponding beam. The resultant real time map of the radio frequency environment can be displayed on an azimuth/frequency real time display 32.
A radar clear channel selector 33 accesses the stored information in the store 31 and defines therefrom clear channels which are substantially free of received noise or other signals. Radar control 34 employs the clear channel indications from the selector 33 for a particular radar beam azimuth, as indicated by signals on a line 35 from the radio frequency switch 15, to control a radar frequency drive unit 36 to generate appropriate frequency signals for the radar transmitter. The radar transmitter is formed as a broad band high power amplifier amplifying the frequency signals generating by the drive 36.
In addition, Figure 2 shows that the apparatus provides simultaneously from the same antenna system the usual functions of ESM. Thus, an ESM data processor 37 accesses data from the real time store 31 providing data to a target correlator 38. The target correlator 38 receives target indications from a passive target plotter 39 which also accesses data in the real time store 31.
The passive target plotter is capable of identifying targets which are themselves emitters of radio frequency signals. The bearing of such targets can be identified from the single apparatus illustrated in Figures 1 or 2, but an indication of the position of such targets can be further identified by correlating the signals from two sets of apparatus which are some distance apart in space.
Additionally, radar video from the radar receiver 21 is supplied to a radar field store 40 which contains a store of all the radar return signals during the preceding complete azimuth scan of the radar beam. The radar video signals are also supplied directly to a radar display unit 41.
A radar target plotter 42 accesses data in the radar field store 40 to identify target plots and supplies such radar target information also to the target correlator 38.
In the correlator 38, such radar target plots are correlated with indications from the ESM data processor 37 and the passive target plotter 39 to provide more detailed information on the targets by relating the radar targets with any jamming emissions detected by the ESM system. A target jamming status indicator 43 can provide data defining the likely importance of detected targets in accordance with the degree of jamming being used to protect their position.
Data from the target correlator 38, the target jamming status indicator 43 and also the radar target plotter 42 is all supplied to a target best estimate display 44 which can provide a display of all targets discerned by the combined system, giving each target varying degrees of threat indication etc.
A clutter map 45 is also supplied with the information fram the radar field store 40 to build up a map of the radar clutter signals received by the apparatus. The plotter map 45 can supply signals to the radar display 41 to generate on the display a map of the clutter when required.
Figure 3 shows graphically the manner in which the radar apparatus described above can make best use of the available radio frequency spectrum in a hostile radio frequency environment. In the arrangement of Figure 3, it is assumed that the radio frequency switch 15 switches between the feeds to the antenna system in a cyclic sequence corresponding to rotation of the radar beam. Thus, one complete period of rotation of the radar beam as indicated along the x-axis of the upper graph in Figure 3 corresponds to 3600 of azimuth scan. Throughout the azimuth scanning of the radar system, signals from all bearings are being received in the various ESM receivers so that the map is being continually updated in the real time store of the frequencies of received signals against the bearing. The second graph from the top of Figure 3 is a simplified indication of such an ESM map.In the example shown in Figure 3, both the azimuth and the frequency defihition is relatively crude. Nevertheless, in the map, the shaded blocks are intended to indicate regions of the frequency/azimuth space which are occupied by received signals, typically jamming signals. The lower graph on Figure 3 is the inverse of the middle graph so that the shaded portion indicates those parts of the frequency/azimuth space which would be available for radar operation. It will be appreciated that in practice with an azimuth scanning radar only the portion of the map at the bearing being scanned by the radar at any time is used to control the emission frequency of the radar system.
In an alternative embodiment of the invention, both the frequency of the radar emissions and the direction of the radar beam can be subject to the automatic control.
With such an arrangement the radar apparatus is no longer constrained to the usual rotational azimuth scan but instead can "look" at successive bearings in any sequence.
With such an arrangement, the radar could look on a selected bearing in real time response to the ESM receiver for that bearing during the dead times of a jammer on that bearing.
Furthermore, another development of the present invention provides a plurality of broad band agile transmitters cbrresponding to transmitter 19 with each transmitter being controllably connected to a respective one of the antenna feeds. In this way, multiple radar transmitter beams can be emitted simultaneously in different azimuth directions. It will be appreciated that the wide band ESM receivers may themselves operate as the radar recevers, enabling simultaneous reception of radar returns on different beams. Still further, it will be appreciated that the apparatus described above can be used itself as a jammer. The radar transmitter or transmitters can be arranged to emit appropriate jamming signals on selective bearings as required.The frequencyagile radar transmitter envisaged for use in the apparatus of the present invention is especially useful and convenient as a source of jamming emissions.
In summary therefore it can be appreciated that apparatus of the form described above can provide in combination the advantages of a wide band omnidirectional electronic surveillance measures receiver, an adaptively responding radar apparatus controlled in response to the existing radio environment to optimise performance, and also an intelligent jammer emitting jamming signals, again in adaptive response to the radio environment and also enabling optimised performance of the friendly radar.
In addition the passive plotter can keep track of the bearing of targets which are themselves emitting and which have already been detected (in range and bearing) by the radar. For example, the emissions of navigational aid systems or fire control radars on target vehicles can be tracked in bearing for a period following active radar detection, and such tracks can then be updated by active radar (to resolve range uncertainty) relatively infrequently.
Claims (5)
1. Radar apparatus comprising a multiple beam antenna having a plurality of independent feeds for a corresponding plurality of angularly spaced beams defining bearings over a predetermined angular sector, a plurality of broad band receivers associated with staid feeds and arranged for simultaneously receiving signals from respective said angularly spaced beams, RF environment store means responsive to received signals from said broad band receivers to provide a real time map the frequency and bearing of the received signals, radar transmitter apparatus to generate radar signals of selected frequency characteristics beam selecting means to select at least one of said antenna feeds for supply thereto of said radar signals, and adaptive control apparatus responsive to the stored map of received signals in the RF environment store means to provide real-time controlefthe selection of said radar signal frequency characteristics to improve the performance of the radar apparatus.
2. Radar apparatus as claimed in Claim 1 wherein the beam selecting means is arranged to select the antenna feeds in a predetermined sequence and said adaptive control apparatus is responsive to signals indicative of the defined bearing of the beam corresponding to the selected feed to control the selection of radar signal frequency characteristics in dependence on the mapped received signal frequencies at the defined bearing held in the store means, so as to improve expected radar performance at the defined bearing.
3. Radar apparatus as claimed in Claim 1 wherein said adaptive control apparatus includes means for generating radar bearing control signals to provide real time control of the selection of the bearing of the radar beam emitted by the antenna in response to the stored
RF environment map, and the beam selecting means is capable of responding to said bearing control signals to select corresponding antenna feeds.
4. Radar apparatus as claimed in Claim 3 and including a plurality of said radar transmitter apparatus controllable by the adaptive control apparatus to emit simultaneously radar beams at different selected bearings and with different selected frequency characteristics.
5. Radar apparatus as claimed in Claims 3 or 4, wherein the or each said radar transmitter apparatus is additionally controlled to generate jamming signals for emission by the apparatus on selected bearings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8403181A GB2250152B (en) | 1984-02-08 | 1984-02-08 | Radar apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8403181A GB2250152B (en) | 1984-02-08 | 1984-02-08 | Radar apparatus |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2250152A true GB2250152A (en) | 1992-05-27 |
| GB2250152B GB2250152B (en) | 1992-10-21 |
Family
ID=10556200
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8403181A Expired - Fee Related GB2250152B (en) | 1984-02-08 | 1984-02-08 | Radar apparatus |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2250152B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0803070A2 (en) * | 1995-01-09 | 1997-10-29 | Northrop Grumman Corporation | Radar signal selection based upon antenna bearing |
| RU2573822C2 (en) * | 2014-05-20 | 2016-01-27 | Открытое акционерное общество "НИИ измерительных приборов-Новосибирский завод имени Коминтерна" (ОАО "НПО НИИИП-НЗиК") | Method of protecting surveillance radar station with phased antenna array from interference |
| FR3058577A1 (en) * | 2016-11-10 | 2018-05-11 | Thales | RECEIVING DEVICE FOR ELECTRONIC SCAN ANTENNA FOR FUNCTIONING IN RADAR MODE AND RESM, AND RADAR EQUIPPED WITH SUCH A DEVICE |
-
1984
- 1984-02-08 GB GB8403181A patent/GB2250152B/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0803070A2 (en) * | 1995-01-09 | 1997-10-29 | Northrop Grumman Corporation | Radar signal selection based upon antenna bearing |
| EP0803070A4 (en) * | 1995-01-09 | 1998-04-15 | Northrop Grumman Corp | Radar signal selection based upon antenna bearing |
| RU2573822C2 (en) * | 2014-05-20 | 2016-01-27 | Открытое акционерное общество "НИИ измерительных приборов-Новосибирский завод имени Коминтерна" (ОАО "НПО НИИИП-НЗиК") | Method of protecting surveillance radar station with phased antenna array from interference |
| FR3058577A1 (en) * | 2016-11-10 | 2018-05-11 | Thales | RECEIVING DEVICE FOR ELECTRONIC SCAN ANTENNA FOR FUNCTIONING IN RADAR MODE AND RESM, AND RADAR EQUIPPED WITH SUCH A DEVICE |
| EP3321711A1 (en) * | 2016-11-10 | 2018-05-16 | Thales | Receiving device for electronic scanning antenna capable of operating in radar and resm mode, and radar provided with such a device |
| US10571549B2 (en) | 2016-11-10 | 2020-02-25 | Thales | Receiving device for an electronically scanned antenna, said device being able to operate in RESM and radar mode, and radar equipped with such a device |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2250152B (en) | 1992-10-21 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19930121 |