CN111693933B - Radar signal instantaneous wide-azimuth direction finding system - Google Patents
Radar signal instantaneous wide-azimuth direction finding system Download PDFInfo
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- CN111693933B CN111693933B CN202010561140.1A CN202010561140A CN111693933B CN 111693933 B CN111693933 B CN 111693933B CN 202010561140 A CN202010561140 A CN 202010561140A CN 111693933 B CN111693933 B CN 111693933B
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- 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
- G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
- G01S3/02—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
- G01S3/14—Systems for determining direction or deviation from predetermined direction
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- 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
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
- Y02A90/10—Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation
Abstract
The invention relates to a radar signal instantaneous wide-azimuth direction finding system, which is used for carrying out antenna segmentation on 0.38GHz-18GHz according to four frequency bands and is divided into 0.38GHz-0.8GHz frequency band, 0.8GHz-2GHz frequency band, 2GHz-6GHz frequency band and 6GHz-18GHz frequency band; such a frequency band division design is advantageous for achieving antenna linewidth beam azimuth coverage and high gain reception. 4 different direction-finding array base line designs are adopted, and the direction-finding precision and the successful ambiguity resolution probability within 120 degrees are improved. The problem that the target signal is lost is solved, the problem of complex system structure is solved, and the problem of high system cost is solved.
Description
Technical Field
The invention relates to the field of radar direction finding, in particular to a radar signal instantaneous wide-azimuth direction finding system.
Background
For the instantaneous 120-degree direction finding of radar signals in the wide frequency range of 0.38GHz-18.0GHz, the prior art is mainly realized in two ways. In the first mode, two direction-finding antenna arrays are adopted to cover 60-degree azimuth respectively, the antenna frequency bands are generally divided into three frequency bands, and the antenna frequency bands are segmented or segmented similarly according to 0.38GHz-2GHz,2GHz-6GHz and 6GHz-18 GHz; the antenna frequency band selection switch is used for selecting and receiving a certain 60-degree direction, a set of direction finding receiver and direction finding processor are used for carrying out direction finding on radar signals in frequency bands, one 60-degree direction finding is finished firstly, then the other 60-degree direction finding is carried out, and time division alternation is carried out sequentially, so that 120-degree azimuth direction finding is realized. In the second mode, two direction-finding antenna arrays are adopted to cover 60-degree azimuth respectively, the antenna frequency bands are generally divided into three frequency bands, and the antenna frequency bands are segmented or segmented similarly according to 0.38GHz-2GHz,2GHz-6GHz and 6GHz-18 GHz; and respectively carrying out 60-degree azimuth simultaneous direction finding on the radar signals by two sets of direction finding receivers and direction finding processors in frequency division, and outputting the direction finding result within the range of 120 degrees after the direction finding result is subjected to fusion processing.
Problems of the prior art:
the first method adopts two sets of direction-finding antenna arrays, a set of direction-finding receiver and a set of direction-finding processor, adopts time-sharing switching to respectively carry out 60-degree range direction finding, thereby realizing 120-degree direction finding of azimuth; the method has the problem that target signals are possibly lost in azimuth interception, the signal loss probability is not lower than 50%, and the method cannot achieve instantaneous direction finding in a strict sense.
In the second mode, two sets of direction-finding equipment are adopted, each set of equipment comprises a direction-finding antenna array, a direction-finding receiver and a direction-finding processor, and the directions of the two sets of equipment are simultaneously measured in a range of 60 degrees, so that the direction-finding in a range of 120 degrees is realized; the problems of complex system structure, high system cost and the like exist.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a radar signal instantaneous wide-azimuth direction finding system, which is used for carrying out antenna segmentation on 0.38GHz-18GHz according to four frequency bands and is divided into 0.38GHz-0.8GHz frequency band, 0.8GHz-2GHz frequency band, 2GHz-6GHz frequency band and 6GHz-18GHz frequency band; such a frequency band division design is advantageous for achieving antenna linewidth beam azimuth coverage and high gain reception. 4 different direction-finding array base line designs are adopted, and the direction-finding precision and the successful ambiguity resolution probability within 120 degrees are improved. The problem that the target signal is lost is solved, the problem of complex system structure is solved, and the problem of high system cost is solved.
The aim of the invention is realized by the following technical scheme:
a radar signal instantaneous wide-azimuth direction-finding system comprises a plurality of direction-finding antenna arrays, a direction-finding receiver and a direction-finding processor, wherein the direction-finding receiver is used for receiving radio frequency signals of the direction-finding antenna arrays;
each direction-finding antenna array consists of a plurality of forward antennas and two shadow-hiding antennas;
the direction-finding receiver comprises a plurality of paths of radio frequency channels, is used for synchronously receiving the same local oscillator sources of the plurality of paths of radio frequency signals of the forward antenna and the shadow hiding antenna and finishing down-conversion;
the direction finding processor consists of a multipath intermediate frequency signal acquisition and preprocessing module, a pulse signal detection module, a multichannel interferometer direction finding module, a two-channel shadow hiding processing module and a direction finding result output module and is used for realizing the fusion processing of pulse frequency, direction finding shadow hiding blurring and forward direction finding results.
Further, the plurality of direction-finding antenna arrays includes:
the antenna array comprises four forward antennas and two shadow antennas, wherein the antenna array comprises 0.4-0.8 GHz;
the antenna array comprises a 0.8-2GHz antenna array consisting of four forward antennas and two shadow antennas;
a 2-6GHz antenna array consisting of five forward antennas and two shadow antennas;
a 6-18GHz antenna array consisting of five forward antennas and two shadow antennas;
the forward antenna and the two shadow antennas are distributed at an included angle of 120 degrees, so that the forward antenna covers 120 degrees to the reconnaissance direction, and the two shadow antennas cover 120 degrees to the other two directions respectively.
Further, the 0.4-0.8GHz antenna array and the 0.8-2GHz antenna array are in the form of back cavity dipole antennas, and comprise reflecting plates and antenna elements which are installed on the reflecting plates in a back-to-back symmetrical mode.
Furthermore, the 2-6GHz antenna array and the 6-18GHz antenna array are in a high-gain wide-beam ridge horn antenna mode, and comprise a coaxial waveguide conversion section, a horn section, a radial mode section and a polarizer which are connected in sequence.
Further, each of the forward antenna and the shadow antenna in the direction-finding antenna array is connected with the direction-finding receiver through a filter, and an antenna frequency band selection switch is connected in series between the direction-finding receiver and each filter and is used for selectively outputting any frequency band radio frequency signal in the 0.4-0.8GHz antenna array, the 0.8-2GHz antenna array, the 2-6GHz antenna array and the 6-18GHz antenna array.
Further, the direction-finding receiver also comprises a calibration source for providing a calibration signal to the system to eliminate amplitude phase errors in the direction-finding channel.
Furthermore, the intermediate frequency signal acquisition and preprocessing module realizes intermediate frequency signal synchronous acquisition and synchronous preprocessing, and digital baseband signals of 6 or 7 channels are obtained after digital DDC and digital filtering.
Further, the two-channel concealment processing module is used for processing the concealment signals from the other two 120-degree azimuth and calculating the signal amplitude of the concealment channel.
Further, the system also comprises a direction finding deblurring method, by comparing the signal amplitude received by the forward antenna and the shadow antenna, it can be judged that the approximate signal is from within a certain 120 DEG, if the forward signal amplitude is higher than the shadow signal amplitude, the signal is from within 120 DEG, if the shadow signal amplitude is higher than the forward signal amplitude, the signal is from the shadow direction, and the direction finding blur is removed.
Further, the forward antennas are arranged on the same straight line, and the following conditions are satisfied:
the arrangement interval of each forward antenna in the 0.4-0.8GHz antenna array is as follows in sequence: 599mm, 727mm, 910mm, total baseline length 2236mm;
the arrangement interval of each forward antenna in the 0.8-2GHz antenna array is as follows in sequence: 282mm, 335mm, 418mm, a total baseline length 1035mm;
the arrangement interval of each forward antenna in the 2-6GHz antenna array is as follows: 296mm, 314.2mm, 345.4mm, 430mm, a total baseline length of 1385.6mm;
the arrangement interval of each forward antenna in the 6-18GHz antenna array is as follows in sequence: 134mm, 140.5mm, 152.8mm, 189mm, total baseline length 616.3mm.
The beneficial effects of the invention are as follows:
(1) The instantaneous 120-degree direction finding is realized for the radar signal of 0.38GHz-18GHz, and the frequency bands of the direction finding antenna are respectively 0.38GHz-0.8GHz, 0.8GHz-2.0GHz, 2GHz-6GHz and 6GHz-18GHz, so that the division can ensure that the gain and the wide azimuth coverage of the antenna are both considered.
(2) The antennas in the frequency bands of 0.38GHz-0.8GHz and 0.8GHz-2.0GHz adopt a back cavity dipole antenna mode, the antennas mainly comprise antenna elements, reflecting plates and antenna covers, 120-degree azimuth beam coverage can be realized in the corresponding working frequency band, and the lowest gain in the 120-degree beam exceeds 2dBi; the 2GHz-6GHz and 6GHz-18GHz frequency band antennas are in the form of wide-beam high-gain ridged horn antennas. The antenna mainly comprises a polarizer, a radial mode section, a horn section and a coaxial band conversion section, and can realize 120-degree azimuth beam coverage in a corresponding working frequency band, and the lowest gain in the 120-degree beam exceeds 6.5dBi.
(3) The forward direction-finding array is arranged according to four working frequency bands. According to the arrangement, the interferometer direction finding algorithm adopted by the system can still realize the successful deblurring probability of more than 98% under the condition of the maximum phase error of 35 degrees.
(4) Each frequency band adopts 2 shadow-hiding antennas, the antenna performance of the shadow-hiding antennas is identical to that of a forward antenna, the shadow-hiding antennas can cover 120-degree azimuth, and the two shadow-hiding antennas are arranged in the other two 120-degree directions, and the arrangement mode is shown in fig. 2. By comparing the signal amplitudes received by the forward antenna and the shadow antenna, it can be determined that the approximate signal is within 120 degrees, the forward signal amplitude is higher than the shadow signal amplitude, which means that the signal is within 120 degrees forward, if the shadow signal amplitude is higher than the forward signal amplitude, the signal is indicated to be from the shadow azimuth, so that the direction finding blur is removed.
Drawings
FIG. 1 is a schematic diagram of a system of the present invention;
FIG. 2 is a schematic diagram of an antenna array;
FIG. 3 is a schematic diagram of the distribution and distance of the front antenna and the shadow antenna;
FIG. 4 is a schematic diagram of a back cavity dipole antenna model;
fig. 5 is a schematic diagram of a high gain wide beam ridged horn antenna model.
Detailed Description
The technical scheme of the present invention is described in further detail below with reference to specific embodiments, but the scope of the present invention is not limited to the following description.
The invention realizes the instantaneous azimuth 120-degree direction finding by a set of direction finding equipment (comprising a set of direction finding antenna array, a set of direction finding receiver and a set of direction finding processor) in a frequency division way. The problem that the target signal is lost is solved, the problem of complex system structure is solved, and the problem of high system cost is solved.
Referring to fig. 1, a radar signal instantaneous wide azimuth direction-finding system comprises a plurality of direction-finding antenna arrays, a direction-finding receiver for receiving radio frequency signals of the direction-finding antenna arrays, and a direction-finding processor connected with the direction-finding receiver;
each direction-finding antenna array consists of a plurality of forward antennas 1 and two shadow-hiding antennas 2;
the direction-finding receiver comprises a plurality of paths of radio frequency channels, is used for synchronously receiving the same local oscillator sources of the plurality of paths of radio frequency signals of the forward antenna 1 and the shadow antenna 2 and finishing down-conversion;
the direction-finding processor consists of a multipath intermediate frequency signal acquisition and preprocessing module, a pulse signal detection module, a multichannel interferometer direction-finding module, a two-channel shadow-hiding processing module and a direction-finding result output module and is used for realizing the fusion processing of pulse frequency, direction-finding shadow-hiding blurring and forward direction-finding results.
On the other hand, the invention adopts 4 different direction finding array base line designs aiming at radar signals in the frequency range of 0.38GHz-18GHz, improves the direction finding precision and the successful ambiguity resolution probability in 120 DEG, namely the direction finding antenna array is divided into a plurality of direction finding antenna arrays according to the frequency range, and the plurality of direction finding antenna arrays comprise:
the antenna array comprises a 0.4-0.8GHz antenna array consisting of four forward antennas 1 and two shadow antennas 2;
a 0.8-2GHz antenna array consisting of four forward antennas 1 and two shadow antennas 2;
a 2-6GHz antenna array consisting of five forward antennas 1 and two shadow antennas 2;
a 6-18GHz antenna array consisting of five forward antennas 1 and two shadow antennas 2;
the forward antenna 1 and the two shadow antennas 2 are distributed at an angle of 120 ° to each other, so that the forward antenna 1 covers 120 ° to the reconnaissance direction and the two shadow antennas 2 cover 120 ° to the other two directions, respectively. The shadow antenna 2 and the front antenna 1 adopt antenna units with completely same functional performance, and the distribution schematic diagram can be shown by referring to fig. 2 and 3, all the front antennas 1 in the same antenna array are parallel to each other and arranged on the same straight line, and the antenna arrays formed by the two shadow antennas 2 and the front antennas 1 are distributed at an included angle of 120 degrees.
The 120-degree azimuth direction finding can be realized in various modes such as circular array direction finding, double 60-degree direction finding combination and the like, but a circular array cannot be selected due to the high gain requirement of the system, and the antenna required to be used by the circular array is an omni-directional antenna, so that the gain of the omni-directional antenna cannot meet the requirement; the double 60-degree direction-finding equipment array is also a common choice, but because two sets of direction-finding equipment are needed, each set of equipment independently realizes 60-degree direction finding, and then the direction-finding results are fused, the complexity and the cost of the system are increased, and the system is unfavorable for users.
The problem of 120 DEG of antenna gain and single antenna coverage azimuth is solved through the front antenna sectional design, the direction finding and array design is carried out on the basis, and through analysis, as the wavelength of a frequency band of 0.38GHz-2.0GHz is relatively long, under the condition of ensuring certain phase tolerance, the forward 120 DEG direction finding can be realized through adopting 4-element linear array arrangement, the requirement of 1 DEG of direction finding precision is met, and two hidden shadow antennas 2 which are the same as the forward antennas 1 are arranged in the other two 120 DEG directions for eliminating direction finding ambiguity; for 2.0GHz-18.0GHz, 5-element linear array arrangement is needed, direction finding phase tolerance is ensured, forward direction 120-degree direction finding is realized, the requirement of direction finding precision of 1-degree is met, two hidden shadow antennas 2 which are identical to the forward antennas are also arranged in the other two 120-degree directions as references, and direction finding ambiguity is eliminated.
More specifically, the forward antennas 1 are arranged on the same straight line, and the relation between the distances is as follows:
the arrangement interval of each forward antenna 1 in the 0.4-0.8GHz antenna array is as follows in sequence: 599mm, 727mm, 910mm, total baseline length 2236mm;
the arrangement interval of each forward antenna 1 in the 0.8-2GHz antenna array is as follows in sequence: 282mm, 335mm, 418mm, a total baseline length 1035mm;
the arrangement interval of each forward antenna 1 in the 2-6GHz antenna array is as follows in sequence: 296mm, 314.2mm, 345.4mm, 430mm, a total baseline length of 1385.6mm;
the arrangement interval of each forward antenna 1 in the 6-18GHz antenna array is as follows in sequence: 134mm, 140.5mm, 152.8mm, 189mm, total baseline length 616.3mm.
On the other hand, the 0.4-0.8GHz antenna array and the 0.8-2GHz antenna array are in the form of back cavity dipole antennas, comprising a reflecting plate 3 and antenna elements 4 which are installed on the reflecting plate 3 in a back-to-back symmetrical manner, and the structures of the antenna elements can be shown by referring to fig. 4, that is, the front antenna 1 and the shadow antenna 2 in the 0.4-0.8GHz antenna array and the 0.8-2GHz antenna array are in the form of back cavity dipole antennas.
In order to realize high gain and instantaneous wide azimuth coverage of 0.38GHz-18.0GHz, the receiving antennas are conventionally realized according to three frequency bands, namely 0.38GHz-2.0GHz, 2.0 GHz-6.0 GHz and 6.0 GHz-18.0 GHz.
If the antenna performance with wide azimuth and high gain is to be realized in the frequency range of 0.38GHz-2.0GHz, the antenna performance mainly comprises a logarithmic period dipole antenna, a broadband horn antenna, an absorption type planar spiral antenna and the like, wherein the broadband horn antenna has larger wave beam width variation in the frequency range and is easy to generate wave beam cracking at the high end of the frequency, and meanwhile, the horn antenna in the frequency range has large size and heavy weight, so that the selection of the antenna is not recommended; the absorption type planar spiral antenna is often used as an antenna unit of a direction-finding array of an interferometer, but because the antenna is filled with wave-absorbing materials in an inner cavity, the gain of the antenna (especially at the low frequency end) is lower, and the antenna is not ideal for long-distance reception; the logarithmic period antenna is used as a typical non-frequency conversion antenna, can theoretically realize frequency coverage of any bandwidth, has stable gain and beam width in a frequency range, and can realize 45-degree inclined linear polarization radiation by placing a radiation oscillator and the ground, thereby being an ideal alternative antenna in the system.
Simulation of the log-periodic antenna in the frequency range of 0.38GHz-2.0GHz shows that the azimuth plane has the widest beam width when the antenna works in a vertical polarization state, the 120-degree edge gain can reach approximately 2dB, but the beam width of the azimuth plane is narrowed and the edge gain is reduced by 10dB when the whole antenna is inclined by 45 degrees to realize oblique polarization radiation. In order to improve the antenna gain on the premise of unchanged azimuth beam width, only narrow beams can be pressed in the pitching direction, namely antenna units are assembled in the pitching direction, and the antenna gain can be improved by 3dB in theory through the two antenna arrays. However, according to the theory of array antennas, the ideal array spacing between unit antennas is generally between 0.6 and 1.2 wavelengths, if the spacing is too small, the gain cannot be improved, and if the spacing is too large, higher side lobes appear, and the radiation of the main lobe of the antenna is affected. Therefore, in the frequency range of 0.38GHz-2.0GHz, the space between the antenna units is difficult to simultaneously consider the high end and the low end of the frequency. In view of this, in order to meet the requirements of antenna beam and gain, the antenna can be operated only in two frequency bands, namely, 0.38GHz-0.8GHz and 0.8GHz-2.0 GHz.
According to the above analysis, since the antenna of 0.38GHz-2.0GHz needs to be operated in two frequency bands, the respective bandwidths thereof are greatly reduced from 5:1 bandwidths to 2.1:1 and 2.5:1 bandwidths. Under such conditions, the antenna element has a better choice, namely a cavity-backed dipole antenna. The back cavity dipole antenna is essentially a half-wavelength dipole antenna, and the antenna unit can work in a frequency range close to 3:1 through the treatment of widening a radiation sheet and balanced feeding, and the antenna gain can be improved by adding the reflective metal back cavity. Meanwhile, the antenna units are assembled on the nodding surface, so that the gain on the azimuth surface can be integrally improved by 3dB, and the index requirement is met. Compared with the logarithmic period antenna, the back cavity dipole antenna has the greatest advantage that the size is larger, and the radial direction of the logarithmic period antenna is provided with a plurality of vibrators working in different frequency bands, so that the radial direction of the logarithmic period antenna is larger, the radial direction of the logarithmic period antenna working in 0.38GHz-0.8GHz is larger than 550mm, and the back cavity dipole antenna in the same frequency band is only 220mm, so that the space occupied by the antenna can be greatly reduced, and meanwhile, the weight of the antenna is also reduced.
The 2-6GHz antenna array and the 6-18GHz antenna array adopt a high-gain wide-beam ridge horn antenna form, and comprise a coaxial waveguide conversion section 5, a horn section 6, a radial mode section 7 and a polarizer 8 which are sequentially connected, and the structure of the horn antenna array can be shown by referring to figure 5. The radial mode section 7 is in a planar structure, the polarizer 8 is designed into a circular arc shape, and the radial mode horn-radiated electromagnetic wave is converted into oblique polarization or circular polarization from horizontal polarization so as to adapt to radar signal polarization diversity, namely, the forward antenna 1 and the shadow antenna 2 in the 2-6GHz antenna array and the 6-18GHz antenna array are both in a back cavity dipole antenna mode.
The antenna with two frequency bands of 2.0 GHz-6.0 GHz and 6.0 GHz-18.0GHz is easy to think about using a horn antenna in order to realize 120-DEG wide-beam high gain in a bandwidth of 3:1, but the conventional horn antenna cannot meet the requirement, and the horn antenna needs to be improved. Firstly, the working bandwidth of the horn antenna is widened by a waveguide-horn internal ridging method, secondly, the size of the mouth surface of the horn is required to be adjusted, the size of the azimuth plane direction is reduced, the beam is as wide as possible, meanwhile, the size of the pitching plane is required to be increased as much as possible to ensure the gain, higher gain is realized by a method of compressing the pitching plane beam, finally, in order to ensure that the azimuth plane directional diagram in the frequency band does not have large fluctuation in the range of the wide beam, a radial mode transmission section is introduced at the mouth surface of the horn, and other higher modes are restrained by exciting a main mode TE10, so that the uniform distribution of the mouth surface field of the azimuth plane direction is ensured.
Because the electromagnetic wave radiated by the horn antenna is linearly polarized, the polarization direction of the electromagnetic wave is consistent with the direction of an electric field radiated by the horn, if 45-degree oblique polarization is to be realized, the most direct method is to rotate the horn antenna by 45 degrees like a 0.38GHz-2.0GHz antenna, but the beam width of an azimuth plane is greatly reduced. Therefore, under the condition that the beam width of the horn is unchanged, a polarization cover (namely a polarizer 8) is added in front of the antenna radiation port, and the polarization cover has the function of converting electromagnetic waves radiated by the radial mode horn from horizontal polarization into oblique polarization or circular polarization so as to adapt to the polarization diversity of radar signals. Meanwhile, the shape of the polarizer is required to be consistent with the shape of the radial mode radiation section of the horn, so that electromagnetic waves radiated by the horn can be uniformly irradiated on the polarizer, and the inclined polarizer can be ensured not to influence the radiation beam of the horn antenna.
On the other hand, each of the forward antenna 1 and the shadow antenna 2 in the direction-finding antenna array is connected with a direction-finding receiver through a filter respectively, and an antenna frequency band selection switch is connected in series between the direction-finding receiver and each filter and is used for selectively outputting any frequency band radio frequency signals in the 0.4-0.8GHz antenna array, the 0.8-2GHz antenna array, the 2-6GHz antenna array and the 6-18GHz antenna array.
In another aspect, the direction-finding receiver further comprises a calibration source for providing a calibration signal to the system to eliminate amplitude phase errors in the direction-finding channel. The intermediate frequency signal acquisition and preprocessing module realizes intermediate frequency signal synchronous acquisition and synchronous preprocessing, and digital baseband signals of 6 or 7 channels are obtained after digital DDC and digital filtering. The two-channel shadow processing module is used for processing the shadow signals from the other two 120-degree azimuth and calculating the signal amplitude of the shadow channel.
In another aspect, the system further includes a direction finding deblurring method, by comparing the signal amplitudes received by the forward antenna and the shadow antenna, it can be determined that the approximate signal is within 120 ° of the forward signal amplitude, and if the forward signal amplitude is higher than the shadow signal amplitude, it indicates that the signal is within 120 ° of the forward direction, and if the shadow signal amplitude is higher than the forward signal amplitude, it indicates that the signal is from the shadow direction, so as to remove the direction finding blur.
Description of working principle:
for the instantaneous 120-degree direction finding of radar signals in the frequency range of 0.38GHz-18GHz, the method is realized through two steps; firstly, direction finding calibration is carried out, and then direction finding is carried out.
When the system is started, the system is automatically started or the direction-finding calibration is started through manual setting, a calibration source is started, and a certain frequency point calibration signal is output; an antenna frequency band selection switch selects an input signal from the calibration channel; the radio frequency receiving channel completes homologous radio frequency receiving of 6 or 7 channels, and the channel selects and outputs intermediate frequency signals according to the correspondence with the frequency band; the intermediate frequency signal acquisition and preprocessing module completes synchronous acquisition and preprocessing of 6 or 7 intermediate frequency signals and outputs baseband signals; the pulse signal detection module completes signal detection and calculates the frequency of the received signal; the multichannel interferometer direction finding module detects amplitude values of reference channels and calculates phase differences among 4 or 5 forward channels when in a direction finding calibration mode; the two-channel shadow processing module is used for detecting the signal amplitude of the shadow channel; the direction finding result output module calculates the forward channel phase difference and the amplitude difference between the reference channel and the shadow hiding channel under the set frequency, and establishes an amplitude-phase calibration table; after the calibration of one frequency point is completed, the calibration of the next frequency point is sequentially carried out until the whole frequency band is traversed, and the full-frequency band calibration table is completed.
After the calibration flow is executed, the system is switched to a normal direction-finding mode, a calibration source is closed, the system receives radar electronic radio frequency signals in frequency bands of 0.38GHz-0.8GHz, 0.8GHz-2GHz, 2GHz-6GHz and 8GHz-18GHz respectively through an automatic or manual setting mode, the radar electronic radio frequency signals in one frequency band are output after being respectively filtered through the frequency bands, the radar signals in one frequency band are selected through an antenna frequency band selection switch, 6 or 7 channel radio frequency homologous reception is finished through a radio frequency channel, an intermediate frequency signal is output, the intermediate frequency signal synchronous acquisition and synchronous pretreatment are finished through an intermediate frequency signal acquisition and pretreatment module, the pulse signal detection of a reference channel is finished through a pulse signal detection module, and the signal frequency is extracted; based on a direction-finding calibration meter, the multichannel interferometer direction-finding module adopts an interferometer direction-finding principle to realize the calculation of the incoming wave direction of the radar pulse signal in the forward 120 degrees and obtain the amplitude value of the reference channel signal; the two-channel shadow processing module calculates the amplitude value of the radar pulse signal in the shadow channel; the direction finding result output module compares amplitude values of the reference channel and the shadow channel, eliminates the influence of incoming wave signals within 120 degrees in the non-forward direction, and outputs the real direction finding result of radar signals within 120 degrees in the forward direction by utilizing the frequency finding result, the shadow signal elimination result and the forward direction finding result.
The foregoing is merely a preferred embodiment of the invention, and it is to be understood that the invention is not limited to the form disclosed herein but is not to be construed as excluding other embodiments, but is capable of numerous other combinations, modifications and environments and is capable of modifications within the scope of the inventive concept, either as taught or as a matter of routine skill or knowledge in the relevant art. And that modifications and variations which do not depart from the spirit and scope of the invention are intended to be within the scope of the appended claims.
Claims (9)
1. The radar signal instantaneous wide-azimuth direction-finding system is characterized by comprising a plurality of direction-finding antenna arrays, a direction-finding receiver and a direction-finding processor, wherein the direction-finding receiver is used for receiving radio-frequency signals of the direction-finding antenna arrays, and the direction-finding processor is connected with the direction-finding receiver;
each direction-finding antenna array consists of a plurality of forward antennas (1) and two shadow hiding antennas (2);
the direction-finding receiver comprises a plurality of paths of radio frequency channels, is used for synchronously receiving the same local oscillator sources of the plurality of paths of radio frequency signals of the forward antenna (1) and the shadow antenna (2) and finishing down-conversion;
the direction finding processor consists of a multipath intermediate frequency signal acquisition and preprocessing module, a pulse signal detection module, a multichannel interferometer direction finding module, a two-channel shadow hiding processing module and a direction finding result output module, and is used for realizing the fusion processing of pulse frequency, direction finding shadow hiding blurring and forward direction finding results;
the fusion treatment is as follows: receiving radar electronic radio frequency signals, and extracting signal frequencies; calculating the incoming wave direction of a radar pulse signal within 120 degrees in the forward direction, and obtaining the signal amplitude value of a reference channel; calculating the amplitude value of the radar pulse signal in the shadow channel; comparing amplitude values of the reference channel and the shadow channel, eliminating influence of incoming wave signals within 120 degrees in a non-forward direction, and outputting a direction finding result of a radar signal within a real forward direction 120 degrees range by utilizing a frequency finding result, a shadow signal eliminating result and a forward direction finding result;
the plurality of direction finding antenna arrays includes:
the antenna array comprises four forward antennas (1) and two shadow-hiding antennas (2) and is 0.4-0.8 GHz;
the antenna array comprises a 0.8-2GHz antenna array consisting of four forward antennas (1) and two shadow-hiding antennas (2);
the antenna array comprises a 2-6GHz antenna array consisting of five forward antennas (1) and two shadow-hiding antennas (2);
the antenna array comprises a 6-18GHz antenna array consisting of five forward antennas (1) and two shadow-hiding antennas (2);
the forward antenna (1) and the two shadow-hiding antennas (2) are distributed at an included angle of 120 degrees relative to each other, so that the forward antenna (1) covers 120 degrees to the reconnaissance direction, and the two shadow-hiding antennas (2) respectively cover 120 degrees to the other two directions.
2. The radar signal instantaneous wide azimuth direction finding system according to claim 1, wherein the 0.4-0.8GHz antenna array and the 0.8-2GHz antenna array are in the form of back cavity dipole antennas, comprising a reflecting plate (3), and antenna elements (4) mounted back-symmetrically on the reflecting plate (3).
3. The radar signal instantaneous wide-azimuth direction-finding system according to claim 2, wherein the 2-6GHz antenna array and the 6-18GHz antenna array are in the form of high-gain wide-beam ridged horn antennas, and comprise a coaxial waveguide conversion section (5), a horn section (6), a radial mode section (7) and a polarizer (8) which are connected in sequence.
4. A radar signal instantaneous wide-azimuth direction-finding system according to claim 3, wherein each of the forward antenna (1) and the shadow antenna (2) in the direction-finding antenna array is connected with a direction-finding receiver through a filter, and an antenna frequency band selection switch is connected in series between the direction-finding receiver and each filter, and is used for selectively outputting any frequency band radio frequency signal in the 0.4-0.8GHz antenna array, the 0.8-2GHz antenna array, the 2-6GHz antenna array and the 6-18GHz antenna array.
5. The radar signal instantaneous wide-azimuth direction-finding system of claim 4, wherein the direction-finding receiver further comprises a calibration source for providing a calibration signal to the system to eliminate amplitude phase errors in the direction-finding channel.
6. The radar signal instantaneous wide-azimuth direction-finding system according to claim 5, wherein the intermediate frequency signal acquisition and preprocessing module is used for realizing intermediate frequency signal synchronous acquisition and synchronous preprocessing, and obtaining digital baseband signals of 6 or 7 channels after digital DDC and digital filtering.
7. The radar signal instantaneous wide-azimuth direction-finding system of claim 6, wherein the two-channel concealment processing module implements concealment signal processing from two other 120 ° azimuths to calculate concealment channel signal amplitudes.
8. The radar signal instantaneous wide-azimuth direction-finding system according to any one of claims 1-6, further comprising a direction-finding deblurring method, wherein the direction-finding deblurring method is used for comparing the signal amplitudes received by the forward antenna and the shadow antenna to determine that the approximate signal is within 120 ° and that the forward signal amplitude is higher than the shadow signal amplitude, wherein the signal is within 120 ° of the forward direction, and wherein if the shadow signal amplitude is higher than the forward signal amplitude, the signal is from the shadow azimuth, so that the direction-finding blur is removed.
9. The radar signal instantaneous wide azimuth direction-finding system according to claim 8, wherein the forward antennas (1) are arranged on the same line and satisfy:
the arrangement interval of each forward antenna (1) in the 0.4-0.8GHz antenna array is as follows in sequence: 599mm, 727mm, 910mm, total baseline length 2236mm;
the arrangement interval of each forward antenna (1) in the 0.8-2GHz antenna array is as follows in sequence: 282mm, 335mm, 418mm, a total baseline length 1035mm;
the arrangement interval of each forward antenna (1) in the 2-6GHz antenna array is as follows in sequence: 296mm, 314.2mm, 345.4mm, 430mm, a total baseline length of 1385.6mm;
the arrangement interval of each forward antenna (1) in the 6-18GHz antenna array is as follows in sequence: 134mm, 140.5mm, 152.8mm, 189mm, total baseline length 616.3mm.
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