A phased array radar multi-beam forming method based on FPGA

Abstract

The application provides a phased array radar multi-beam forming method based on FPGA, which comprises the following steps: obtaining initial information; determining the transmission control code of the final array antenna unit in response to the received instruction; generating an intermediate frequency signal and frequency conversion processing to form a radio frequency signal by using the FPGA; changing the initial phase of the radio frequency signal according to the transmission control code; determining the receiving control code of the final array antenna unit by using the receiving beam pointing code information and the corresponding receiving unit initial phase code; generating a receiving radio frequency signal when the array antenna unit receives a signal; converting the receiving radio frequency signal into a digital signal through processing; generating multiple groups of phase feeding gradients, namely the weight values of the receiving and beams, in response to different pointing information in the received instruction; and giving the weight values of different groups of receiving and beams in the digital signal to form multiple groups of receiving and beams. According to the wave position scanning mode, the single wave position covers a wider space range and consumes less time under the space domain.

Description

Technical Field

[0001] This invention relates to the field of phased array radar technology, and in particular to a multi-beamforming method for phased array radar based on FPGA. Background Technology

[0002] Phased array radar is an electronically scanned array radar that achieves beam pointing by changing the initial phase of the transmitting elements. Compared to traditional radar, it does not rely on mechanical rotation during scanning, achieving rapid beam scanning. Digital phased array radar is a radar technology that uses digital means to achieve waveform transmission and reception. Compared to traditional radar, it can use weighted processing of elements to control beam pointing and suppress sidelobe levels.

[0003] Currently, there are two main types of multi-beamforming methods for phased array radars: time-division multi-beamforming and aperture-division multi-beamforming. The first method consumes more time and resources and results in lower radar accuracy; the second method reduces radar angular accuracy while sacrificing radar range. Summary of the Invention

[0004] The technical problem to be solved by the present invention is how to make the single beam coverage of phased array radar wider, thereby reducing the time consumption; in view of this, the present invention provides a multi-beam forming method for phased array radar based on FPGA.

[0005] The technical solution adopted in this invention is a multi-beamforming method for phased array radar based on FPGA, comprising:

[0006] Step S1: Obtain w sets of initial phase codes for transmitting units, w sets of initial phase codes for receiving units, w sets of low sidelobe weights for receiving units, and n sets of beamforming codes sent by the control center, and store them in the specified address.

[0007] Step S2: In response to the received instruction, determine the transmit beam pointing code information, and use the corresponding initial phase code of the transmit unit and the beamforming code to determine the transmit control code of the final array antenna unit;

[0008] Step S3: Use the digital signal synthesizer in the FPGA to generate an intermediate frequency signal, and then convert it into a radio frequency signal through frequency conversion processing;

[0009] Step S4: In the array antenna unit, according to the transmission control code, the initial phase of the radio frequency signal is changed so that the radio frequency signal emitted by the array antenna unit forms a transmission beam with a certain direction in space.

[0010] Step S5: In response to the received instruction, determine the receiving beam pointing coding information, and use the receiving beam pointing coding information and the corresponding initial phase code of the receiving unit to determine the receiving control coding of the final array antenna unit. The corresponding low sidelobe weight of the receiving unit is determined as the receiving low sidelobe weight of the final array antenna unit.

[0011] Step S6: When receiving signals, the array antenna unit generates a received radio frequency signal using the received control coding and the received low sidelobe weights.

[0012] Step S7: The received radio frequency signal is converted into an intermediate frequency signal by frequency conversion processing, and the intermediate frequency signal is converted into a digital signal by AD sampling processing.

[0013] Step S8: In response to different directional information in the received instructions, multiple sets of feed phase gradients are generated, i.e., the weights of the receiver and the beam.

[0014] Step S9: Assign weights to different groups of receivers and beams in the digital signal to form multiple groups of receivers and beams.

[0015] In one embodiment, the transmitted beam pointing coding information is determined using center pointing angle information, the distance between the azimuth of the array units, and the distance between the elevation of the array units, wherein the center pointing angle information includes: azimuth angle and elevation angle.

[0016] In one implementation, the pointing information includes: azimuth angle and elevation angle.

[0017] Compared with the prior art, the present invention has at least the following advantages:

[0018] The FPGA-based phased array radar multi-beamforming method provided by this invention, based on the sequential scanning method of wave positions, utilizes the wide beam capability of the FPGA to achieve a wider airspace coverage per wave position and less time consumption within the same spatial domain. Attached Figure Description

[0019] Figure 1 This is a flowchart of a phased array radar multibeamforming method based on FPGA according to an embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram of the antenna layout according to an embodiment of the present invention;

[0021] Figure 3 is a transmission pattern of the array antenna according to an embodiment of the present invention, wherein Figure 3a This is the transmission pattern of a wide-beam array antenna. Figure 3b This is the transmission pattern of a narrow beam array antenna;

[0022] Figure 4 is a flowchart of the control code calculation according to an embodiment of the present invention, wherein... Figure 4a Here is a flowchart of the transmit control code calculation process. Figure 4b Flowchart for receiving control coding calculation;

[0023] Figure 5 This is a flowchart of the receiving multi-beam calculation according to an embodiment of the present invention. Detailed Implementation

[0024] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments.

[0025] In the accompanying drawings, the thickness, size, and shape of the objects have been slightly exaggerated for ease of illustration. The drawings are for illustrative purposes only and are not drawn to scale.

[0026] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising," when used in this specification, indicate the presence of the stated features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or combinations thereof. Furthermore, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire listed feature, not individual elements in the list. Additionally, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to an example or illustration.

[0027] As used herein, the terms “basically,” “approximately,” and similar terms are used as terms of approximation rather than terms of degree, and are intended to describe inherent biases in measured or calculated values ​​that will be recognized by those skilled in the art.

[0028] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms (e.g., those defined in common dictionaries) shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formal sense unless expressly so specified herein.

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] The steps described in the specification and the flowcharts in the accompanying drawings of this invention are not necessarily to be strictly followed according to the step numbers; the execution order of the steps can be changed. Furthermore, certain steps can be omitted, multiple steps can be combined into one step, and / or one step can be broken down into multiple steps.

[0031] The first embodiment of the present invention provides a multi-beamforming method for phased array radar based on FPGA, such as... Figure 1 As shown, the specific steps include the following:

[0032] Step S1: Obtain w sets of initial phase codes for transmitting units, w sets of initial phase codes for receiving units, w sets of low sidelobe weights for receiving units, and n sets of beamforming codes sent by the control center, and store them in the specified address.

[0033] Step S2: In response to the received instruction, determine the transmit beam pointing code information, and use the corresponding initial phase code of the transmit unit and the beamforming code to determine the transmit control code of the final array antenna unit;

[0034] Step S3: Use the digital signal synthesizer in the FPGA to generate an intermediate frequency signal, and then convert it into a radio frequency signal through frequency conversion processing;

[0035] Step S4: In the array antenna unit, according to the transmission control code, the initial phase of the radio frequency signal is changed so that the radio frequency signal emitted by the array antenna unit forms a transmission beam with a certain direction in space.

[0036] Step S5: In response to the received instruction, determine the receiving beam pointing coding information, and use the receiving beam pointing coding information and the corresponding initial phase code of the receiving unit to determine the receiving control coding of the final array antenna unit. The corresponding low sidelobe weight of the receiving unit is determined as the receiving low sidelobe weight of the final array antenna unit.

[0037] Step S6: When receiving signals, the array antenna unit generates a received radio frequency signal using the received control coding and the received low sidelobe weights.

[0038] Step S7: The received radio frequency signal is converted into an intermediate frequency signal by frequency conversion processing, and the intermediate frequency signal is converted into a digital signal by AD sampling processing.

[0039] Step S8: In response to different directional information in the received instructions, multiple sets of feed phase gradients are generated, i.e., the weights of the receiver and the beam.

[0040] Step S9: Assign weights to different groups of receivers and beams in the digital signal to form multiple groups of receivers and beams.

[0041] The second embodiment of the present invention is an application example corresponding to the first embodiment, combined with... Figures 2 to 5 The methods provided in this example specifically include:

[0042] like Figure 2 As shown in the figure, an array radar antenna is designed.

[0043] Step 1: When the device is first powered on, receive the initial phase codes of the w groups of transmitting units sent by the control center. Initial phase code of group w receiving unit Low sidelobe weighting of group w receiving units (Amp) r ) and n sets of beamforming codes (φ), which are stored in the specified address.

[0044] Step 2: As shown in Figure 4(a), according to the received instructions, which include azimuth, elevation, operating frequency, and start-of-calculation enable information, the center pointing angle information (azimuth: az0; elevation: el0) is obtained. The calculation formula (1) is as follows:

[0045]

[0046] Where, d x It is the distance between the orientations of the array elements, d y λ is the pitch distance between array units, and λ is the wavelength of the electromagnetic wave.

[0047] The beam pointing code information (α, β) is calculated, and the calculated transmit beam pointing code information is added to the initial phase code of the corresponding transmit unit in step 1. And beamforming code (φ), forming the transmit control code (grad) of the final array antenna element. t The broadened beam is shown in Figure 3(a), and the unbroadened beam is shown in Figure 3(b).

[0048] Step 3: An intermediate frequency (IF) signal is generated using the digital signal synthesizer (DDS) in the FPGA, and then converted into a radio frequency (RF) signal through frequency conversion. In the array antenna unit, the transmit control code (grad) is applied according to the steps in Step 2. t This changes the initial phase of the radio frequency signal, causing the radio frequency signal emitted by the array antenna element to form a directional transmission beam (S) in space. t ).

[0049]

[0050] Step 4: Analyze the information of the center pointing angle (azimuth: az0; elevation: el0). The calculation formula (3) is as follows:

[0051]

[0052] Where, d x It is the distance between the orientations of the array elements, d y λ is the pitch distance between array units, and λ is the wavelength of the electromagnetic wave.

[0053] The beam pointing code information (α, β) is calculated, and then the calculated beam pointing code information is added to the initial phase code of the corresponding transmitting unit in step 1. The receive control coding (grad) that forms the final array antenna element r The low sidelobe weight (Amp) of the receiving unit corresponding to step 1. r This refers to the received low sidelobe weights (Amp) of the final array antenna elements. r ).

[0054] Step 5: When receiving signals, the array antenna unit utilizes the receive control code and low sidelobe weights generated in Step 4. Upon receiving an RF signal, it performs frequency conversion to generate an intermediate frequency signal, which is then converted into a digital signal (S) using AD sampling. r Since there is only one set of array antenna elements, it will be referred to as common aperture in the following description.

[0055] Step 6: As shown in Figure 4(b), based on the received instructions, which include azimuth, elevation, operating frequency, and enable information for starting calculations, the different pointing information contained therein (azimuth: az0; elevation: el0; azimuth: az0) is used. n Pitch angle: el n This generates multiple sets of feed phase gradients, i.e., the receiver and beam weights W. n n is an integer, n≥1.

[0056] α0=Dx*sin(az0)*cos(el0) / λ

[0057] β0=Dy*sin(el0) / λ (4)

[0058] W0=(α0+β0)*2^16

[0059] α n =Dx*sin(az) n )*cos(el n ) / λ

[0060] β n =Dy*sin(el n ) / λ (5)

[0061] W n =(α n +β n )*2^16

[0062] Among them, D x D is the distance between the positions of the subarrays. y λ is the distance between the elevation and subarrays, and λ is the wavelength of the electromagnetic wave.

[0063] Step 7: As Figure 5 As shown, for the digital signal (s) in step 5 r In step 6, weights W are assigned to different groups of receivers and beams. n Multiple sets of receivers and beams are formed. n .

[0064] beam0 = W0 * s r (6)

[0065] beam n =W n *s r (7)

[0066] Assuming a scanned airspace of 30°, a non-widened beamwidth of 1.2°, and a widened beamwidth of 8°, without considering airspace overlap, scanning the entire airspace with a non-widened beam requires 25 scans, while scanning with a widened beam requires only 4 (rounded) scans. The widened beam scanning efficiency is 6 times that of the non-widened beam scanning, significantly improving the scanning efficiency of the array radar.

[0067] In summary, compared with the prior art, this embodiment has at least the following advantages:

[0068] 1) Compared with traditional multi-beam scanning, which scans sequentially according to the wave position, this invention utilizes its wide beam capability to cover a wider area of ​​the airspace with a single wave position and consumes less time in the same airspace.

[0069] 2) Compared with the method of receiving multiple beams simultaneously with different apertures, the present invention has a higher angular resolution due to the use of a common aperture, and will not suffer from loss of angular accuracy due to aperture segmentation.

[0070] 3) This invention broadens the transmitted waveform, thus covering a wider spatial domain and improving scanning efficiency.

[0071] Through the description of specific embodiments, a more in-depth and specific understanding should be gained of the technical means and effects adopted by the present invention to achieve the intended purpose. However, the accompanying drawings are only provided for reference and illustration and are not intended to limit the present invention.

Claims

1. A multi-beamforming method for phased array radar based on FPGA, characterized in that, include: Step S1: Obtain w sets of initial phase codes for transmitting units, w sets of initial phase codes for receiving units, w sets of low sidelobe weights for receiving units, and n sets of beamforming codes sent by the control center, and store them in the specified address. Step S2: In response to the received instruction, determine the transmit beam pointing code information, and use the corresponding initial phase code of the transmit unit and the beamforming code to determine the transmit control code of the final array antenna unit; Step S3: Use the digital signal synthesizer in the FPGA to generate an intermediate frequency signal, and then convert it into a radio frequency signal through frequency conversion processing; Step S4: In the array antenna unit, according to the transmission control code, the initial phase of the radio frequency signal is changed so that the radio frequency signal emitted by the array antenna unit forms a transmission beam with a certain direction in space. Step S5: In response to the received instruction, determine the receiving beam pointing coding information, and use the receiving beam pointing coding information and the corresponding initial phase code of the receiving unit to determine the receiving control coding of the final array antenna unit. The corresponding low sidelobe weight of the receiving unit is determined as the receiving low sidelobe weight of the final array antenna unit. Step S6: When receiving signals, the array antenna unit generates a received radio frequency signal using the received control coding and the received low sidelobe weights. Step S7: The received radio frequency signal is converted into an intermediate frequency signal by frequency conversion processing, and the intermediate frequency signal is converted into a digital signal by AD sampling processing. Step S8: In response to different directional information in the received instructions, multiple sets of feed phase gradients are generated, i.e., the weights of the receiver and the beam. Step S9: Assign weights to different groups of receivers and beams in the digital signal to form multiple groups of receivers and beams.

2. The FPGA-based phased array radar multi-beamforming method according to claim 1, characterized in that, The transmitted beam pointing coding information is determined using the center pointing angle information, the distance between the azimuth of the array units, and the distance between the elevation of the array units. The center pointing angle information includes the azimuth angle and the elevation angle.

3. The FPGA-based phased array radar multi-beamforming method according to claim 1, characterized in that, The directional information includes: azimuth angle and elevation angle.

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