An interference direction finding method for a phased array radar

Abstract

The present invention relates to the field of radar signal processing, and particularly to an interference direction finding method for a phased array radar. The present invention includes five main steps. Step 1: Obtain the maximum value of the amplitude mean of the echoes in the clean area among all the beams of the main channel. Step 2: Obtain the maximum value of the amplitude mean of the echoes in the clean area among all the beams of the auxiliary channel. Step 3: Establish an amplitude map of the echoes in the clean area of the main channel. Step 4: Establish an amplitude map of the echoes in the clean area of the auxiliary channel. Step 5: Give the interference flag and interference amplitude of each azimuth unit by comparing the amplitude maps of the echoes in the clean area of the main channel and the auxiliary channel. The present invention improves the search probability for interference and achieves an angular resolution of one beam width.

Description

Technical Field

[0001] The present invention relates to the field of radar signal processing, and particularly to an interference direction finding method for a phased array radar. Background Art

[0002] With the increasingly deteriorating battlefield electromagnetic confrontation environment, higher requirements are put forward for the anti-jamming performance of radars. As a key technology for radar interference reconnaissance, the interference direction finding technology can assist in sorting and identifying radiation source signals, and at the same time can give threat warnings and indicate threats; it is a prerequisite for radars to implement targeted anti-jamming means in actual combat environments. Precise interference direction finding makes it possible for radars to take different processing measures in the interference sector and the non-interference sector to balance the contradiction between the anti-jamming effect and the target detection loss.

[0003] The traditional interference direction finding method is single-beam search direction finding, with a narrow instantaneous detection range and unable to solve the contradiction between the search probability and the angular resolution.

[0004] Therefore, an interference direction finding method for a phased array radar is needed, which uses the multi-beam information formed after DBF to meet the requirements of the current radar system for the interference direction finding search probability and the angular resolution. Summary of the Invention

[0005] Aiming at the deficiencies of the traditional single-beam interference direction finding method, the present invention provides an interference direction finding method for a phased array radar, which can utilize the multi-beam information formed after DBF of radar echoes. If any beam in the multi-beams detects interference, subsequent interference discrimination will be carried out to improve the search probability for interference; and the angular resolution of 1 beam width is achieved through the division of azimuth units.

[0006] The technical solution of the present invention is: an interference direction finding method for a phased array radar, characterized by including the following steps:

[0007] Step 1, obtain the maximum value max_m of the amplitude mean of the clean area echoes in all beams of the main channel;

[0008] Step 2, obtain the maximum value max_f of the amplitude mean of the clean area echoes in all beams of the auxiliary channel;

[0009] Step 3, establish an amplitude map of the clean area echoes of the main channel. The specific process is as follows: accumulate max_m of each radar echo when the azimuth position coding map_az is the same. When map_az changes, divide the accumulated result of max_m by the number of accumulations to obtain the average value, and store the result avg_m in the amplitude map of the clean area echoes of the main channel. The storage position is the azimuth unit before the change of map_az;

[0010] Step 4: Establish the echo amplitude map of the auxiliary channel cleaning area. The specific process is as follows: Accumulate the max_f of each radar echo when map_az is the same. When map_az changes, divide the accumulated result of max_f by the number of accumulations to obtain the average value, and store the result avg_f in the echo amplitude map of the auxiliary channel cleaning area. The storage location is the azimuth cell before the change of map_az.

[0011] Step 5: Determine the interference flag and interference amplitude of each azimuth cell by comparing the echo amplitude maps of the main channel and the auxiliary channel cleaning area. The specific steps are as follows:

[0012] Step 5.1: After the echo amplitude maps of the main and auxiliary channels before the change of each map_az in Step 3 and Step 4 are stored, compare the echo amplitude map avg_m of the main channel and the echo amplitude map avg_f of the auxiliary channel at the same azimuth before the change of map_az. When avg_f > (noise + th_jam), go to Step 5.2; otherwise, there is no interference in this azimuth cell, and the subsequent steps are terminated.

[0013] Where noise is the logarithmic value of the radar echo noise amplitude when the radar turns off the transmitter and only turns on the receiver; th_jam is the passive interference detection threshold.

[0014] Step 5.2: When the difference between the echo amplitude map of the main channel and the echo amplitude map of the auxiliary channel (avg_m - avg_f) > th_mf, there is interference in this azimuth, and the interference intensity is jam_db = (avg_m - noise), where th_mf is the active interference detection threshold.

[0015] According to the interference direction finding method of a phased array radar as described above, it is characterized in that: The cleaning area is the long-distance section in the radar echo information.

[0016] According to the interference direction finding method of a phased array radar as described above, it is characterized in that: The calculation process of the amplitude mean value of the echo in the cleaning area of all beams in the main channel is as follows: Average the logarithmic values of the amplitudes of multiple echoes in the cleaning area of the main channel beam to obtain the amplitude mean value of the echo in the cleaning area of the main channel beam; Use the same method to obtain the amplitude mean values of the echoes in the cleaning areas of other main channel beams; Select the maximum value and record it as max_m.

[0017] According to the interference direction finding method of a phased array radar as described above, it is characterized in that: The calculation process of the amplitude mean value of the echo in the cleaning area of all beams in the auxiliary channel is as follows: Average the logarithmic values of the amplitudes of multiple echoes in the cleaning area of the auxiliary channel beam to obtain the amplitude mean value of the echo in the cleaning area of the auxiliary channel beam; Use the same method to obtain the amplitude mean values of the echoes in the cleaning areas of other auxiliary channel beams; Select the maximum value and record it as max_f.

[0018] According to the interference direction finding method of a phased array radar as described above, it is characterized in that: the total number of azimuth codes for one scan circle is 8192, with values ranging from 0 to 8191. The real-time azimuth code AZ of the radar is divided by 8 and rounded down to obtain the azimuth position code map_az.

[0019] According to the interference direction finding method of a phased array radar as described above, it is characterized in that: the value of th_jam is 6.

[0020] According to the interference direction finding method of a phased array radar as described above, it is characterized in that: the value of th_mf is 20.

[0021] The beneficial effects of the present invention are as follows: 1. The interference direction is updated in real time according to the radar scan cycle per circle. 2. By comprehensively processing the multi-beam echo information, the interference direction finding search probability is improved, and the missed detection and false alarm are reduced. 3. Different angular resolutions can be achieved by adjusting the azimuth unit size of the clean area echo amplitude map, and the minimum azimuth unit angle can be set to 1 beam width. Description of the Drawings

[0022] Figure 1 It is a schematic diagram of the implementation process of an interference direction finding method for a phased array radar. Detailed Embodiments

[0023] The following elaborates on the embodiments of the present invention in conjunction with the drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making the protection scope of the present invention more clearly defined.

[0024] The embodiment of the present invention provides an interference direction finding method for a phased array radar, which can be applied to the field of interference direction finding in radar signal processing.

[0025] Please refer to Figure 1 , an interference direction finding method for a phased array radar includes the following steps:

[0026] In this embodiment, the number of main channel beams of the radar is 8, the number of auxiliary channel beams is 3, the number of echo range cells of each channel of the radar is 4000, the clean area is selected as range cells 3501 - 4000 (a total of 500 range cells), and the beam width is 0.38 degrees;

[0027] We generally consider the short-distance segment in the radar echo information as the clutter area, where the target and clutter energy are strong, and the composition of the echo is complex, which is not conducive to estimating the echo environment when the radar is free of interference. On the contrary, the long-distance segment in the radar echo information (generally 500 range cells inward from the maximum detection distance of the radar) is considered as the clean area, where the target and clutter echo energy are weak and suitable for estimating the echo environment when the radar is free of interference.

[0028] Step 1: Obtain the maximum value max_m of the amplitude mean of the clean area echoes in all beams of the main channel.

[0029] The specific steps are as follows:

[0030] Average the 500 logarithmic values of the echo amplitudes in the clean area of beam 1 in the main channel (range cells 3501 - 4000, not elaborated below) to obtain the amplitude mean of the clean area echoes of beam 1 in the main channel, denoted as M1; use the same method to obtain the amplitude means of the clean area echoes of the other 7 beams in the main channel, denoted as M2, M3, M4, M5, M6, M7, M8 in sequence; select the maximum value among M1 - M8 and denote it as max_m.

[0031] The number of beams in the main channel is based on the number of beams formed after DBF of the phased array radar (in this embodiment, 8 beams are formed after DBF of the radar echo). Since the multiple beams formed after DBF of the phased array radar generally point to different angular spaces in the vertical direction, using the multi - beam information simultaneously can comprehensively evaluate the interference conditions in different altitude airspaces and improve the search probability for interference.

[0032] This step utilizes the multi - beam information of the radar echo. Any beam that receives interference information will be subject to interference discrimination in subsequent processing steps, which improves the search probability for interference compared to single - beam search.

[0033] Step 2: Obtain the maximum value max_f of the amplitude mean of the clean area echoes in all beams of the auxiliary channel.

[0034] The specific steps are as follows:

[0035] Average the 500 logarithmic values of the echo amplitudes in the clean area of beam 1 in the auxiliary channel to obtain the amplitude mean of the clean area echoes of beam 1 in the auxiliary channel, denoted as F1; use the same method to obtain the amplitude means of the clean area echoes of the other 2 beams in the auxiliary channel, denoted as F2, F3 in sequence; select the maximum value among F1 - F3 and denote it as max_f.

[0036] The number of auxiliary channels is based on the number of auxiliary antennas of the radar actually using this method. Generally, there are as many auxiliary channels as there are auxiliary antennas, and at least 1 auxiliary channel is required to obtain the information of interference entering from the auxiliary channel, which is convenient for comparison and judgment with the main channel information in subsequent steps.

[0037] Step 3: Establish the amplitude map of the clean area echoes in the main channel. The specific steps are as follows:

[0038] In this embodiment, the total number of azimuth codes for one full scan of the radar antenna is 8192, with values ranging from 0 to 8191. Divide the real-time azimuth code AZ of the radar by 8 and round down to obtain the azimuth position code map_az, with a value range of 0 to 1023.

[0039] The meaning of the above operation is as follows: The echo amplitude map is divided into 1024 azimuth units in the azimuth direction. Each unit contains data of 8 azimuth codes, which is equivalent to 0.35 degrees.

[0040] As the radar scans, accumulate the max_m of each radar echo when map_az is the same. When map_az changes, divide the accumulated result of max_m by the number of accumulations to obtain the average, and store the result avg_m in the echo amplitude map of the main channel cleaning area. The storage position is the azimuth unit before the change of map_az. Through the division of azimuth units in this step, the size of the azimuth unit in the cleaning area echo amplitude map is adjusted to meet different angular resolution requirements. The minimum azimuth unit angle can be set to 1 beam width.

[0041] Step 4: Establish the echo amplitude map of the auxiliary channel cleaning area. The specific steps are as follows:

[0042] As the radar scans, accumulate the max_f of each radar echo when map_az is the same. When map_az changes, divide the accumulated result of max_f by the number of accumulations to obtain the average, and store the result avg_f in the echo amplitude map of the auxiliary channel cleaning area. The storage position is the azimuth unit before the change of map_az.

[0043] Step 5: By comparing the echo amplitude maps of the main channel and the auxiliary channel cleaning areas, based on the passive interference detection threshold and the active interference detection threshold, give the interference flag and interference amplitude of each azimuth unit. The specific steps are as follows:

[0044] Step 5.1: After the echo amplitude maps of the main and auxiliary channels before the change of each map_az in Step 3 and Step 4 are stored, compare the echo amplitude map avg_m of the main channel and the echo amplitude map avg_f of the auxiliary channel at the same azimuth before the change of map_az. When avg_f > (noise + th_jam), proceed to Step 5.2; otherwise, it means there is no interference in this azimuth unit. Set the azimuth interference flag to "0" and terminate the subsequent steps.

[0045] Where noise is the logarithmic value of the radar echo noise amplitude when the radar transmitter is off and only the receiver is on. This value can be considered a fixed value for the same radar at a fixed position and only needs to be statistically obtained once after each change of the position; th_jam is the passive interference detection threshold, generally taking a value of 6.

[0046] Step 5.2: When the difference between the echo amplitude map of the main channel and that of the auxiliary channel (avg_m - avg_f) > th_mf, it indicates that there is interference in this azimuth. Set the azimuth interference flag to "1", and the interference intensity is jam_db = (avg_m - noise).

[0047] Among them, th_mf is the active interference detection threshold, and generally takes a value of 20. We believe that there is active interference in this azimuth only when the echo amplitude in the clean area of the main channel is more than 20 dB higher than that in the clean area of the auxiliary channel.

[0048] Through Step 5, the interference direction can be updated in real time according to each circle scanning period of the radar.

[0049] So far, this method can obtain the interference flag and interference intensity at the azimuth unit before the change of map_az after each change of map_az; after one circle of radar scanning, the interference direction map and interference intensity of the full azimuth can be obtained in real time.

[0050] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. All equivalent structural or equivalent process transformations made by using the content of the specification and drawings of the present invention, or directly or indirectly applied to other related technical fields, are equally included in the patent protection scope of the present invention.

Claims

1. A method for interference direction finding of a phased array radar, characterized in that: It includes the following steps: Step 1: Obtain the maximum value max_m of the amplitude mean of the echo in the clean area among all the beams in the main channel; Step 2: Obtain the maximum value max_f of the amplitude mean of the echo in the clean area among all the beams in the auxiliary channel; Step 3: Establish the amplitude map of the echo in the clean area of the main channel. The specific process is as follows: Accumulate max_m of each radar echo when the azimuth position coding map_az is the same. When map_az changes, divide the accumulated result of max_m by the number of accumulations to obtain the average, and store the result avg_m in the amplitude map of the echo in the clean area of the main channel. The storage position is the azimuth unit before the change of map_az; Step 4: Establish the amplitude map of the echo in the clean area of the auxiliary channel. The specific process is as follows: Accumulate max_f of each radar echo when map_az is the same. When map_az changes, divide the accumulated result of max_f by the number of accumulations to obtain the average, and store the result avg_f in the amplitude map of the echo in the clean area of the auxiliary channel. The storage position is the azimuth unit before the change of map_az; Step 5: Determine the interference flag and interference amplitude of each azimuth unit by comparing the amplitude maps of the echo in the clean area of the main channel and the auxiliary channel. The specific steps are as follows: Step 5.1: After the amplitude maps of the main and auxiliary echoes before the change of each map_az in Step 3 and Step 4 are stored, compare the amplitude map avg_m of the main channel and the amplitude map avg_f of the auxiliary channel at the same azimuth before the change of map_az. The comparison between avg_m and avg_f is after the change of map_az, but the values used for comparison are obtained before the change of map_az. When avg_f > (noise + th_jam), perform Step 5.2; otherwise, there is no interference in this azimuth unit, and terminate the subsequent steps; where noise is the logarithm of the radar echo noise amplitude when the radar only turns on the receiver without turning on the transmitter; th_jam is the passive interference detection threshold; Step 5.2: When the difference between the amplitude map of the echo in the main channel and the amplitude map of the echo in the auxiliary channel (avg_m - avg_f) > th_mf, there is interference in this azimuth, and the interference intensity is jam_db = (avg_m - noise), where th_mf is the active interference detection threshold.

2. The interference direction finding method of a phased array radar according to claim 1, characterized in that: The clean area is the long-distance section in the radar echo information.

3. The interference direction finding method of a phased array radar according to claim 1, characterized in that: The calculation process of the amplitude mean of the echo in the clean area among all the beams in the main channel is as follows: Average the multiple logarithm values of the echo amplitudes in the clean area of the main channel beams to obtain the amplitude mean of the echo in the clean area of the main channel beams; use the same method to obtain the amplitude means of the echo in the clean area of other main channel beams; select the maximum value and record it as max_m.

4. A method for interference direction finding of a phased array radar according to claim 1, characterized in that: The calculation process of the amplitude mean of the echo in the clean area among all the beams in the auxiliary channel is as follows: Average the multiple logarithm values of the echo amplitudes in the clean area of the auxiliary channel beams to obtain the amplitude mean of the echo in the clean area of the auxiliary channel beams, and use the same method to obtain the amplitude means of the echo in the clean area of other auxiliary channel beams; Select the maximum value and record it as max_f.

5. A method for interference direction finding of a phased array radar according to claim 1, characterized in that: The total number of azimuth codes for one scan is 8192, with values ranging from 0 to 8191. Divide the real-time azimuth code AZ of the radar by 8 and round down to obtain the azimuth position code map_az.

6. A method for interference direction finding of a phased array radar according to any one of claims 1 to 5, characterized in that: The value of th_jam is 6.

7. A method for interference direction finding of a phased array radar according to any one of claims 1 to 5, characterized in that: The value of th_mf is 20.

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