Radar signal adaptive threshold generation method and computer readable storage medium

Abstract

The invention provides a radar signal adaptive threshold generation method, which comprises the following steps of: when a threshold is generated, assigning a lower limit of a received system binding threshold as a current threshold value; opening a time window with the point number of M, and counting the time window with the point number of M: counting every M points as a counting period, and recording instantaneous amplitude values of a plurality of points in the time window in one counting period; if the instantaneous amplitude values of the majority of points in the time window do not exceed the current threshold, increasing the current threshold on the basis of the current threshold; if the instantaneous amplitude values of the majority of points in the time window exceed the current threshold and 1.25 times of the average level of the noise floor exceeds the current threshold, the current threshold is increased on the basis of the current threshold; and when 1.25 times of the average level of the noise floor is lower than the current threshold, the current threshold is lowered. The invention further provides a computer readable storage medium which is used for realizing the radar signal adaptive threshold generation method.

Description

Technical Field

[0001] The present invention belongs to the technical field of radar target detection, and particularly relates to a method for generating an adaptive threshold for radar signals and a computer-readable storage medium. Background Art

[0002] The wideband channelized digital receiver is an important part of modern radar electronic reconnaissance systems, which requires rapid and high-precision measurement of time-frequency characteristics such as target frequency information, amplitude information, and pulse width information within a large bandwidth range.

[0003] The measurement of time-frequency characteristics is closely related to the signal threshold of the system. Only signals exceeding the threshold are considered real targets. Selecting an appropriate threshold directly determines the performance of the receiver. If the threshold is too high, the receiver sensitivity will decrease; if the threshold is too low, the false alarm probability will increase.

[0004] In conventional wideband channelized digital receivers, there are usually two types of measurement thresholds: fixed thresholds and externally bound real-time thresholds. The fixed threshold is determined by a large number of actual tests in various electromagnetic environments to determine the system threshold. This type of threshold is easy to use but not flexible. In some scenarios, if the electromagnetic environment around the receiver deteriorates and there is broadband electromagnetic interference within the frequency band resulting in an elevated noise floor, a large number of false targets will appear, leading to the annihilation of real targets. The externally bound real-time threshold is a feedback system where the digital receiver measures the current time-frequency characteristics based on the initial threshold, and then hands the time-frequency characteristic results to the subsequent processor for processing. The subsequent processor determines a new threshold based on the measured signal amplitude and noise floor size, and then feeds the new threshold back to the wideband digital receiver. Although the externally bound real-time threshold is an improvement over the fixed threshold, its real-time performance is poor, and the probabilities of missed alarms and false alarms are still relatively high. It requires the participation of the subsequent processor, and the design is complex and inefficient.

[0005] Therefore, it is necessary to design an adaptive threshold generation method that can reduce the cooperation of the coprocessor and, at the same time, can adaptively adjust the threshold according to changes in the application scenario when measuring the time-frequency characteristics of signals. Summary of the Invention

[0006] The present invention provides a method for generating an adaptive threshold for radar signals, which can be calculated based on the instantaneous amplitude data measured by the receiver channelization, the current threshold, and the upper and lower limits of the bound threshold, reducing the cooperative processing of the processor. At the same time, it can also adaptively adjust the threshold value according to changes in the application scenario.

[0007] The present invention also provides a computer-readable storage medium for implementing the steps in a method for generating an adaptive threshold for radar signals.

[0008] Other objects and advantages of the present invention can be further understood from the technical features disclosed in the present invention.

[0009] To achieve one or part or all of the above purposes or other purposes, a technical solution of the present invention provides a radar signal adaptive threshold generation method, the adaptive threshold generation method comprising: receiving the upper and lower values ​​of the system binding threshold, the adaptive threshold value does not exceed the upper and lower values ​​of the system binding threshold, and when the threshold is generated, assigning the received lower limit value of the system binding threshold as the current threshold value; opening a time window with M points, and counting the M-point time window, the counting includes: counting each M points as a counting cycle, and within a counting cycle, recording the instantaneous amplitude values ​​of most points in the time window; if the instantaneous amplitude values ​​of most points in the time window do not exceed the current threshold value, then the current threshold value is increased based on the current threshold value; if the instantaneous amplitude values ​​of most points in the time window exceed the current threshold value, when the average level of the noise floor exceeds the current threshold value by 1.25 times, the current threshold value is increased based on the current threshold value; when the average level of the noise floor is 1.25 times lower than the current threshold value, the current threshold value is lowered based on the current threshold value. Compared with the prior art, the present invention can calculate the threshold that meets the current requirements based on the measured instantaneous amplitude data, the current threshold and the upper and lower limits of the binding threshold, without the need for processor coordination, and has a simpler design, reducing the area overhead of the device.

[0010] When the current threshold is adjusted upward, the current threshold value increased by 20%-30% is used as the new threshold value after the increase; when the current threshold is adjusted downward, the current threshold value decreased by 10%-15% is used as the new threshold value after the decrease.

[0011] When the current threshold value is adjusted upward, if the new threshold value after the increase exceeds the upper limit value of the binding threshold, the upper limit value of the binding threshold will be used as the new threshold value, otherwise, the new threshold value after the increase will continue to be used; when the current threshold is adjusted downward, if the new threshold value after the decrease is greater than the lower limit value of the binding threshold, the new threshold value after the decrease will continue to be used; if the new threshold value after the decrease is less than the lower limit value of the binding threshold, the lower limit value of the binding threshold will be used as the new threshold value.

[0012] When the new threshold value after the downward adjustment exceeds 1.25 times the average level of the noise floor, the current threshold value is downward adjusted; otherwise, the downward adjustment operation is not performed.

[0013] In a counting cycle, if the instantaneous amplitude of the accumulated M / 2-2M / 3 points exceeds the current threshold value, the instantaneous amplitude values ​​of most points in the time window exceed the current threshold; otherwise, the instantaneous amplitude values ​​of most points in the time window do not exceed the current threshold.

[0014] In one counting cycle, if the instantaneous amplitude of the accumulated M / 2-2M / 3 points exceeds the current threshold value, a flag signal is generated starting from the point where the instantaneous amplitude exceeds the current threshold value.

[0015] The generated flag signal is the calculated envelope signal. When the calculated envelope signal is valid, the current threshold value is calculated and dynamically adjusted.

[0016] Within one counting period, the amplitude values of the points where the first M / 8 - M / 4 instantaneous amplitude values are less than the current threshold value are accumulated, and the mean value of the amplitude values is calculated. The mean value is the average noise floor level.

[0017] The signal with the largest instantaneous amplitude is selected from all channels, and the measured instantaneous amplitude information is sent to the threshold measurement module. The threshold measurement module adaptively generates the threshold based on the instantaneous amplitude information.

[0018] The number of points M within the time window is selected based on the period of the signal and the sampling frequency. In the case of narrow pulse signals, the selected range of the number of points M within the time window covers the entire pulse signal; in the case of wide pulse signals, the selected range of the number of points M within the time window is from 1 / 8 to 1 / 4 of the start part of the pulse signal.

[0019] A computer-readable storage medium provided by another technical solution of the present invention is characterized in that program codes are stored in the computer-readable storage medium, and the program codes are called by a processor to execute the radar signal adaptive threshold generation method described above.

[0020] Compared with the prior art, the beneficial effects of the present invention mainly include: 1. When the present invention adjusts the threshold, it is calculated based on the instantaneous amplitude data of the channelized digital receiver channelization test, the current threshold value, and the bound upper and lower threshold values, without the cooperation of a coprocessor, which simplifies the structural design. At the same time, the existing method of using an external processor to assist in determining the threshold requires statistical information of multiple measurement pulses, and the threshold update has a delay of hundreds of milliseconds due to the transmission bandwidth limitation.

[0021] 2. When the threshold of the present invention is adjusted, when the instantaneous amplitude values of most points exceed the current threshold value, by comparing the current threshold value with 1.25 times the average noise floor level and adjusting the current threshold according to the comparison result, it can be ensured that the threshold changes with the change of the average noise floor level. More precisely, the threshold fluctuates up and down around 1.25 times the average noise floor level. Specifically, when 1.25 times the noise floor is higher than the current threshold, the solution used in the present invention continuously provides a new threshold value to approach 1.25 times the noise floor level without exceeding the upper limit value of the bound threshold value. When 1.25 times the noise floor level is lower than the current threshold, the threshold starts to be gradually reduced to approach 1.25 times the noise floor level. In the conventional radar signal processing method, the delay at a high main processing clock is in the order of microseconds, meeting the requirements of most application scenarios. At the same time, it is ensured that the adjusted threshold is 25% higher than the average noise floor level, satisfying the sensitivity requirement while not increasing the false alarm rate.

[0022] 3. When adjusting the current threshold in the present invention, the length of the time window selected, that is, the number of points M within the time window, can be selected according to the application scenario. Therefore, the time window can be adjusted accordingly with the change of the application scenario, so that the adaptive threshold value meets the requirements of different application scenarios.

[0023] 4. The adaptive threshold generation method of the present invention is implemented in a channelized digital receiver. Existing channelized digital receivers are all implemented based on FPGA. The present invention can reduce the occupation of FPGA logic resources and reduce the area overhead of the device.

[0024] To make the above and other purposes, features and advantages of the present invention more obvious and understandable, the following specifically enumerates preferred embodiments and, in conjunction with the accompanying drawings, makes a detailed description as follows. Brief Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions in the specific embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] Figure 1 It is a flowchart for implementing the radar signal adaptive threshold generation method of the present invention. Detailed Embodiment

[0027] Regarding the foregoing and other technical contents, features and effects of the present invention, they will be clearly presented in the following detailed description of a preferred embodiment in conjunction with the reference drawings. The directional terms mentioned in the following embodiments, such as: up, down, left, right, front or back, etc., are only with reference to the directions of the attached drawings. Therefore, the directional terms used are for illustration and not for limiting the present invention.

[0028] Embodiment 1 Embodiment 1 provides a method for generating an adaptive threshold for radar signals. The adaptive threshold generation method includes receiving the upper and lower values of the threshold bound by the system. The adaptive threshold value does not exceed the upper and lower limit values of the threshold bound by the system. When generating the threshold, the received lower limit value of the threshold bound by the system is assigned as the current threshold value; opening a time window with a number of points M and counting the M-point time window. The counting includes: counting every M points as a counting period. Within one counting period, record the instantaneous amplitude values of the majority of points within the time window; if the instantaneous amplitude values of the majority of points within the time window do not exceed the current threshold value, then increase the current threshold value based on the current threshold value; if the instantaneous amplitude values of the majority of points within the time window exceed the current threshold value, when 1.25 times the average noise level exceeds the current threshold value, increase the current threshold value based on the current threshold; when 1.25 times the average noise level is lower than the current threshold value, decrease the current threshold value based on the current threshold value. Embodiment 1 can calculate the current threshold that meets the requirements based on the measured instantaneous amplitude data, the current threshold, and the upper and lower limits of the bound threshold, without the cooperation of the processor, with a more concise design and reduced area overhead of the device.

[0029] Combined with the accompanying drawings, the implementation process of the inventive concept of the present invention will be explained in detail below.

[0030] See Figure 1 , a method for generating an adaptive threshold for radar signals provided by the present invention includes the following steps: Step S1: Select the signal with the largest instantaneous amplitude among all channels and send the measured instantaneous amplitude information to the threshold measurement module. The threshold measurement module adaptively generates the threshold based on the instantaneous amplitude information.

[0031] In Embodiment 1, the pulse amplitude information with the largest instantaneous amplitude is selected as the basis for generating the adaptive threshold because there are multiple channels in the system. Different channels may receive signals from different sources or with different intensities simultaneously. The signal with the largest instantaneous amplitude can capture the strongest signal among all channels, avoiding missed detection of key signals. At the same time, taking the maximum amplitude as the benchmark avoids the complexity and resource consumption brought by independent processing of multiple channels. Step S2: Receive the upper and lower limit values of the threshold bound by the system. The adaptive threshold value does not exceed the upper and lower limit values of the threshold bound by the system, and the lower limit value of the received threshold bound by the system is assigned as the current threshold value.

[0032] Step S3: Open a time window with M points. Count every M points as a counting period and count the M-point time window. The selection of the number of points M within the time window is based on the period of the signal and the sampling frequency. In the case of narrow pulse signals, the selection range of the number of points M within the time window covers the entire pulse signal. In the case of wide pulse signals, the selection range of the number of points M within the time window is from 1 / 8 to 1 / 4 of the start part of the pulse signal.

[0033] Step S3-1: Within one counting period, at least accumulate the amplitude values of the points whose instantaneous amplitude values are less than the current threshold among the first 8 / M - M / 4 points, and calculate the average value of the amplitude values. The calculated average value is the average noise floor level of the current signal.

[0034] Step S3-2: Record the instantaneous amplitude values of most points within the time window within one counting period, and compare the instantaneous amplitude values of the selected most points with the current threshold. Specifically, within one counting period, if at least M / 2 - 2M / 3 points' instantaneous amplitude exceeds the current threshold, it is considered that the instantaneous amplitude values of most points within the time window exceed the current threshold; otherwise, it is considered that the instantaneous amplitude values of most points within the time window do not exceed the current threshold.

[0035] The comparison of the instantaneous amplitude values of most points here with the current threshold is to distinguish the system environment. If the instantaneous amplitude values of most points do not exceed the threshold, it is considered that the current system environment is relatively quiet, mainly noise, and the signal is weak. At this time, the threshold can be increased to avoid being too sensitive and reduce false detection of noise. If the instantaneous amplitude values of most points exceed the threshold, it is considered that the signal in the system environment is active, and there may be more valid signals or the noise suddenly increases, and adjustments need to be made according to the situation.

[0036] Step S3-3: Within one counting period, if M / 2 - 2M / 3 points' instantaneous amplitude exceeds the current threshold, a flag signal is generated starting from the point where the instantaneous amplitude exceeds the current threshold. The flag signal generated here is the calculated envelope signal (the calculated envelope signal refers to the contour curve that reflects the change of the signal amplitude over time extracted from the original signal through mathematical or signal processing methods, capturing the outer edge of the signal amplitude). Within the effective signal time of the calculated envelope signal, calculate the current threshold and dynamically adjust the current threshold. Within the non-envelope signal's effective signal time, no dynamic adjustment calculation of the threshold is performed.

[0037] Step S4: Based on the counting result, the current threshold, and the upper and lower limits of the threshold set in the system, adjust the current threshold.

[0038] Step S4-1: Compare the instantaneous amplitude values of multiple points with the current threshold value. If the instantaneous amplitude values of multiple points do not exceed the current threshold, it indicates that the current environment of the system is relatively quiet. Then increase the threshold. Based on the current threshold value, increase it by 20% - 30% of the current threshold value as the new adjusted threshold value. If the newly adjusted threshold value calculated in Step S4-1 is smaller than the upper limit of the system-set threshold, use the newly adjusted threshold value; if the newly adjusted threshold value is larger than the upper limit of the system-set threshold, use the upper limit of the system-set threshold as the new threshold value.

[0039] Step S4-2: If the instantaneous amplitude of multiple points exceeds the current threshold, at this time, it is necessary to compare the current threshold with 1.25 times the average noise floor level and then make adjustments. Here, it is necessary to compare with 1.25 times the average noise floor level, with an appropriate increase on the average noise floor level as a margin. Comparing the current threshold with 1.25 times the average noise floor level can help evaluate whether the system threshold deviates from the reasonable range. Specifically, it includes the following steps.

[0040] Step S4-2-1: If 1.25 times the average noise floor level exceeds the current threshold value, increase the threshold. Based on the current threshold value, increase it by 20% - 30% of the current threshold value as the new adjusted threshold value. If the newly adjusted threshold value is smaller than the upper limit value of the system-set threshold, use the newly adjusted threshold value; if the newly adjusted threshold value is larger than the upper limit value of the system-set threshold, use the upper limit value of the system-set threshold as the new threshold value.

[0041] The current threshold being lower than 1.25 times the average noise floor level means that the current threshold value is too low, and it is necessary to increase the current threshold value to prevent noise from being misjudged as a signal.

[0042] Step S4-2-2: If 1.25 times the average noise floor level does not exceed the current threshold value, when adjusting the current threshold downwards, reduce it by 10% - 15% of the current threshold value as the new adjusted threshold value. When the newly adjusted threshold value after reduction exceeds 1.25 times the average noise floor level, adjust the current threshold value downwards, otherwise do not perform the downward adjustment operation. When the current threshold is adjusted downwards, if the newly adjusted threshold value after reduction is greater than the lower limit of the set threshold, continue to use the newly adjusted threshold value after reduction; if the newly adjusted threshold value after reduction is smaller than the lower limit value of the set threshold, use the lower limit value of the set threshold as the new threshold value.

[0043] Based on Step S4, the current threshold value can be dynamically adjusted adaptively, so that the adaptive threshold value meets the requirements of the measurement environment.

[0044] The present invention compares the current threshold with 1.25 times the average noise floor level and adjusts the current threshold according to the comparison result, which can ensure that the threshold changes with the change of the average noise floor level. More precisely, the threshold fluctuates around 1.25 times the average noise floor level. Specifically, when 1.25 times the noise floor is higher than the current threshold, the solution used in the present invention continuously provides a new threshold to approach the 1.25 times noise floor level without exceeding the upper limit value of the binding threshold value. When 1.25 times the noise floor level is lower than the current threshold, the threshold starts to be gradually reduced to approach the 1.25 times noise floor level. In the conventional radar signal processing method, the delay is in the order of microseconds under a high main processing clock, meeting the requirements of most application scenarios. At the same time, it is ensured that the adjusted threshold is 25% higher than the average noise floor level, meeting the sensitivity requirements while not increasing the false alarm rate.

[0045] Embodiment 2 Embodiment 2 provides a computer-readable storage medium, in which program code is stored, and the program code is called by a processor to execute the specific steps of the radar signal adaptive threshold generation method described in Embodiment 1.

[0046] The computer-readable storage medium provided by Embodiment 2 is called by the stored program code to execute the specific steps of the radar signal adaptive threshold generation method in Embodiment 1, and has the advantage of high execution efficiency.

[0047] The above has introduced in detail a radar signal adaptive threshold generation method and a computer-readable storage medium provided by the present invention. Specific examples are used in this article to elaborate on the structure and working principle of the present invention. The description of the above embodiments is only used to help understand the method and core idea of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A radar signal adaptive threshold generation method, characterized in that: The adaptive threshold generation method includes receiving upper and lower values ​​of the system binding threshold, the adaptive threshold value does not exceed the upper and lower values ​​of the system binding threshold, and when the threshold is generated, assigning the received lower limit value of the system binding threshold as the current threshold value; Open a time window with M points and count the M-point time window. The count includes: Every M points counted is a counting cycle. In one counting cycle, the instantaneous amplitude values ​​of most points in the time window are recorded; If the instantaneous amplitude values ​​of most points in the time window do not exceed the current threshold value, the current threshold value is adjusted upward based on the current threshold value; If the instantaneous amplitude values ​​of most points in the time window exceed the current threshold value, when the average level of the noise floor exceeds the current threshold value by 1.25 times, the current threshold value will be adjusted upward based on the current threshold value; when the average level of the noise floor is lower than the current threshold value by 1.25 times, the current threshold value will be adjusted downward based on the current threshold value.

2. A radar signal adaptive threshold generation method according to claim 1, characterized in that: When the current threshold is adjusted upward, the current threshold value increased by 20%-30% is used as the new threshold value after the increase; When the current threshold is lowered, the current threshold value is lowered by 10%-15% as the new threshold value after the lowering.

3. A radar signal adaptive threshold generation method according to claim 2, characterized in that: When the current threshold value is increased, if the new threshold value after the increase exceeds the upper limit of the binding threshold, the upper limit of the binding threshold is used as the new threshold value, otherwise, the new threshold value after the increase continues to be used; When the current threshold is lowered, if the new threshold value after the reduction is greater than the lower limit of the binding threshold, the new threshold value after the reduction is continued to be used; if the new threshold value after the reduction is less than the lower limit of the binding threshold, the lower limit of the binding threshold is used as the new threshold value.

4. A radar signal adaptive threshold generation method according to claim 3, characterized in that: When the new threshold value after the downward adjustment exceeds 1.25 times the average level of the noise floor, the current threshold value is downward adjusted; otherwise, the downward adjustment operation is not performed.

5. The radar signal adaptive threshold generation method according to claim 1, characterized in that: In a counting cycle, if the instantaneous amplitude of the accumulated M / 2-2M / 3 points exceeds the current threshold value, then the instantaneous amplitude values ​​of most points in the time window exceed the current threshold; Otherwise, the instantaneous amplitude values ​​of most points in the time window do not exceed the current threshold.

6. A radar signal adaptive threshold generation method according to claim 5, characterized in that: In one counting cycle, if the instantaneous amplitude of the accumulated M / 2-2M / 3 points exceeds the current threshold value, a flag signal is generated starting from the point where the instantaneous amplitude exceeds the current threshold value.

7. A radar signal adaptive threshold generation method according to claim 6, characterized in that: The generated flag signal is the calculated envelope signal. When the calculated envelope signal is valid, the current threshold value is calculated and dynamically adjusted.

8. The radar signal adaptive threshold generation method according to claim 1, characterized in that: In one counting cycle, the amplitude values ​​of the points whose instantaneous amplitude values ​​are smaller than the current threshold value in the first M / 8-M / 4 are accumulated, and the average of the amplitude values ​​is calculated, and the average is the average level of the noise floor.

9. The radar signal adaptive threshold generation method according to claim 1, characterized in that: A signal with the largest instantaneous amplitude is selected from all channels, and the measured instantaneous amplitude information is sent to a threshold measurement module, and the threshold measurement module performs adaptive generation of a threshold according to the instantaneous amplitude information.

10. The radar signal adaptive threshold generation method according to claim 1, characterized in that: The number of points M in the time window is selected based on the period and sampling frequency of the signal. Under a narrow pulse signal, the selection range of the number of points M in the time window covers the entire pulse signal; Under a wide pulse signal, the selection range of the number of points M in the time window is 1 / 8 to 1 / 4 of the beginning part of the pulse signal.

11. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores program code, and the program code is called by a processor to execute the radar signal adaptive threshold generation method according to any one of claims 1 to 10.

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