An Adaptive Threshold Generation Method for Radar Signals and a Computer Readable Storage Medium

Abstract

A method for generating an adaptive threshold of radar signals provided by the present invention includes, when generating a threshold, assigning the lower limit of the system-set threshold received as the current threshold value; opening a time window with a number of points M and counting the M-point time window, including: counting every M points as a counting period, and within one counting period, recording the instantaneous amplitude values of a 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, then increasing the current threshold based on the current threshold; if the instantaneous amplitude values of the majority of points within the time window exceed the current threshold, when 1.25 times the average noise level exceeds the current threshold, increasing the current threshold based on the current threshold; when 1.25 times the average noise level is lower than the current threshold, decreasing the current threshold. The present invention also provides a computer-readable storage medium for implementing a method for generating an adaptive threshold of radar signals.

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] A wideband channelized digital receiver is an important part of a modern radar electronic reconnaissance system, 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 those 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 sensitivity of the receiver 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 that the digital receiver measures the current time-frequency characteristics based on the initial threshold, and hands over 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 the size of the noise floor, and then feeds back the new threshold to the wideband digital receiver. The externally bound real-time threshold is a feedback system. Although it 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, with complex design and low efficiency.

[0005] Therefore, it is necessary to design an adaptive threshold generation method, which can reduce the cooperation of the coprocessor, and at the same time, when measuring the time-frequency characteristics of the signal, the threshold can be adaptively adjusted according to the change of the application scenario. 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, the threshold value can be adaptively adjusted according to the change of 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 method for generating an adaptive threshold of radar signals provided by a technical solution of the present invention includes receiving the upper and lower values of the system-set threshold. The adaptive threshold value does not exceed the upper and lower values of the system-set threshold, and when generating the threshold, the received lower limit value of the system-set threshold 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, and within one counting period, recording the instantaneous amplitude values of most points within the time window; if the instantaneous amplitude values of most points within the time window do not exceed the current threshold value, the current threshold value is increased on the basis of the current threshold value; if the instantaneous amplitude values of most points within the time window exceed the current threshold value, when 1.25 times the average noise floor level exceeds the current threshold value, the current threshold value is increased on the basis of the current threshold value; when 1.25 times the average noise floor level is lower than the current threshold value, the current threshold value is decreased on the basis of the current threshold value. Compared with the prior art, the present invention can calculate the current threshold meeting the requirements based on the measured instantaneous amplitude data, the current threshold, and the upper and lower limits of the set threshold, without the cooperation of the processor, with a more concise design and reduced area overhead of the device.

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

[0011] When the current threshold value is increased, if the new threshold value after the increase exceeds the upper limit value of the set threshold, the upper limit value of the set threshold is used as the new threshold value; otherwise, the new threshold value after the increase is continued to be used; when the current threshold is decreased, if the new threshold value after the decrease is greater than the lower limit value of the set threshold, the new threshold value after the decrease is continued to be used; if the new threshold value after the decrease is less than the lower limit value of the set threshold, the lower limit value of the set threshold is used as the new threshold value.

[0012] When the new threshold value after the decrease exceeds 1.25 times the average noise floor level, the current threshold value is decreased, otherwise no decrease operation is performed.

[0013] Within one counting period, if the instantaneous amplitude of M / 2 - 2M / 3 points accumulatively exceeds the current threshold value, then the instantaneous amplitude values of most points within the time window exceed the current threshold; otherwise, the instantaneous amplitude values of most points within the time window do not exceed the current threshold.

[0014] Within one counting period, if the instantaneous amplitude of M / 2 - 2M / 3 points accumulatively 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 the current threshold value is 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 average value of the amplitude values is calculated. The average 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 a 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 performs threshold adjustment, 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 scheme 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, meeting the sensitivity requirements 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 Embodiments

[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

[0029] 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. Open a time window with M points and count the M-point time window. The counting includes: counting every M points as a counting cycle. Within one counting cycle, 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, the current threshold value is increased on the basis of 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 floor level exceeds the current threshold value, the current threshold value is increased on the basis of the current threshold value. When 1.25 times the average noise floor level is lower than the current threshold value, the current threshold value is decreased on the basis of the current threshold value. Embodiment 1 can calculate the current threshold value 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.

[0030] Combined with the accompanying drawings, the implementation process of the inventive concept of the present invention will be explained in detail below.

[0031] See Figure 1 , a method for generating an adaptive threshold for radar signals provided by the present invention includes the following steps:

[0032] 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.

[0033] 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.

[0034] 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 received lower limit value of the threshold bound by the system is assigned as the current threshold value.

[0035] 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 a narrow pulse signal, the selection range of the number of points M within the time window covers the entire pulse signal. In the case of a wide pulse signal, 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.

[0036] 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 value 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.

[0037] Step S3-2: Record the instantaneous amplitude values of most points within the time window within one counting period, and compare the selected instantaneous amplitude values of most points with the current threshold value. Specifically, within one counting period, if at least M / 2 - 2M / 3 points' instantaneous amplitude exceeds the current threshold value, 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.

[0038] The comparison of the instantaneous amplitude values of most points here with the current threshold value 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 system environment signal is active, and there may be more valid signals or the noise suddenly increases, and adjustments need to be made according to the situation.

[0039] Step S3-3: Within one counting period, if M / 2 - 2M / 3 points' instantaneous amplitude exceeds the current threshold value, a flag signal is generated starting from the point where the instantaneous amplitude exceeds the current threshold value. 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 value and dynamically adjust the current threshold value. Within the non-effective signal time of the envelope signal, do not perform the dynamic adjustment calculation of the threshold value.

[0040] Step S4: Based on the counting result, the current threshold value, and the upper and lower limits of the threshold value set in the system, adjust the current threshold value.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] The current threshold being lower than 1.25 times the average noise floor level means that the current threshold value is too low and the current threshold value needs to be increased to prevent noise from being misjudged as a signal.

[0045] 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.

[0046] 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.

[0047] 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 value 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. Under the high main processing clock of the conventional radar signal processing method, the delay 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, meeting the sensitivity requirements while not increasing the false alarm rate.

[0048] Embodiment 2

[0049] 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.

[0050] 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.

[0051] 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 in this technical field, without departing from the principle of the present invention, several improvements and modifications can still 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. An adaptive threshold generation method for radar signals, characterized in that The adaptive threshold generation method includes receiving the upper and lower values of the system-set threshold. The adaptive threshold value does not exceed the upper and lower values of the system-set threshold, and when generating the threshold, the received lower limit value of the system-set threshold is assigned as the current threshold value; Open a time window with M points and count the M-point time window. The counting includes: Each M points is a counting period. Within one counting period, record the instantaneous amplitude values of most points within the time window; Within one counting period, accumulate the instantaneous amplitude values of M / 2 - 2M / 3 points as the instantaneous amplitude values of most points; If the instantaneous amplitude values of most points within the time window do not exceed the current threshold value, the current threshold value is increased on the basis of the current threshold value; If the instantaneous amplitude values of most points within the time window exceed the current threshold value, when 1.25 times the average noise floor level exceeds the current threshold value, the current threshold value is increased on the basis of the current threshold value; when 1.25 times the average noise floor level is lower than the current threshold value, the current threshold value is decreased on the basis of the current threshold value; Within one counting period, accumulate the amplitude values of the points whose first M / 8 - M / 4 instantaneous amplitude values are less than the current threshold value, and calculate the average value of the amplitude values. The average value is the average noise floor level.

2. The method for generating an adaptive threshold of a radar signal according to claim 1, wherein When increasing the current threshold value, increase the current threshold value by 20% - 30% as the new threshold value after the increase; When decreasing the current threshold value, decrease the current threshold value by 10% - 15% as the new threshold value after the decrease.

3. A method for generating an adaptive threshold of radar signals 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 value of the set threshold, use the upper limit value of the set threshold as the new threshold value; otherwise, continue to use the new threshold value after the increase; When the current threshold value is decreased, if the new threshold value after the decrease is greater than the lower limit value of the set threshold, continue to use the new threshold value after the decrease; if the new threshold value after the decrease is less than the lower limit value of the set threshold, then use the lower limit value of the set threshold as the new threshold value.

4. A method for generating an adaptive threshold of a radar signal according to claim 3, characterized in that When the new threshold value after the decrease exceeds 1.25 times the average noise floor level, decrease the current threshold value; otherwise, do not perform the decrease operation.

5. A method for generating an adaptive threshold of radar signals according to claim 1, characterized in that, Within one counting period, if the instantaneous amplitude of M / 2 - 2M / 3 points accumulatively exceeds the current threshold value, a flag signal is generated starting from the point where the instantaneous amplitude exceeds the current threshold value.

6. A method for generating an adaptive threshold of a radar signal according to claim 5, wherein The generated flag signal is the calculated envelope signal. When the calculated envelope signal is valid, calculate the current threshold value and dynamically adjust the current threshold value.

7. A method for generating an adaptive threshold of radar signals according to claim 1, characterized in that 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.

8. A method for generating an adaptive threshold of a radar signal according to claim 1, characterized in that, The number of points M within the time window is selected according to the period and sampling frequency of the signal. Under narrow pulse signals, the selection range of the number of points M within the time window covers the entire pulse signal; Under 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.

9. A computer-readable storage medium, characterized in that, Program code is stored in the computer-readable storage medium, and the program code is called by a processor to execute the radar signal adaptive threshold generation method according to any one of claims 1-8.

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