CN112285665A

CN112285665A - Signal detection method and device, millimeter wave radar module, equipment and medium

Info

Publication number: CN112285665A
Application number: CN202011098029.XA
Authority: CN
Inventors: 陈有生
Original assignee: Guangzhou Xaircraft Technology Co Ltd
Current assignee: Guangzhou Xaircraft Technology Co Ltd
Priority date: 2020-10-14
Filing date: 2020-10-14
Publication date: 2021-01-29
Anticipated expiration: 2040-10-14
Also published as: CN112285665B

Abstract

The invention discloses a signal detection method, a signal detection device, a millimeter wave radar module, equipment and a medium, wherein the method comprises the following steps: acquiring a Fourier transformed signal matched with an intermediate frequency measurement signal detected by a millimeter wave radar module, wherein the Fourier transformed signal comprises a plurality of signal points; clustering each signal point in the Fourier transformed signal according to a preset cluster number, and obtaining a first detection threshold corresponding to the Fourier transformed signal according to at least one cluster center obtained after clustering; calculating to obtain second detection threshold values respectively corresponding to signal points in the Fourier transformed signal by adopting a preset algorithm; and determining a target signal point and a noise signal point in the Fourier transformed signal according to the first detection threshold and the second detection threshold. The technical scheme of the embodiment of the invention can improve the accuracy of the detection result of the millimeter wave radar module on the target signal point.

Description

Signal detection method and device, millimeter wave radar module, equipment and medium

Technical Field

The embodiment of the invention relates to a data signal processing technology, in particular to a signal detection method, a signal detection device, a millimeter wave radar module, equipment and a medium.

Background

The millimeter wave radar module is a radar working in millimeter wave band detection, has the advantages of strong anti-interference capability, small size and good concealment, and is widely applied to the field of unmanned aerial vehicle measurement. The distance principle of the millimeter wave radar module for detecting the target is shown in fig. 1: the synthesizer transmits the modulated electromagnetic wave to a radar transmitting antenna (TX antenna), the radar transmitting antenna sends the electromagnetic wave, a target object receives the electromagnetic wave and then reflects the electromagnetic wave to a receiving antenna (RX antenna), and an Intermediate Frequency (IF) measurement signal is obtained after a signal reflected by the target object and a transmitting signal of the transmitting antenna pass through a mixer; after the Analog Digital Converter (ADC) collects the intermediate frequency measurement signal, the ADC performs Analog-to-Digital conversion to obtain a converted intermediate frequency measurement signal (ADC signal); after the ADC signal is subjected to digital signal processing, such as Fast Fourier Transform (FFT), a processed signal (FFT signal) can be obtained; and then, detecting the FFT signal to obtain the frequency corresponding to the maximum amplitude of the FFT signal, and calculating the distance from the target object according to the frequency, wherein a set numerical relation exists between the distance and the frequency.

The conventional detection method usually adopts a Constant False Alarm Rate (CFAR) in the radar field, but the method has the problems of low sensitivity and low accuracy, and particularly, under the premise of existence of self-coupling signals and noise signals, the CFAR algorithm can falsely detect unnecessary signals almost every time.

Disclosure of Invention

The embodiment of the invention provides a signal detection method, a signal detection device, a millimeter wave radar module, equipment and a medium, which can improve the accuracy of a detection result of a target signal point by the millimeter wave radar module.

In a first aspect, an embodiment of the present invention provides a method for detecting a millimeter wave radar signal, including:

acquiring a Fourier transformed signal matched with an intermediate frequency measurement signal detected by a millimeter wave radar module, wherein the Fourier transformed signal comprises a plurality of signal points;

clustering each signal point in the Fourier transformed signal according to a preset cluster number, and obtaining a first detection threshold corresponding to the Fourier transformed signal according to at least one cluster center obtained after clustering;

calculating to obtain second detection threshold values respectively corresponding to the signal points in the Fourier transformed signal by adopting a preset algorithm;

and determining a target signal point and a noise signal point in the Fourier transformed signal according to the first detection threshold and the second detection threshold.

Optionally, the clustering each signal point in the fourier transformed signal according to a preset cluster number, and obtaining a first detection threshold corresponding to the fourier transformed signal according to at least one cluster center obtained after clustering, includes:

initializing cluster centers respectively corresponding to the cluster clusters according to the preset cluster number;

taking the initialized cluster center as a starting point, carrying out multiple clustering processing on each signal point in the Fourier transformed signal, and carrying out cyclic iteration to obtain stable cluster centers respectively corresponding to each cluster;

and determining the first detection threshold value according to the stable cluster center with the maximum signal value in each stable cluster center.

Optionally, initializing cluster centers respectively corresponding to the cluster clusters according to a preset cluster number, including:

selecting a maximum signal value from signal values corresponding to all signal points included in the Fourier transformed signal;

acquiring preset proportional coefficients respectively corresponding to the clustering clusters according to the preset cluster number;

and taking the product of the maximum signal value and each preset proportionality coefficient as a cluster center corresponding to each cluster.

Optionally, determining the first detection threshold according to a largest stable cluster center in the cluster centers includes:

if the maximum stable cluster center is smaller than or equal to a first threshold constant, taking the first threshold constant as a first detection threshold;

if the maximum stable cluster center is larger than a first threshold constant and smaller than a second threshold constant, taking the maximum stable cluster center as a first detection threshold;

if the maximum stable cluster center is larger than or equal to a second threshold constant, taking the second threshold constant as a first detection threshold;

wherein the first threshold constant is less than the second threshold constant.

Optionally, determining a target signal point in the fourier transformed signal according to the first detection threshold and the second detection threshold, includes:

sequentially acquiring a signal point in the Fourier transformed signal as a current processing signal point;

if the signal value of the currently processed signal point is greater than or equal to the first detection threshold and greater than or equal to a second detection threshold matched with the currently processed signal point, taking the currently processed signal point as a target signal point;

if the signal value of the currently processed signal point is smaller than any one of the first detection threshold value and the second detection threshold value, taking the currently processed signal point as a noise signal point;

and returning to execute the operation of sequentially acquiring one signal point in the Fourier transformed signals as the current processing signal point until the processing of all the signal points in the Fourier transformed signals is completed.

Optionally, obtaining a signal after fourier transform matched with the intermediate frequency measurement signal detected by the millimeter wave radar module includes:

acquiring a digital signal sequence matched with an intermediate frequency measurement signal detected by a millimeter wave radar module;

and carrying out fast Fourier transform on the digital signal sequence to obtain a Fourier transformed signal.

Optionally, before performing fast fourier transform on the digital signal sequence to obtain a fourier transformed signal, the method further includes:

dividing the digital signal sequence into a plurality of data packets, wherein each data packet comprises a plurality of digital signal items;

determining a noise data packet and a valid data packet in each data packet according to the fluctuation degree of each digital signal item in each data packet;

and replacing the digital signal items in the noise data packet according to the digital signal items in at least one effective data packet to obtain the digital signal sequence after interference removal.

Optionally, after obtaining the digital signal sequence after interference removal, the method further includes:

fitting the digital signal sequence after interference removal by adopting a polynomial fitting method to obtain fitting values respectively corresponding to all digital signal items in the digital signal sequence after interference removal;

and subtracting the corresponding fitting value from each digital signal item to obtain a direct-current-removed digital signal sequence corresponding to the interference-removed digital signal sequence.

Optionally, after determining a target signal point in the post-fourier-transform signal according to the first detection threshold and the second detection threshold, the method further includes:

and calculating the distance between the millimeter wave radar module and a target object according to the position of the target signal point in the signal after the Fourier transform.

In a second aspect, an embodiment of the present invention further provides a detection apparatus for a millimeter wave radar signal, where the apparatus includes:

the acquisition module is used for acquiring a Fourier transformed signal matched with the intermediate frequency measurement signal detected by the millimeter wave radar module, and the Fourier transformed signal comprises a plurality of signal points;

the first detection threshold calculation module is used for clustering signal points in the Fourier transformed signal according to a preset cluster number and obtaining a first detection threshold corresponding to the Fourier transformed signal according to at least one cluster center obtained after clustering;

the second detection threshold calculation module is used for calculating to obtain second detection thresholds respectively corresponding to the signal points in the Fourier transformed signal by adopting a preset algorithm;

and the determining module is used for determining a target signal point and a noise signal point in the Fourier transformed signal according to the first detection threshold and the second detection threshold.

In a third aspect, an embodiment of the present invention further provides a millimeter wave radar module, where the millimeter wave radar module includes:

the antenna module is used for sending electromagnetic wave signals to the surrounding environment and receiving echo signals matched with the electromagnetic wave signals;

the mixer is used for mixing the electromagnetic wave signal and the echo signal to obtain an intermediate frequency measurement signal;

the analog-to-digital converter is used for performing analog-to-digital conversion on the intermediate frequency measurement signal to obtain a digital signal sequence;

one or more processors; storage means for storing one or more programs; when the one or more programs are executed by the one or more processors, the one or more processors implement a method for detecting a millimeter wave radar signal according to any of the embodiments of the present invention.

In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium, where the storage medium stores a computer program, and the computer program, when executed by a processor, implements a method for detecting a millimeter wave radar signal according to any embodiment of the present invention.

In a fifth aspect, an embodiment of the present invention further provides a mobile device, where the millimeter wave radar module provided in any embodiment of the present invention is configured on the mobile device.

According to the technical scheme of the embodiment of the invention, the accuracy of the detection result of the millimeter wave radar module on the target signal point can be improved by acquiring the Fourier transformed signal matched with the intermediate frequency measurement signal detected by the millimeter wave radar module, clustering each signal point in the Fourier transformed signal according to the preset cluster number, obtaining the first detection threshold corresponding to the Fourier transformed signal according to at least one cluster center obtained after clustering, calculating the second detection threshold corresponding to each signal point in the Fourier transformed signal by adopting a preset algorithm, and determining the target signal point and the noise signal point in the Fourier transformed signal according to the first detection threshold and the second detection threshold.

Drawings

FIG. 1 is a schematic diagram of a millimeter wave radar module detecting a target distance;

FIG. 2 is a flowchart of a method for detecting a millimeter-wave radar signal according to a first embodiment of the present invention;

fig. 3a is a flowchart of a detection method of a millimeter wave radar signal according to a second embodiment of the present invention;

FIG. 3b is a diagram of a Fourier transformed signal in accordance with a second embodiment of the present invention;

FIG. 3c is a diagram illustrating a first detection threshold and a second detection threshold calculated from a Fourier transformed signal according to a second embodiment of the present invention;

fig. 4a is a flowchart of a detection method of a millimeter wave radar signal according to a third embodiment of the present invention;

fig. 4b is a schematic diagram of a digital signal sequence of the interfered if measurement signal matching in the third embodiment of the present invention;

fig. 4c is a schematic diagram of a digital signal sequence of the match of the intermediate frequency measurement signal after interference elimination in the third embodiment of the present invention;

fig. 5a is a flowchart of a detection method of a millimeter wave radar signal according to a fourth embodiment of the present invention;

FIG. 5b is a schematic diagram of a digital signal sequence without DC component removed according to a fourth embodiment of the present invention;

FIG. 5c is a schematic diagram of a prior art method after performing DC removal processing on a digital signal sequence and performing Fourier transform;

FIG. 5d is a diagram illustrating a digital signal sequence after being fitted in the fourth embodiment of the present invention;

fig. 5e is a schematic diagram of the digital signal sequence after dc component removal processing according to the fourth embodiment of the present invention;

fig. 5f is a schematic diagram of the dc-removed signal sequence after fourier transform according to the fourth embodiment of the present invention;

fig. 6 is a configuration diagram of a wave detection device of a millimeter wave radar signal in the fifth embodiment of the present invention;

fig. 7 is a schematic structural diagram of a millimeter wave radar module according to a sixth embodiment of the present invention;

fig. 8 is a schematic structural diagram of a mobile device in a seventh embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

Example one

Fig. 2 is a flowchart of a millimeter wave radar signal detection method according to an embodiment of the present invention, where this embodiment is applicable to a case of detecting a signal obtained by a millimeter wave radar module after fourier transform, and the method may be executed by a millimeter wave radar signal detection apparatus, which may be implemented by software and/or hardware, and may be generally integrated in the millimeter wave radar module, and specifically includes the following steps:

and 110, acquiring a Fourier transformed signal matched with the intermediate frequency measurement signal detected by the millimeter wave radar module, wherein the Fourier transformed signal comprises a plurality of signal points.

In this embodiment, the millimeter wave radar module is installed on a mobile device (such as an unmanned aerial vehicle, an unmanned vehicle, and an unmanned ship), and is used for measuring the distance between the mobile device and a target object. For example, in order to ensure smooth completion of plant protection operation, an agricultural plant protection unmanned aerial vehicle appearing in recent years needs to keep a constant distance from a plant to the unmanned aerial vehicle all the time, and the distance is calculated by a millimeter wave radar module.

In an implementation manner of the embodiment of the present invention, acquiring a post-fourier-transform signal matched with an intermediate-frequency measurement signal detected by a millimeter wave radar module includes: acquiring a digital signal sequence matched with an intermediate frequency measurement signal detected by a millimeter wave radar module; and carrying out fast Fourier transform on the digital signal sequence to obtain a Fourier transformed signal.

The intermediate frequency measurement signal is a signal obtained by mixing an electromagnetic wave signal sent by an antenna module in the millimeter wave radar module and a received echo signal through a mixer in the millimeter wave radar module; the digital signal sequence is a signal obtained after an intermediate frequency measurement signal is processed by an analog-to-digital converter in the millimeter wave radar module.

And 120, clustering each signal point in the Fourier transformed signal according to a preset cluster number, and obtaining a first detection threshold corresponding to the Fourier transformed signal according to at least one cluster center obtained after clustering.

In an implementation manner of the embodiment of the present invention, clustering each signal point in the fourier-transformed signal according to a preset cluster number, and obtaining a first detection threshold corresponding to the fourier-transformed signal according to at least one cluster center obtained after clustering, includes: initializing cluster centers respectively corresponding to the cluster clusters according to the preset cluster number; taking the initialized cluster center as a starting point, carrying out multiple clustering processing on each signal point in the Fourier transformed signal, and carrying out cyclic iteration to obtain stable cluster centers respectively corresponding to each cluster; and determining the first detection threshold value according to the stable cluster center with the maximum signal value in each stable cluster center.

Optionally, initializing cluster centers respectively corresponding to the cluster clusters according to a preset cluster number, including: selecting a maximum signal value from signal values corresponding to all signal points included in the Fourier transformed signal; acquiring preset proportional coefficients respectively corresponding to the clustering clusters according to the preset cluster number; and taking the product of the maximum signal value and each preset proportionality coefficient as a cluster center corresponding to each cluster.

In a specific embodiment, the largest signal value k may be selected from signal values corresponding to all signal points in the fourier-transformed signal, assuming that the preset number of clusters is 3, the cluster center corresponding to each cluster is initialized, and the cluster center corresponding to the first cluster is obtained as k₁The cluster center corresponding to the second cluster is k₂The cluster center corresponding to the third cluster is k₃Wherein each is initiatedClustered center k₁，k₂，k₃Is the product of the maximum signal value k and a number of different predetermined scaling factors, in particular k₁＝k*0.8，k₂＝k*0.4，k₃＝k*0；

Then calculating Euclidean distances between each signal point in the signals after Fourier transform and each initialized cluster center, taking the signal point with the shortest Euclidean distance from each initialized cluster center as a center reference point, and marking each center reference point to the cluster where the corresponding initialized cluster center is located; calculating the average value of the signal values of the centers of the initialized clusters and the corresponding center reference points, and replacing the centers of the initialized clusters with the average values; and repeating the steps until the center of each initialized cluster is unchanged, and taking the cluster center as a stable cluster center when the center of each initialized cluster is unchanged. In this embodiment, the preset cluster number and the preset scaling factor are set according to actual conditions, which is not limited in this embodiment.

After the stable cluster centers respectively corresponding to each cluster are obtained by the method, specifically, the stable cluster center with the largest signal value can be selected as the first detection threshold.

And step 130, calculating to obtain second detection threshold values respectively corresponding to the signal points in the Fourier transformed signal by adopting a preset algorithm.

In this embodiment, optionally, a constant false alarm detection algorithm may be used to estimate the background clutter power level of each signal point, and then the estimated value of the background clutter power level corresponding to each signal point is multiplied by a preset value to obtain a second detection threshold corresponding to each signal point.

And step 140, determining a target signal point and a noise signal point in the fourier transformed signal according to the first detection threshold and the second detection threshold.

In an implementation manner of the embodiment of the present invention, determining a target signal point in the post-fourier-transform signal according to the first detection threshold and the second detection threshold includes: sequentially acquiring a signal point in the Fourier transformed signal as a current processing signal point; if the signal value of the currently processed signal point is greater than or equal to the first detection threshold and greater than or equal to a second detection threshold matched with the currently processed signal point, taking the currently processed signal point as a target signal point; if the signal value of the currently processed signal point is smaller than any one of the first detection threshold value and the second detection threshold value, taking the currently processed signal point as a noise signal point; and returning to execute the operation of sequentially acquiring one signal point in the Fourier transformed signals as the current processing signal point until the processing of all the signal points in the Fourier transformed signals is completed.

In this embodiment, since the intermediate frequency measurement signal detected by the millimeter wave radar module is a time domain signal with a fixed frequency, after the intermediate frequency measurement signal is subjected to fast fourier transform, the obtained signal after fourier transform will have a signal with a very strong amplitude at a certain frequency point. In the existing constant false alarm detection algorithm, when a target signal point is determined, only the signal value of the signal point is usually compared with a second detection threshold, and when the signal value of the signal point is greater than the corresponding second detection threshold, the signal point is taken as the target signal point. In this embodiment, the signal value of the signal point is compared with the first detection threshold and the second detection threshold at the same time, and since the first detection threshold can reflect the clustering level of the signal point and is greater than the second detection thresholds corresponding to most signal points, the target signal point is determined in the post-fourier-transform signal according to the first detection threshold and the second detection threshold, and the accuracy of the detection result of the millimeter wave radar module on the target signal point can be improved.

Example two

In this embodiment, a specific implementation manner for determining the first detection threshold corresponding to the fourier transformed signal is provided on the basis of the foregoing embodiment, and the same or corresponding terms as those in the foregoing embodiment are explained, and this embodiment is not repeated again. Fig. 3a is a flowchart of a detection method for a millimeter wave radar signal according to a second embodiment of the present invention, in this embodiment, the technical solution of this embodiment may be combined with one or more methods in the solutions of the foregoing embodiments, as shown in fig. 3a, the method according to the second embodiment of the present invention may further include:

and step 210, acquiring a Fourier transformed signal matched with the intermediate frequency measurement signal detected by the millimeter wave radar module, wherein the Fourier transformed signal comprises a plurality of signal points.

Step 220, initializing cluster centers respectively corresponding to the cluster clusters according to the preset cluster number.

And step 230, taking the initialized cluster center as a starting point, performing clustering processing on each signal point in the Fourier transformed signal for multiple times, and performing loop iteration to obtain stable cluster centers respectively corresponding to each cluster.

And 240, determining a first detection threshold value according to the stable cluster center with the maximum signal value in each stable cluster center.

In one implementation manner of the embodiment of the present invention, determining the first detection threshold according to the stable cluster center with the largest signal value in each stable cluster center includes: if the center of the stable cluster with the maximum signal value is smaller than or equal to a first threshold constant, taking the first threshold constant as a first detection threshold value; if the stable cluster center with the maximum signal value is larger than the first threshold constant and smaller than the second threshold constant, taking the stable cluster center with the maximum signal value as a first detection threshold; if the center of the stable cluster with the maximum signal value is larger than or equal to a second threshold constant, taking the second threshold constant as a first detection threshold; wherein the first threshold constant is less than the second threshold constant.

When the center of the largest stable cluster is smaller than or equal to the first threshold constant, the first threshold constant is used as a first detection threshold value, so that the first detection threshold value can be prevented from being too small; when the center of the stable cluster with the largest signal value is larger than or equal to the second threshold constant, the second threshold constant is used as the first detection threshold value, the situation that the target signal point cannot be identified due to the fact that the first detection threshold value is too large can be avoided, and therefore the accuracy of the detection result of the millimeter wave radar module on the target signal point can be improved.

And step 250, calculating to obtain second detection threshold values respectively corresponding to the signal points in the Fourier transformed signal by adopting a preset algorithm.

And step 260, determining a target signal point and a noise signal point in the Fourier transformed signal according to the first detection threshold and the second detection threshold.

FIG. 3b is a diagram of a Fourier transformed signal obtained in the present embodiment; fig. 3c is a schematic diagram of the first detection threshold and the second detection threshold calculated for the post-fourier-transformed signal of fig. 3b, where the horizontal axis represents frequency and the vertical axis represents signal value. As shown in fig. 3c, curve 1 is the same fourier transformed signal as in fig. 3b, curve 2 is the calculated first detection threshold, and curve 3 is the calculated second detection threshold using the constant false alarm detection algorithm. It can be seen from fig. 3c that the abscissa of the first target signal point detected by the constant false alarm detection algorithm is about 20, the abscissa of the first target signal point detected by the first detection threshold in this embodiment is about 445, and the abscissa of the first target signal point detected by the first detection threshold in combination with the second detection threshold is about 447. Therefore, it can be shown that the detection method of the millimeter wave radar signal according to the embodiment can improve the detection performance of the constant false alarm detection algorithm, reduce the false detection rate of the constant false alarm detection algorithm, and as can be seen from fig. 3c, a large number of false detection results exist when the constant false alarm detection algorithm is used for detecting the target signal point in the first 400 signal points, and the position of the target signal point can be accurately detected after the clustering processing is added.

And 270, calculating the distance between the millimeter wave radar module and the target object according to the position of the target signal point in the signal after the Fourier transform.

In this step, as shown in fig. 3c, according to the position of the target signal point in the signal after fourier transform, the frequency corresponding to the target signal point may be obtained, and according to this frequency, the distance between the millimeter wave radar module and the target object may be calculated, where there is a set numerical relationship between the distance and the frequency.

The technical scheme of the embodiment of the invention comprises the steps of acquiring a Fourier transform signal matched with an intermediate frequency measurement signal obtained by detection of a millimeter wave radar module, initializing cluster centers respectively corresponding to each cluster according to a preset cluster number, carrying out multiple clustering processing on each signal point in the Fourier transform signal by taking the initialized cluster center as a starting point, circularly iterating to obtain stable cluster centers respectively corresponding to each cluster, determining a first detection threshold value according to the stable cluster center with the largest signal value in each stable cluster center, calculating by adopting a preset algorithm to obtain second detection threshold values respectively corresponding to each signal point in the Fourier transform signal, determining a target signal point and a noise signal point according to the first detection threshold value and the second detection threshold value, improving the accuracy of a detection result of the millimeter wave radar module on the target signal point and improving the detection performance of a constant false alarm detection algorithm, and the false detection rate of the constant false alarm detection algorithm is reduced.

EXAMPLE III

This embodiment is a further refinement of the above embodiment, and the same or corresponding terms as those of the above embodiment are explained, and this embodiment is not described again. Fig. 4a is a flowchart of a detection method for a millimeter wave radar signal according to a third embodiment of the present invention, in this embodiment, the technical solution of this embodiment may be combined with one or more methods in the solutions of the foregoing embodiments, as shown in fig. 4a, the method according to the third embodiment of the present invention may further include:

and 310, acquiring a digital signal sequence matched with the intermediate frequency measurement signal detected by the millimeter wave radar module.

Step 320, dividing the digital signal sequence into a plurality of data packets, wherein each data packet includes a plurality of digital signal items.

In this step, the digital signal sequence is composed of a plurality of digital signal points, and the digital signal sequence is divided into a plurality of data packets according to the output order of the analog-to-digital converter and a preset packet length, wherein the value of each digital signal point in each data packet is called a digital signal item, and the packet length of each data packet is the same. Assuming that the analog-to-digital converter outputs 440 digital signal points and the preset packet length is 10, the 10 digital signal points are grouped into 44 data packets, the 1 st digital signal point to the 10 th digital signal point are the first group, the 11 th digital signal point to the 20 th digital signal point are the second group, and so on. The packet length is preset according to actual conditions, which is not limited in this embodiment.

Step 330, determining a noise data packet and a valid data packet in each data packet according to the fluctuation degree of each digital signal item in each data packet.

In this embodiment, considering that the electromagnetic wave signal emitted by the millimeter wave radar module is a standard sinusoidal signal, which theoretically does not fluctuate to a large extent, if the fluctuation degree of a certain section of sinusoidal signal is large, it can be stated that a noise term is introduced into the section of sinusoidal signal. Namely: if the fluctuation degree of each digital signal item in the data packet is relatively large, the data packet can be determined as a noise data packet, and conversely, the data packet can be determined as a valid data packet. If the data packet is a valid data packet, it indicates that each digital signal item in the data packet is valid data required in the process of measuring the distance by the millimeter wave radar module.

In one implementation of the embodiment of the present invention, determining a noise data packet and a valid data packet in each data packet according to a fluctuation degree of each digital signal item in each data packet includes: respectively calculating extreme value differences between the maximum values in the groups and the minimum values in the groups in the data groups, and calculating average extreme value differences according to the extreme value differences of the data groups; and determining the noise data packet and the effective data packet in each data packet according to the numerical relation between the extreme value difference and the average extreme value difference of each data packet.

The maximum value in the group in the data grouping is the maximum value in each digital signal item, the minimum value in the group is the minimum value in each digital signal item, and the difference value between the maximum value in the group and the minimum value in the group is the extreme value difference. Assuming that the digital signal sequence is divided into 44 data packets in step 320, each data packet corresponds to an extreme value difference, there are 44 extreme value differences, and the average extreme value difference is obtained by averaging the 44 extreme value differences. Then judging whether each extreme value difference is larger than the product of the average extreme value difference and a set proportion coefficient; if so, determining the data packet corresponding to the extreme value difference as a noise data packet; if not, the data packet corresponding to the extreme value difference is determined as a valid data packet. The set proportionality coefficient is associated with the configuration parameters of the millimeter wave radar module and the model of the unmanned aerial vehicle to which the millimeter wave radar module is adapted, and is an adjustable constant, which may be 30, for example.

And 340, replacing the digital signal item in the noise data packet according to the digital signal item in at least one effective data packet to obtain a digital signal sequence after interference removal.

In one implementation of the embodiment of the present invention, replacing digital signal items in a noise data packet according to digital signal items in at least one valid data packet to obtain an interference-free signal sequence matching the digital signal sequence includes: acquiring a digital signal item in one valid data packet, such as acquiring a digital signal item of a valid data packet adjacent to the left or right of the noise data packet, and using the digital signal item in the valid data packet as replacement data in the noise data packet to replace the digital signal item in the noise data packet; or

Performing interpolation calculation according to the maximum value and the minimum value of the digital signal items in one effective data packet, for example, acquiring the maximum value and the minimum value of the digital signal items of the effective data packet adjacent to the left or the right of the noise data packet, and interpolating to obtain a plurality of interpolation signal items matched with the number of the digital signal items in the noise data packet; replacing digital signal terms in the associated noise data packet using the interpolated signal terms; or

Traversing each noise data packet, and respectively acquiring at least one effective data packet from the left side and the right side of each noise data packet; according to digital signal items in at least one effective data packet on the left side and the right side of each noise data packet and a preset interpolation algorithm, interpolating to obtain a plurality of interpolation signal items matched with the number of the digital signal items in the noise data packets; replacing digital signal terms in the associated noise data packet using the interpolated signal terms.

If a plurality of noise data packets are adjacent, the plurality of noise data packets can be combined into a new noise data packet, so that the plurality of noise data packets can be subjected to interference elimination processing together, and the processing efficiency is improved. If there are valid data packets on both the left and right sides of the noise data packet, interpolation operation may be performed on the last digital signal item in the left data packet of the noise data packet and the first digital signal item in the right data packet of the noise data packet according to a preset interpolation algorithm to obtain a plurality of interpolation signal items that match the number of digital signal items in the noise data packet, and then the digital signal items in the noise data packet may be replaced with the plurality of interpolation signal items. The preset interpolation algorithm may be a linear interpolation algorithm or a non-linear interpolation algorithm, which is not limited in this embodiment.

Therefore, by carrying out interpolation operation on the digital signal item in at least one effective data packet at the left side and the right side of the noise data packet and replacing the digital signal item in the noise data packet by the operated interpolation signal item, the digital signal item in the noise data packet can be close to the digital signal item in the effective data packet, thereby realizing the interference elimination of the signal.

In this embodiment, optionally, before replacing the digital signal item in the noise data packet according to the digital signal item in the at least one valid data packet, the method further includes: determining whether the noise data packet is a first data packet or a last data packet of the plurality of data packets; if yes, all digital signal items in the noise data packet currently processed are set as preset data values; if not, the digital signal item in the noise data packet is replaced according to the digital signal item in at least one effective data packet.

Wherein if the currently processed noise data packet does not have a left adjacent data packet, it may be determined that the noise data packet is a first data packet of the plurality of data packets; if the currently processed noise data packet does not have a right adjacent data packet, the noise data packet may be determined to be the last data packet of the plurality of data packets. If the noise data packet is the first data packet or the last data packet of the plurality of data packets, all of the digital signal items in the currently processed noise data packet are set to a preset data value.

Before the millimeter wave radar module processes (for example, fourier transform) the digital signal sequence, it is usually necessary to perform truncation processing on the digital signal sequence by using a window function, and digital signal items at the beginning and the end of the digital signal sequence have little influence on a processed result, so if there is no valid data packet adjacent to the left or valid data packet adjacent to the right in the currently processed noise data packet, all digital signal items in the currently processed noise data packet may be set to zero.

Fig. 4b is a schematic diagram of a digital signal sequence matched with the interfered intermediate frequency measurement signal in the embodiment, where the abscissa is the serial number of each digital signal point output by the analog-to-digital converter, and the ordinate is a digital signal item. As shown in fig. 4b, the digital signal sequence from the 350 th digital signal point to the 400 th digital signal point is severely interfered. The digital signal sequence in fig. 4b is processed according to the interference removing method of this embodiment, and fig. 4c is obtained, as shown in fig. 4c, each digital signal item in the digital signal sequence fluctuates around a stable constant value, and the fluctuation degree of each digital signal item is relatively small, so as to achieve the effect of removing interference from the intermediate frequency measurement signal in fig. 4 b.

And 350, performing fast Fourier transform on the digital signal sequence to obtain a Fourier transformed signal.

And 360, clustering each signal point in the Fourier transformed signal according to a preset cluster number, and obtaining a first detection threshold corresponding to the Fourier transformed signal according to at least one cluster center obtained after clustering.

And 370, calculating to obtain second detection threshold values respectively corresponding to the signal points in the signals after the Fourier transform by adopting a preset algorithm.

And 380, determining a target signal point and a noise signal point in the Fourier transformed signal according to the first detection threshold and the second detection threshold.

The technical scheme of the embodiment of the invention comprises the steps of grouping digital signal sequences matched with intermediate frequency measurement signals obtained by a millimeter wave radar module, determining noise data groups and effective data according to the fluctuation degree of each digital signal item in each data group, replacing the digital signal items in the noise data groups according to the digital signal items in at least one effective data group, carrying out fast Fourier transform on the replaced digital signal sequences, carrying out clustering processing on each signal point according to the preset cluster number, obtaining a first detection threshold value corresponding to signals after Fourier transform according to the cluster center calculated after clustering, obtaining second detection threshold values respectively corresponding to each signal point in the signals after Fourier transform by adopting a preset algorithm, and determining target signal points and noise signal points in the signals after Fourier transform according to the first detection threshold value and the second detection threshold values, the interference signals in the intermediate frequency measurement signals can be effectively eliminated, the accuracy of the millimeter wave radar module on the detection result of the target signal point is improved, the detection performance of the constant false alarm detection algorithm is improved, and the false detection rate of the constant false alarm detection algorithm is reduced.

Example four

This embodiment is a further refinement of the above embodiment, and the same or corresponding terms as those of the above embodiment are explained, and this embodiment is not described again. Fig. 5a is a flowchart of a detection method for a millimeter wave radar signal according to a fourth embodiment of the present invention, in this embodiment, the technical solution of this embodiment may be combined with one or more methods in the solutions of the foregoing embodiments, as shown in fig. 5a, the method according to the fourth embodiment of the present invention may further include:

step 401, a digital signal sequence matched with the intermediate frequency measurement signal detected by the millimeter wave radar module is obtained.

Step 402, dividing the digital signal sequence into a plurality of data packets, wherein the data packets comprise a plurality of digital signal items.

Step 403, determining a noise data packet and a valid data packet in each data packet according to the fluctuation degree of each digital signal item in each data packet.

And step 404, replacing the digital signal item in the noise data packet according to the digital signal item in at least one effective data packet to obtain a digital signal sequence after interference removal.

And 405, fitting the digital signal sequence after interference removal by adopting a polynomial fitting method to obtain fitting values respectively corresponding to all digital signal items in the digital signal sequence after interference removal.

The millimeter wave radar module usually needs to remove a direct current component in the digital signal sequence in the process of measuring the distance, if the direct current component exists in the digital signal sequence, a large low-frequency component easily exists in data obtained by performing fourier transform on the digital signal sequence by the millimeter wave radar module, and the low-frequency component can cover a real low-frequency signal. The existing method for removing the direct current component comprises the following steps: and subtracting the average value of the whole digital signal item from each digital signal item to obtain a direct current signal removing sequence. However, if the mean value of the whole digital signal item is not a straight line, the existing method has low-frequency interference data in the data after the direct current signal sequence is subjected to fourier transform.

Fig. 5b is a schematic diagram of a digital signal sequence without removing a dc component in this embodiment, fig. 5c is a schematic diagram of the digital signal sequence in fig. 5b after dc removal processing and fourier transform are performed by a conventional method, and an abscissa in fig. 5c represents a frequency and an ordinate represents a signal value. As can be seen from fig. 5c, there is low-frequency interference data in the data obtained by performing fourier transform on the dc-removed signal sequence in the conventional method.

This embodiment proposes an implementation in which each digital signal item is subtracted from the fitting value corresponding to each digital signal item to remove the dc component. In a specific embodiment, the fitting method of 5 th order polynomial may be used to fit the digital signal sequence, or a polyfit function may be called in Matrix Laboratory software (MATLAB) to obtain the fitting result of the interference-free signal sequence. As shown in fig. 5d, curve 1 is a digital signal sequence without removing the dc component, and curve 2 is a curve obtained by fitting the digital signal sequence without removing the dc component.

And 406, subtracting the corresponding fitting value from each digital signal item to obtain a direct-current-removed digital signal sequence corresponding to the interference-removed digital signal sequence.

As shown in fig. 5d, the dc-removed signal sequence, i.e. curve 3, can be obtained by subtracting curve 2 from curve 1.

And 407, performing fast Fourier transform on the digital signal sequence subjected to direct current removal to obtain a Fourier transformed signal.

Fig. 5e is a schematic diagram of fig. 5b after dc component removal, the curve in fig. 5e is the same as curve 3 in fig. 5d, and fig. 5f is a schematic diagram of fig. 5e after fourier transformation of the dc removed signal sequence. As can be seen from fig. 5f and 5c, the amplitude of the low frequency in fig. 5f is smaller than the amplitude of the following real signal, and the amplitude of the low frequency in fig. 5c is larger than the amplitude of the following real signal, so that it can be demonstrated that the method for removing the dc component proposed in this embodiment has better effect than the method for removing the dc component in the prior art.

And 408, clustering each signal point in the Fourier transformed signal according to a preset cluster number, and obtaining a first detection threshold corresponding to the Fourier transformed signal according to at least one cluster center obtained after clustering.

And 409, calculating to obtain second detection thresholds respectively corresponding to the signal points in the Fourier transformed signal by adopting a preset algorithm.

And step 410, determining a target signal point and a noise signal point in the Fourier transformed signal according to the first detection threshold and the second detection threshold.

According to the technical scheme of the embodiment of the invention, digital signal sequences matched with intermediate frequency measurement signals and detected by a millimeter wave radar module are grouped, and noise data groups and effective data are determined according to the fluctuation degree of each digital signal item in each data group; according to the digital signal item in at least one effective data packet, replacing the digital signal item in the noise data packet to obtain a digital signal sequence after interference removal; then fitting the digital signal sequence by adopting a polynomial fitting method, and subtracting the corresponding fitting value from each digital signal item to obtain a digital signal sequence after direct current is removed; performing fast Fourier transform on the digital signal sequence without direct current, clustering each signal point in the Fourier transformed signal according to a preset cluster number, obtaining a first detection threshold according to a cluster center calculated after clustering, calculating by adopting a preset algorithm to obtain second detection thresholds respectively corresponding to each signal point in the Fourier transformed signal, and determining a target signal point and a noise signal point in the Fourier transformed signal according to the first detection threshold and the second detection threshold. The technical scheme of the embodiment of the invention can effectively eliminate the interference signal in the intermediate frequency measurement signal, eliminate the direct current component in the digital signal sequence matched with the intermediate frequency measurement signal, improve the accuracy of the millimeter wave radar module on the detection result of the target signal point and reduce the false detection rate of the constant false alarm detection algorithm.

EXAMPLE five

Fig. 6 is a structural diagram of a detection apparatus for millimeter wave radar signals according to a fifth embodiment of the present invention, where the apparatus includes: an obtaining module 610, a first detection threshold calculation module 620, a second detection threshold calculation module 630, and a determining module 640, wherein:

the acquisition module 610 is configured to acquire a post-fourier-transform signal matched with an intermediate-frequency measurement signal detected by the millimeter wave radar module, where the post-fourier-transform signal includes a plurality of signal points;

a first detection threshold calculation module 620, configured to perform clustering processing on each signal point in the fourier-transformed signal according to a preset cluster number, and obtain a first detection threshold corresponding to the fourier-transformed signal according to at least one cluster center obtained after clustering;

a second detection threshold calculation module 630, configured to calculate, by using a preset algorithm, second detection thresholds corresponding to signal points in the fourier-transformed signal respectively;

a determining module 640, configured to determine a target signal point and a noise signal point in the fourier transformed signal according to the first detection threshold and the second detection threshold.

On the basis of the above embodiments, the first detection threshold calculation module 620 includes:

the initialization unit is used for initializing cluster centers respectively corresponding to the clustering clusters according to the preset cluster number;

the clustering unit is used for carrying out multiple clustering processing on each signal point in the Fourier transformed signal by taking the initialized cluster center as a starting point, and circularly iterating to obtain stable cluster centers respectively corresponding to each cluster;

a first detection threshold determining unit configured to determine the first detection threshold according to a stable cluster center having a largest signal value among the stable cluster centers;

the first detection threshold determining unit is specifically configured to use a first threshold constant as a first detection threshold when a stable cluster center with a largest signal value is less than or equal to the first threshold constant; when the center of the stable cluster with the maximum signal value is larger than a first threshold constant and smaller than a second threshold constant, taking the center of the stable cluster with the maximum signal value as a first detection threshold; when the center of the stable cluster with the maximum signal value is larger than or equal to a second threshold constant, taking the second threshold constant as a first detection threshold; wherein the first threshold constant is less than the second threshold constant;

a maximum signal value selecting unit configured to select a maximum signal value from signal values corresponding to all signal points included in the post-fourier-transform signal;

the preset proportion coefficient acquisition unit is used for acquiring preset proportion coefficients corresponding to the clustering clusters respectively according to the number of the preset clusters;

and the cluster center determining unit is used for taking the product of the maximum signal value and each preset proportionality coefficient as the cluster center corresponding to each cluster.

The determining module 640 includes:

a current processing signal point obtaining unit, configured to sequentially obtain one signal point in the fourier transformed signal as a current processing signal point;

a target signal point determining unit, configured to use the currently processed signal point as a target signal point if a signal value of the currently processed signal point is greater than or equal to the first detection threshold and greater than or equal to a second detection threshold that is matched with the currently processed signal point;

and the all-signal-point processing unit is used for returning and executing the operation of sequentially acquiring one signal point in the Fourier-transformed signal as the current processing signal point until the processing of all the signal points in the Fourier-transformed signal is finished.

The obtaining module 610 includes:

the digital signal sequence acquisition unit is used for acquiring a digital signal sequence matched with the intermediate frequency measurement signal detected by the millimeter wave radar module;

the transformation unit is used for carrying out fast Fourier transformation on the digital signal sequence to obtain a Fourier transformed signal;

a grouping unit for dividing the digital signal sequence into a plurality of data packets, each data packet including a plurality of digital signal items;

a noise data packet determination unit for determining a noise data packet and a valid data packet in each data packet according to a fluctuation degree of each digital signal item in each data packet;

the replacing unit is used for replacing the digital signal item in the noise data packet according to the digital signal item in at least one effective data packet to obtain a digital signal sequence after interference removal;

the fitting unit is used for fitting the digital signal sequence after interference removal by adopting a polynomial fitting method to obtain fitting values respectively corresponding to all digital signal items in the digital signal sequence after interference removal;

and the direct current signal removing unit is used for subtracting the corresponding fitting value from each digital signal item to obtain a direct current-removed digital signal sequence corresponding to the interference-removed digital signal sequence.

The detection device of the millimeter wave radar signal further includes:

and the distance calculation module is used for calculating the distance between the millimeter wave radar module and a target object according to the position of the target signal point in the signal after the Fourier transform.

The millimeter wave radar signal detection device provided by the embodiment of the invention can execute the millimeter wave radar signal detection method provided by any embodiment of the invention, and has corresponding functional modules and beneficial effects of the execution method.

EXAMPLE six

Fig. 7 is a schematic structural diagram of a millimeter wave radar module according to a sixth embodiment of the present invention, as shown in fig. 7, the millimeter wave radar module includes a processor 710, a memory 720, an input device 730, an output device 740, an antenna module 750, a mixer 760, and an analog-to-digital converter 770.

The antenna module 750 is configured to send an electromagnetic wave signal to a surrounding environment and receive an echo signal matched with the electromagnetic wave signal;

a mixer 760, configured to mix the electromagnetic wave signal with the echo signal to obtain an intermediate frequency measurement signal;

the analog-to-digital converter 770 is configured to perform analog-to-digital conversion on the intermediate frequency measurement signal to obtain a digital signal sequence;

the number of processors 710 in the millimeter wave radar module may be one or more, and one processor 710 is taken as an example in fig. 7; the processor 710, the memory 720, the input device 730, the output device 740, the antenna module 750, the mixer 760 and the analog-to-digital converter 770 in the millimeter wave radar module may be connected by a bus or other means, and fig. 7 illustrates the bus connection.

The memory 720 is a computer-readable storage medium that can be used to store software programs, computer-executable programs, and modules, such as program instructions/modules corresponding to the detection method of millimeter-wave radar signals in the embodiment of the present invention (for example, the acquisition module 610, the first detection threshold calculation module 620, the second detection threshold calculation module 630, and the determination module 640 in the detection apparatus of millimeter-wave radar signals). The processor 710 executes various functional applications and data processing of the millimeter wave radar module by executing software programs, instructions and modules stored in the memory 720, so as to implement the above-mentioned detection method of the millimeter wave radar signal. That is, the program when executed by the processor implements:

The memory 720 may mainly include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application program required for at least one function; the storage data area may store data created according to the use of the terminal, and the like. Further, the memory 720 may include high speed random access memory, and may also include non-volatile memory, such as at least one magnetic disk storage device, flash memory device, or other non-volatile solid state storage device. In some examples, memory 720 may further include memory located remotely from processor 710, which may be connected to the millimeter wave radar module via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.

The input device 730 may be used to receive information such as the model of the drone input by the user. The output device 740 may include various information output interfaces, for example, a CAN bus interface or an RS232 interface, etc., to output the measured position information of the target object.

EXAMPLE seven

Fig. 8 is a schematic structural diagram of a mobile device in a seventh embodiment of the present invention, where the mobile device includes an unmanned aerial vehicle, an unmanned ship, and other devices.

As shown in fig. 8, the removable device 801 is configured with a millimeter wave radar module 802 according to any of the embodiments of the present invention. In this embodiment, the millimeter wave radar module 802 obtains the post-fourier-transform signal matched with the intermediate frequency measurement signal detected by the millimeter wave radar module, clusters each signal point in the post-fourier-transform signal according to a preset cluster number, obtains a first detection threshold corresponding to the post-fourier-transform signal according to at least one cluster center obtained after clustering, calculates a second detection threshold corresponding to each signal point in the post-fourier-transform signal by using a preset algorithm, and determines a target signal point and a noise signal point in the post-fourier-transform signal according to the first detection threshold and the second detection threshold, so that accuracy of a detection result of the millimeter wave radar module on the target signal point can be improved.

Example eight

The eighth embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, where the computer program is executed by a processor to implement the method according to any embodiment of the present invention. Of course, the embodiments of the present invention provide a computer-readable storage medium, which can perform related operations in a detection method of a millimeter wave radar signal according to any embodiment of the present invention. That is, the program when executed by the processor implements:

From the above description of the embodiments, it is obvious for those skilled in the art that the present invention can be implemented by software and necessary general hardware, and certainly, can also be implemented by hardware, but the former is a better embodiment in many cases. Based on such understanding, the technical solutions of the present invention may be embodied in the form of a software product, which can be stored in a computer-readable storage medium, such as a floppy disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a FLASH Memory (FLASH), a hard disk or an optical disk of a computer, and includes several instructions for enabling a computer device (which may be a personal computer, a server, or a network device) to execute the methods according to the embodiments of the present invention.

It should be noted that, in the above embodiment of the detection apparatus for millimeter wave radar signals, the included units and modules are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be realized; in addition, specific names of the functional units are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present invention.

It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A detection method of a millimeter wave radar signal, characterized by comprising:

2. The method of claim 1, wherein clustering signal points in the fourier transformed signal according to a preset number of clusters, and obtaining a first detection threshold corresponding to the fourier transformed signal according to at least one cluster center obtained after clustering, comprises:

3. The method of claim 2, wherein initializing cluster centers corresponding to the respective cluster clusters according to a predetermined number of clusters comprises:

4. The method of claim 2, wherein determining the first detection threshold based on a stable cluster center of each stable cluster center having a largest signal value comprises:

if the stable cluster center with the maximum signal value is smaller than or equal to a first threshold constant, taking the first threshold constant as a first detection threshold;

if the stable cluster center with the maximum signal value is larger than a first threshold constant and smaller than a second threshold constant, taking the stable cluster center with the maximum signal value as a first detection threshold;

if the center of the stable cluster with the maximum signal value is larger than or equal to a second threshold constant, taking the second threshold constant as a first detection threshold;

5. The method of any of claims 1-4, wherein determining a target signal point in the post-Fourier transformed signal based on the first detection threshold and the second detection threshold comprises:

6. The method of claim 1, wherein obtaining the post-fourier-transform signal matched to the intermediate frequency measurement signal detected by the millimeter wave radar module comprises:

7. The method of claim 6, further comprising, before performing a fast fourier transform on the sequence of digital signals to obtain a fourier transformed signal:

8. The method of claim 7, further comprising, after obtaining the de-interfered digital signal sequence:

9. The method of claim 1, further comprising, after determining a target signal point in the post-fourier-transform signal based on the first detection threshold and the second detection threshold:

10. A detection device for a millimeter wave radar signal, comprising:

11. A millimeter-wave radar module, comprising:

one or more processors;

storage means for storing one or more programs;

when executed by the one or more processors, cause the one or more processors to implement a method of detecting millimeter wave radar signals as recited in any of claims 1-9.

12. A computer-readable storage medium on which a computer program is stored, the program, when being executed by a processor, implementing a method for detecting a millimeter-wave radar signal according to any one of claims 1 to 9.

13. A removable device, characterized in that the millimeter wave radar module according to claim 11 is provided thereon.