CN113740810A - Radar signal enhancement method, system and equipment - Google Patents

Radar signal enhancement method, system and equipment Download PDF

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CN113740810A
CN113740810A CN202110998685.3A CN202110998685A CN113740810A CN 113740810 A CN113740810 A CN 113740810A CN 202110998685 A CN202110998685 A CN 202110998685A CN 113740810 A CN113740810 A CN 113740810A
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signal
radar
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radar signal
segment
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CN113740810B (en
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侯兴松
要晓迪
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Xian Jiaotong University
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/28—Details of pulse systems
    • G01S7/285—Receivers
    • G01S7/292—Extracting wanted echo-signals
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/41—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section

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  • Computer Networks & Wireless Communication (AREA)
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  • Radar, Positioning & Navigation (AREA)
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  • Radar Systems Or Details Thereof (AREA)

Abstract

The invention discloses a method, a system and equipment for enhancing radar signals, wherein the method comprises the following steps: determining the number N of local signal segmentsLMAnd a width w; the local signal segment is a signal segment containing a local peak value; according to the determined number N of local signal segmentsLMThe width w is used for recursively searching a local peak value in the radar signal to be enhanced and marking a signal segment containing the local peak value to obtain a marked signal segment; segmenting the radar signal to be enhanced according to the marked signal segment to obtain a segmented radar signal; performing normalization processing on the segmented radar signal by adopting a local peak value in the marking signal section to obtain an enhanced radar signal; the invention effectively avoids the assumption of weak long-distance template signals and avoids the influence of the relative position of strong clutter and the template signals; the relative amplitude of the target signal is effectively improved, and the signal-to-noise ratio is improved; by not changing the signal ratio in the segment, excessive irrelevant signals can be effectively avoidedPrevents the overall signal-to-noise ratio from deteriorating.

Description

Radar signal enhancement method, system and equipment
Technical Field
The invention belongs to the technical field of radar signal processing, and particularly relates to a radar signal enhancement method, a system and equipment.
Background
According to the radar basic equation, the level of a target signal received by a radar is influenced by the distances among a transmitting antenna, a target and a receiving antenna, the reflection generated by the target close to a radar antenna system is usually stronger than that generated by the target far away from the radar antenna system, and the effect is enhanced by multipath reflection; particularly, in a scene of static human body respiration detection and the like, clutter with energy far larger than a target respiration signal is generated by possible interference of a moving target and the like, and the condition can cause missed detection or false detection of the target.
Weak signal enhancement methods can solve the above problems, such as: the time gain method (Bahl V, padmanaham V, Balachandran a. location-Aware Services In an In-Building Environment [ J ]) achieves enhancement of weak signals by multiplying input signals by weights that are positively correlated with fast time; an operation of continuously performing 'searching for a maximum value and normalizing an interval signal by taking the maximum value as a boundary' according to a fast time sequence from front to back by advance normalization (Rov ň akov a J, Kocur D.Weak signal enhancement in radial signal processing [ C ]//20th International Conference radioelktronika 2010.IEEE,2010: 1-4); however, the existing methods have defects, in some scenes such as static human body respiration detection, when the energy of the stray wave is higher than the energy of the target respiration signal and is behind the target signal, the two methods are due to the assumption that the echo signal of the long-distance target is weak, and the signal-to-noise ratio is deteriorated; in addition, the automatic gain control method (Shan T J, Kailath T.adaptive algorithms with an automatic gain control feature [ J ]. IEEE Transactions on circuits and systems,1988,35(1):122 and 127 ]) adaptively enhances the signal with small energy, and when applied to the enhancement of the radar weak signal, the method is not only influenced by the selection of the energy calculation window length, but also easily amplifies the part of the non-target signal, and is difficult to enhance the target signal in a targeted manner.
Disclosure of Invention
Aiming at the technical problems in the prior art, the invention provides a radar signal enhancement method, a system and equipment, aiming at solving the technical problems that the conventional radar signal enhancement method is easily influenced by the relative position of clutter and a target signal or is easily caused by a non-target signal part method.
In order to achieve the purpose, the invention adopts the technical scheme that:
the invention provides a radar signal enhancement method, which comprises the following steps:
determining the number N of local signal segmentsLMAnd a width w; whereinThe local signal segment is a signal segment containing a local peak value;
according to the determined number N of local signal segmentsLMThe width w is used for recursively searching a local peak value in the radar signal to be enhanced and marking a signal segment containing the local peak value to obtain a marked signal segment;
segmenting the radar signal to be enhanced according to the marked signal segment to obtain a segmented radar signal;
and carrying out normalization processing on the segmented radar signal by adopting a local peak value in the marking signal section to obtain the enhanced radar signal.
Further, the process of determining the number and width of the local signal segments specifically includes the following steps:
determining the number of local signal segments according to the number of estimated targets and the number of non-target scatterers in the actual acquisition environment of the radar signal to be enhanced;
and determining the width of the local signal segment according to the radar pulse width reflected by the target.
Furthermore, the number of the local signal segments is the sum of the number of the estimated targets and the number of the non-target scatterers in the actual acquisition environment of the radar signal to be enhanced.
Further, according to the determined number N of the local signal segmentsLMAnd width w, recursively searching a local peak value in the radar signal to be enhanced, marking a signal segment containing the local peak value, and obtaining a process of marking the signal segment, specifically as follows:
s1, initializing the number P of marked signal segments including local peak values to 0; that is, the number P of marked mark signal segments is 0;
s2, if the number P of marked mark signal segments and the number N of determined local signal segmentsLMIf yes, returning the marked mark signal segment, and ending S2; otherwise, go to S3;
s3, making P equal to P +1, and searching the maximum modulus value of the radar signal in the unmarked part of the radar signal to be enhanced; according to the width w of the determined local signal segment, taking a signal point corresponding to the currently searched mode maximum value as a center, and unmarking the radar signal to be enhancedMarking part of the signals to obtain a current marking signal section; wherein the starting position of the current marking signal segment is recorded as
Figure BDA0003234783680000031
The end position is recorded as
Figure BDA0003234783680000032
S4, if P is 1, directly switching to S2 after acquiring the current mark signal segment;
s5, if the number p of any marked flag signal segments satisfies: p is more than or equal to 1 and less than or equal to P-1; and the starting position of the current marking signal segment is recorded as
Figure BDA0003234783680000033
And the end position is recorded as
Figure BDA0003234783680000034
Satisfies the following conditions:
Figure BDA0003234783680000035
and is
Figure BDA0003234783680000036
Go to S2;
wherein the content of the first and second substances,
Figure BDA0003234783680000037
the starting position of the p-th marked signal segment;
Figure BDA0003234783680000038
the end position of the p-th marked signal segment;
s6, if there is any number p of marked mark signal segments: p is more than or equal to 1 and less than or equal to P-1, so that
Figure BDA0003234783680000039
Then order
Figure BDA00032347836800000310
P is P-1, andtransitioning to S3;
s7, if there is any number p of marked mark signal segments: p is more than or equal to 1 and less than or equal to P-1, so that
Figure BDA00032347836800000311
Then order
Figure BDA00032347836800000312
P-1 and goes to S3.
Further, according to the mark signal segment, the radar signal to be enhanced is segmented to obtain a segmented radar signal, which specifically comprises the following steps:
marking and sequencing the starting and stopping positions of the marking signal segments according to a time sequence to obtain a position time sequence of the marking signal segments;
obtaining a segmented marking value of the radar signal to be enhanced according to the position time sequence of the marking signal segment;
and segmenting the radar signal to be enhanced according to the segmented marking value of the radar signal to be enhanced to obtain the segmented radar signal.
Further, the expression of the position time series of the mark signal segment is:
Figure BDA00032347836800000313
wherein the content of the first and second substances,
Figure BDA00032347836800000314
the starting position time of the qth marking signal segment;
Figure BDA00032347836800000315
the end position time of the q mark signal segment;
the expression of the segmentation mark value of the radar signal to be enhanced is as follows:
Figure BDA0003234783680000041
wherein the content of the first and second substances,
Figure BDA0003234783680000042
marking the value of the q segment of the radar signal to be enhanced;
Figure BDA0003234783680000043
is the start position time of the q +1 th mark signal segment.
Further, segmenting the radar signal to be enhanced according to the segmentation mark value of the radar signal to be enhanced to obtain a segmented radar signal; the segmented radar signals are P segments in total, and the expression of each segmented radar signal is as follows:
Figure BDA0003234783680000044
Figure BDA0003234783680000045
…，
Figure BDA0003234783680000046
…，
Figure BDA0003234783680000047
wherein the content of the first and second substances,
Figure BDA0003234783680000048
the first section of radar signal in the radar signal to be enhanced;
Figure BDA0003234783680000049
a first point of the first section of radar signal in the radar signal to be enhanced;
Figure BDA00032347836800000410
the last point of the l-th section of radar signal in the radar signal to be enhanced is obtained;
Figure BDA00032347836800000411
the radar signals of the P section in the radar signals to be enhanced;
Figure BDA00032347836800000412
a first point of a P-th section of radar signal in the radar signal to be enhanced; h isb(tend) The last point of the radar signal to be enhanced.
Further, the expression of the enhanced radar signal is as follows:
Figure BDA00032347836800000413
Figure BDA0003234783680000051
wherein h isE(t) is the enhanced radar signal;
Figure BDA0003234783680000052
the signal is the l-th section radar signal in the enhanced signal; max (#) is the maximum operation; and | | x | is a modulo operation.
The invention also provides a radar signal enhancement system, comprising:
a local signal segment module for determining the number N of local signal segmentsLMAnd a width w; the local signal segment is a signal segment containing a local peak value;
a marking module for marking the number N of the determined local signal segmentsLMThe width w is used for recursively searching a local peak value in the radar signal to be enhanced and marking a signal segment containing the local peak value to obtain a marked signal segment;
the segmentation module is used for segmenting the radar signal to be enhanced according to the marking signal segment to obtain a segmented radar signal;
and the normalization enhancing module is used for performing normalization processing on the segmented radar signals by adopting the local peak values in the marking signal section to obtain the enhanced radar signals.
The invention also provides a radar signal enhancement device which comprises a memory and a computer program which is stored in the memory at one stage and can run on the processor, wherein the processor realizes the radar signal enhancement method when executing the computer program.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a radar signal enhancement method, which recursively searches a corresponding marking signal section in a radar signal to be enhanced through a signal section containing a local peak value, thereby effectively avoiding the assumption that a long-distance template signal is weak and avoiding the influence of a relative position of a strong clutter and the template signal; according to the marked signal segment, the radar signal to be enhanced is segmented, normalization processing is carried out on the segmented radar signal, weak signal enhancement is achieved, the radar signal after normalization processing is in the same order of magnitude, the relative amplitude of a target signal is effectively improved, and the signal-to-noise ratio is improved; compared with the existing automatic gain control method, the method can effectively avoid the amplification of excessive irrelevant signals and prevent the deterioration of the integral signal-to-noise ratio by not changing the signal ratio in the section.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art are briefly introduced below; it is obvious that the drawings in the following description are some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.
FIG. 1 is a flow chart of a method of radar signal enhancement according to the present invention;
fig. 2(a) is a schematic diagram of a two-dimensional signal after removing a static background and a stable noise wave in example 1, namely a radar signal to be enhanced;
FIG. 2(b) is a schematic diagram of the radar signal to be enhanced in example 1 after being enhanced by the method in example 1;
FIG. 2(c) is a schematic diagram of the radar signal to be enhanced in example 1 after being enhanced by the automatic gain control method;
FIG. 2(d) is a schematic diagram of the radar signal to be enhanced in example 1 after being enhanced by the Advance normalized algorithm;
fig. 3(a) is a schematic diagram of a single-echo signal after removing a static background and a stable clutter in example 2, namely a radar signal to be enhanced;
FIG. 3(b) is a schematic diagram of the radar signal to be enhanced in example 2 after being enhanced by the method in example 2;
FIG. 3(c) is a schematic diagram of the enhanced radar signal of example 2 after being enhanced by the automatic gain control method;
fig. 3(d) is a schematic diagram of the radar signal to be enhanced in example 2 after being enhanced by the advanced normalized algorithm.
Detailed Description
In order to make the purpose, technical effect and technical solution of the embodiments of the present invention clearer, the following clearly and completely describes the technical solution of the embodiments of the present invention with reference to the drawings in the embodiments of the present invention; it is to be understood that the described embodiments are only some of the embodiments of the present invention. Other embodiments, which can be derived by one of ordinary skill in the art from the disclosed embodiments without inventive faculty, are intended to be within the scope of the invention.
As shown in fig. 1, the present invention provides a radar signal enhancement method, which includes the following steps:
step 1, collecting original radar echo signal h of life detection radarb(t), original radar echo signal hb(t) as radar signal to be enhanced; determining the number N of local signal segmentsLMAnd a width w; the local signal segment is a signal segment containing a local peak value; the process of determining the number and the width of the local signal segments specifically comprises the following steps:
determining the number of local signal segments according to the number of estimated targets and the number of non-target scatterers in the actual acquisition environment of the radar signal to be enhanced; the number of the local signal segments is the sum of the number of the estimated targets and the number of the non-target scatterers in the actual acquisition environment of the radar signal to be enhanced; and determining the width of the local signal segment according to the radar pulse width reflected by the target.
Step 2, according to the determined number N of the local signal segmentsLMThe width w is used for recursively searching a local peak value in the radar signal to be enhanced and marking a signal segment containing the local peak value to obtain a marked signal segment; i.e. in the original radar echo signal hb(t) unmarked part, searching for a modulo maximum, marking a signal segment of width w centered at the position of the modulo maximum.
The specific process is as follows:
s1, initializing the number P of marked signal segments including local peak values to 0; that is, the number P of marked mark signal segments is 0;
s2, if the number P of marked mark signal segments and the number N of determined local signal segmentsLMIf yes, returning the marked mark signal segment, and ending S2; otherwise, go to S3.
S3, making P equal to P +1, and searching the maximum modulus value of the radar signal in the unmarked part of the radar signal to be enhanced; marking the unmarked part of the radar signal to be enhanced by taking a signal point corresponding to the currently searched mode maximum value as a center according to the width w of the determined local signal segment to obtain a current marked signal segment; wherein the starting position of the current marking signal segment is recorded as
Figure BDA0003234783680000071
The end position is recorded as
Figure BDA0003234783680000072
Judging whether the marked signal segment of the new mark is overlapped with the marked mark signal, if so, returning to S2, otherwise, returning to S3, and the specific process is as follows:
s4, if P is 1, directly switching to S2 after acquiring the current mark signal segment; here, when P ═ 1 indicates that only one segment of the mark signal segment is marked, and therefore, the marked signal segments are unlikely to overlap, the process may directly proceed to S2 to determine whether to start the next search for a mark.
S5, if the number p of any marked flag signal segments satisfies: p is more than or equal to 1 and less than or equal to P-1; and the starting position of the current marking signal segment is recorded as
Figure BDA0003234783680000081
And the end position is recorded as
Figure BDA0003234783680000082
Satisfies the following conditions:
Figure BDA0003234783680000083
and is
Figure BDA0003234783680000084
Go to S2; in step S5, it indicates that there is no overlap phenomenon in the marked P-1 mark signal segments; wherein the content of the first and second substances,
Figure BDA0003234783680000085
the starting position of the p-th marked signal segment;
Figure BDA0003234783680000086
the end position of the p-th marked signal segment.
S6, if there is any number p of marked mark signal segments: p is more than or equal to 1 and less than or equal to P-1, so that
Figure BDA0003234783680000087
Then order
Figure BDA0003234783680000088
P-1 and go to S3; in step S6, the P-th flag signal segment indicating the current flag overlaps with one of the P-1 flag signal segments already marked, and the specific overlap form is: the segment head of the P-th marking signal segment is located in the P-th marking signal segment.
S7, if there is any marked mark signal segment number p: p is more than or equal to 1 and less than or equal to P-1, so that
Figure BDA0003234783680000089
Then order
Figure BDA00032347836800000810
P-1 and go to S3; in step S7, the P-th flag signal segment indicating the current flag overlaps with one of the P-1 flag signal segments already marked, and the specific overlap form is: the segment end of the P-th marking signal segment is located in the P-th marking signal segment.
Step 3, segmenting the radar signal to be enhanced according to the marked signal segment to obtain a segmented radar signal; the specific process is as follows:
step 31, marking and sequencing the starting and ending positions of the marked signal segments according to a time sequence to obtain a position time sequence of the marked signal segments; wherein, the expression of the position time sequence of the marking signal segment is as follows:
Figure BDA00032347836800000811
wherein the content of the first and second substances,
Figure BDA00032347836800000812
the starting position time of the qth marking signal segment;
Figure BDA00032347836800000813
the end position time of the qth mark signal segment.
Step 32, obtaining a segmented marking value of the radar signal to be enhanced according to the position time sequence of the marking signal segment; the expression of the segmentation mark value of the radar signal to be enhanced is as follows:
Figure BDA0003234783680000091
wherein the content of the first and second substances,
Figure BDA0003234783680000092
marking the value of the q segment of the radar signal to be enhanced;
Figure BDA0003234783680000093
is the start position time of the q +1 th mark signal segment.
Step 33, segmenting the radar signal to be enhanced according to the segmentation mark value of the radar signal to be enhanced to obtain a segmented radar signal; the segmented radar signals are P segments in total, and the expression of each segmented radar signal is as follows:
Figure BDA0003234783680000094
Figure BDA0003234783680000095
…，
Figure BDA0003234783680000096
…，
Figure BDA0003234783680000097
wherein the content of the first and second substances,
Figure BDA0003234783680000098
the first section of radar signal in the radar signal to be enhanced;
Figure BDA0003234783680000099
a first point of the first section of radar signal in the radar signal to be enhanced;
Figure BDA00032347836800000910
the last point of the l-th section of radar signal in the radar signal to be enhanced is obtained;
Figure BDA00032347836800000911
the radar signals of the P section in the radar signals to be enhanced;
Figure BDA00032347836800000912
a first point of a P-th section of radar signal in the radar signal to be enhanced; h isb(tend) The last point of the radar signal to be enhanced.
Suppose there are a total of 4096 points, t, in the radar signal to be enhancedend4096; according to step 31, the obtained P mark segment start positions
Figure BDA00032347836800000913
Specifically (100, 200), (320, 400), …, (2000,2400), …, (3800, 4000); then when q is 1, obtain
Figure BDA0003234783680000101
Further obtain
Figure BDA0003234783680000102
And the analogy is repeated, so that the expression of the P-th section of radar signals in the radar signals to be enhanced can be obtained.
Step 4, adopting local peak values in the marked signal section to carry out normalization processing on the segmented radar signals to obtain enhanced radar signals; wherein, the expression of the enhanced radar signal is as follows:
Figure BDA0003234783680000103
Figure BDA0003234783680000104
wherein h isE(t) is the enhanced radar signal;
Figure BDA0003234783680000105
for enhancing postambleThe l-th segment of the signal; max (#) is the maximum operation; and | | x | is a modulo operation.
The invention also provides a radar signal enhancement system, which comprises a local signal segment module, a marking module, a segmentation module and a normalization enhancement module:
a local signal segment module for determining the number N of local signal segmentsLMAnd a width w; the local signal segment is a signal segment containing a local peak value;
a marking module for marking the number N of the determined local signal segmentsLMThe width w is used for recursively searching a local peak value in the radar signal to be enhanced and marking a signal segment containing the local peak value to obtain a marked signal segment;
the segmentation module is used for segmenting the radar signal to be enhanced according to the marking signal segment to obtain a segmented radar signal;
and the normalization enhancing module is used for performing normalization processing on the segmented radar signals by adopting the local peak values in the marking signal section to obtain the enhanced radar signals.
The invention also provides a radar signal enhancement device, which comprises: a processor, a memory, and a computer program stored in the memory and executable on the processor, such as: and (5) a radar signal enhancement program. The processor, when executing the computer program, implements the steps in the above-mentioned radar signal enhancement method, such as: determining the number N of local signal segmentsLMAnd a width w; the local signal segment is a signal segment containing a local peak value; according to the determined number N of local signal segmentsLMThe width w is used for recursively searching a local peak value in the radar signal to be enhanced and marking a signal segment containing the local peak value to obtain a marked signal segment; segmenting the radar signal to be enhanced according to the marked signal segment to obtain a segmented radar signal; and carrying out normalization processing on the segmented radar signal by adopting a local peak value in the marking signal section to obtain the enhanced radar signal.
Alternatively, the processor implements the radar signal when executing the computer programEnhancing the functions of the modules in the equipment device, for example: a local signal segment module for determining the number N of local signal segmentsLMAnd a width w; the local signal segment is a signal segment containing a local peak value; a marking module for marking the number N of the determined local signal segmentsLMThe width w is used for recursively searching a local peak value in the radar signal to be enhanced and marking a signal segment containing the local peak value to obtain a marked signal segment; the segmentation module is used for segmenting the radar signal to be enhanced according to the marking signal segment to obtain a segmented radar signal; and the normalization enhancing module is used for performing normalization processing on the segmented radar signals by adopting the local peak values in the marking signal section to obtain the enhanced radar signals.
Illustratively, the computer program may be partitioned into one or more modules/units that are stored in the memory and executed by the processor to implement the invention. The one or more modules/units may be a series of computer program instruction segments capable of performing certain functions, which are used to describe the execution of the computer program in the radar signal enhancing device. For example, the computer program may be divided into a local signal segment module, a labeling module, a segmentation module, and a normalization enhancement module, and each module specifically functions as follows: a local signal segment module for determining the number N of local signal segmentsLMAnd a width w; the local signal segment is a signal segment containing a local peak value; a marking module for marking the number N of the determined local signal segmentsLMThe width w is used for recursively searching a local peak value in the radar signal to be enhanced and marking a signal segment containing the local peak value to obtain a marked signal segment; the segmentation module is used for segmenting the radar signal to be enhanced according to the marking signal segment to obtain a segmented radar signal; and the normalization enhancing module is used for performing normalization processing on the segmented radar signals by adopting the local peak values in the marking signal section to obtain the enhanced radar signals.
The radar signal enhancement device can be a desktop computer, a notebook, a palm computer, a cloud server and other computing devices. The radar signal enhancement apparatus may include, but is not limited to, a processor, a memory. It will be understood by those skilled in the art that the radar signal enhancement device, which is not limiting, may include more or fewer components than the radar signal enhancement device, or some components in combination, or different components, for example, the radar signal enhancement device may also include input-output devices, network access devices, buses, etc.
The processor may be a Central Processing Unit (CPU), other general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, etc. The general purpose processor may be a microprocessor or the processor may be any conventional processor or the like, the processor being the control center of the radar signal enhancing device, and various interfaces and lines connecting the various parts of the entire radar signal enhancing device.
The memory may be used to store the computer programs and/or modules, and the processor may implement the various functions of the radar signal enhancing apparatus by running or executing the computer programs and/or modules stored in the memory and invoking data stored in the memory.
The memory may mainly include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required by at least one function (such as a sound playing function, an image playing function, etc.), and the like; the storage data area may store data (such as audio data, a phonebook, etc.) created according to the use of the cellular phone, and the like.
In addition, the memory may include high speed random access memory, and may also include non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) card, a flash memory card (FlashCard), at least one disk storage device, a flash memory device, or other volatile solid state storage device.
According to the radar signal enhancement method, the purpose of signal enhancement is to enhance the echo of a target while not enhancing the echo of a non-target scatterer as much as possible; in the invention, the signal local peak value is regarded as the pulse reflected by the possible target scatterer and the non-target scatterer with higher electromagnetic reflectivity, and the number of the signal segments containing the signal local peak value is equal to the sum of the estimated number of the possible target scatterers and the estimated number of the non-target scatterers; in principle, the number of signal segments cannot be too small, otherwise all target echoes may not be covered (enhanced); but not too large, which would otherwise enhance too many non-target signals.
Example 1
In embodiment 1, an example of an enhancement process of an echo signal of a certain life detection radar is given.
This embodiment 1 provides a radar signal enhancement method, where an enhancement object of the radar signal enhancement method described in this embodiment 1 is a one-dimensional radar signal; the echo signal of the life detection radar is in a two-dimensional matrix form and is formed by combining a plurality of single echoes, and each echo is a column of the matrix; therefore, when the echo signal of the life detection radar is enhanced, only one of the echoes is processed at a time, namely, one echo.
The method specifically comprises the following steps:
step 1, collecting original radar echo signals of a life detection radar, and removing static background and stable clutter in the original radar echo signals by a linear trend removing method or an exponential averaging method to obtain radar signals h to be enhancedb(t, τ); wherein t is electromagnetic propagation fast time, and tau is radar receiving slow time; determining the number N of local signal segmentsLMAnd a width w; wherein, the local signal segment is a signal segment containing a local peak.
In this embodiment 1, the electromagnetic propagation is performed at fast time dispersion t of 1,2, …,4096 and at slow time dispersion τ of 1,2, …, 1024; it will be clear to those skilled in the art that the electromagnetic propagation fast time t and the radar reception slow time τ may take other values; FIG. 2(a) shows the embodiment with the static removedA schematic diagram of a two-dimensional signal after a state background and a stable clutter, namely a radar signal to be enhanced; wherein the radar fast time sampling rate is fsThe slow time effective pulse repetition frequency was 32Hz at 32 GHz.
In this embodiment 1, to enhance the display contrast, the radar signal h to be enhancedb(t, τ) performing an absolute value operation before imaging; wherein t is the electromagnetic propagation fast time, and each electromagnetic propagation fast time unit is
Figure BDA0003234783680000131
By distance conversion formula
Figure BDA0003234783680000132
Obtaining the distance between the target and the radar; wherein c is the propagation speed of the electromagnetic wave; tau is the radar receiving slow time, the unit of the radar receiving slow time is a track, one track is the radar generating and receiving one echo, and the two-dimensional matrix is expressed as a column.
In this embodiment 1, the distance between the detected person (target) and the radar is about 1.5m, and the distance conversion formula is used
Figure BDA0003234783680000141
Calculating to obtain that the target weak respiration signal is positioned in the radar signal h to be enhancedbLine 302 of (t, τ) and its vicinity; as can be seen from fig. 2(a), there is a signal with approximately periodic variation in brightness near 320 rows, i.e., the solid-line frame region of fig. 2 (a); a non-stationary clutter region with large brightness cross and wholly presenting a 'wave shape', namely a dashed line frame region shown in figure 2(a), exists below the grating; wherein, the larger energy is concentrated and distributed between the columns of 280-380 and 600-680, i.e. the dotted-line frame region in fig. 2 (a).
In this embodiment 1, the number of local signal segments is determined according to the number of estimated targets and the number of non-eye scatterers in the actual acquisition environment of the radar signal to be enhanced; determining the width of a local signal section according to the radar pulse width reflected by the target and the thickness of the chest cavity of the human body; setting the number N of local signal segmentsLM6, i.e. the total number of targets and clutter in a single echoNo more than 6; setting the width w of the local signal segment to be 20; the number of such local signal segments, N, will be clear to a person skilled in the artLMAnd the width w may take other values.
Step 2, according to the determined number N of the local signal segmentsLMAnd width w of radar signal h to be enhancedb(t, τ), τ is 1,2, …,1024, and a signal segment containing the local peak is marked to obtain a marked signal segment.
The specific process is as follows:
s1, initializing the number P of marked signal segments including local peak values to 0; that is, the number P of marked mark signal segments is 0;
s2, if the number P of marked mark signal segments and the number N of determined local signal segmentsLMSame, i.e. p ═ NLM(ii) a Or radar signal h to be enhancedb(t, τ) are marked, then returning to the marked marking signal segment, and ending S2; otherwise, go to S3.
S3, making P equal to P +1, and searching the maximum modulus value of the radar signal in the unmarked part of the radar signal to be enhanced; marking the unmarked part of the radar signal to be enhanced by taking a signal point corresponding to the currently searched mode maximum value as a center according to the width w of the determined local signal segment to obtain a current marked signal segment; wherein the starting position of the current marking signal segment is recorded as
Figure BDA0003234783680000142
The end position is recorded as
Figure BDA0003234783680000143
Wherein the content of the first and second substances,
Figure BDA0003234783680000144
judging whether the marked signal segment of the new mark is overlapped with the marked mark signal, if so, returning to S2, otherwise, returning to S3, and the specific process is as follows:
s4, when P is 1, the current flag signal segment is acquired, and the process proceeds to S2.
S5, if the number p of any marked flag signal segments satisfies: p is more than or equal to 1 and less than or equal to P-1; and the starting position of the current marking signal segment is recorded as
Figure BDA0003234783680000151
And the end position is recorded as
Figure BDA0003234783680000152
Satisfies the following conditions:
Figure BDA0003234783680000153
and is
Figure BDA0003234783680000154
Go to S2;
wherein the content of the first and second substances,
Figure BDA0003234783680000155
the starting position of the p-th marked signal segment;
Figure BDA0003234783680000156
the end position of the p-th marked signal segment;
s6, if there is any number p of marked mark signal segments: p is more than or equal to 1 and less than or equal to P-1, so that
Figure BDA0003234783680000157
Then order
Figure BDA0003234783680000158
P-1 and go to S3;
s7, if there is any number p of marked mark signal segments: p is more than or equal to 1 and less than or equal to P-1, so that
Figure BDA0003234783680000159
Then order
Figure BDA00032347836800001510
P-1 and goes to S3.
And 3, segmenting the radar signal to be enhanced according to the marked signal segment to obtain a segmented radar signal, wherein the specific process is as follows:
step 31, marking and sequencing the starting and ending positions of the marked signal segments according to a time sequence to obtain a position time sequence of the marked signal segments; wherein, the expression of the position time sequence of the marking signal segment is as follows:
Figure BDA00032347836800001511
wherein the content of the first and second substances,
Figure BDA00032347836800001512
the starting position time of the qth marking signal segment;
Figure BDA00032347836800001513
the end position time of the qth mark signal segment.
Step 32, obtaining a segmented marking value of the radar signal to be enhanced according to the position time sequence of the marking signal segment; the expression of the segmentation mark value of the radar signal to be enhanced is as follows:
Figure BDA00032347836800001514
wherein the content of the first and second substances,
Figure BDA0003234783680000161
marking the value of the q segment of the radar signal to be enhanced;
Figure BDA0003234783680000162
is the start position time of the q +1 th mark signal segment.
Step 33, segmenting the radar signal to be enhanced according to the segmentation mark value of the radar signal to be enhanced to obtain a segmented radar signal; the segmented radar signals are P segments in total, and the expression of each segmented radar signal is as follows:
Figure BDA00032347836800001612
Figure BDA0003234783680000163
…，
Figure BDA0003234783680000164
…，
Figure BDA0003234783680000165
wherein, among others,
Figure BDA0003234783680000166
in order to life and detect the first section radar signal in the radar signal to be enhanced of the radar;
Figure BDA0003234783680000167
a first point of the first section of radar signal in the radar signal to be enhanced of the life detection radar;
Figure BDA0003234783680000168
the last point of the l section radar signal in the radar signal to be enhanced of the life detection radar;
Figure BDA0003234783680000169
in order to life and detect the P section radar signal in the radar signal to be strengthened of the radar;
Figure BDA00032347836800001610
a first point of a P-section radar signal in a radar signal to be enhanced of a life detection radar; h isb(tendτ) is the last point of the radar signal to be enhanced of the life detection radar.
Step 4, adopting local peak values in the marked signal section to carry out normalization processing on the segmented radar signals to obtain enhanced radar signals; wherein, the expression of the enhanced radar signal is as follows:
Figure BDA00032347836800001611
Figure BDA0003234783680000171
wherein h isE(t, τ) is an enhanced radar signal of the life detection radar;
Figure BDA0003234783680000172
the first section of radar signals in the enhanced signals of the life detection radar; max (#) is the maximum operation; and | | x | is a modulo operation.
Example 2
The principle of the embodiment 2 is basically the same as that of the embodiment 1, except that the radar signal to be enhanced in the embodiment 2 is a single echo; wherein, the single echo is the 315 th column, i.e. h, of the two-dimensional signal in FIG. 2(a)b(t,315), forming the observation in fig. 3(a), it can be seen that the 643 th fast time unit is the clutter with the largest energy in the whole echo, i.e. the dashed frame area in fig. 3(a) is the range where the clutter energy is concentrated; the 317 th fast time unit is the maximum value of the amplitude of the target signal, that is, the solid frame area in fig. 3(a) is the range of the target signal concentration, and the energy is far less than the strong clutter; the specific enhancement processing procedure is basically the same as the steps in embodiment 1, and is not described here again.
And (3) test results:
fig. 2(b) is a schematic diagram of a radar signal to be enhanced after being enhanced by the method described in embodiment 1, and fig. 3(b) is a schematic diagram of a radar signal to be enhanced after being enhanced by the method described in embodiment 2; as can be seen from fig. 2(b) and fig. 3(b), although the target signal and the clutter energy are both enhanced, the energy ratio of the signal to the clutter is improved, and the extraneous signal below the clutter is not amplified too much.
In the embodiment 1 and the embodiment 2 of the present invention, the conventional advance normalization and automatic gain control methods are adopted as comparison methods, the enhancement effect on the two-dimensional signal is respectively shown in fig. 2(c) and fig. 2(d), and the enhancement effect on the single echo is respectively shown in fig. 3(c) and fig. 3 (d).
As can be seen from fig. 2(c), fig. 2(d), fig. 3(c) and fig. 3(d), the principle of advance normalization determines that the algorithm is not suitable for enhancing signals with clutter behind a target; for the signals in embodiments 1 and 2 of the present invention, the existing enhancement method not only fails to effectively enhance the signal above the strong clutter, but also obviously amplifies the irrelevant signal after the clutter; and the sliding window effect of automatic gain control enables the signal to be easily amplified to irrelevant signals, and the signal enhancement method has the same defects when being applied to the ground penetrating radar.
In the radar signal enhancement methods described in embodiments 1 and 2, the target has a certain pulse width and is close to the clutter, and since the signal gain is calculated based on a sliding window having a certain width, a small-amplitude signal between the target and the clutter is greatly enhanced, so that the interval between the clutter and the target is not obvious, and the clutter and the target are difficult to distinguish; and different from other two methods, the amplitude values of different channel echoes cannot be automatically normalized to the same range by automatic gain control, so that the energy of the finally enhanced B-scan signal is still concentrated in clutter positions of a few echoes.
The method for enhancing the radar weak signal comprises the steps of firstly setting the number and the width of local peak sections of the signal according to the possible number of targets and clutter, radar and target characteristics and the like in a priori mode; recursively searching signal peak values in the echoes until the number of marked peak value segments meets a preset value or all signals in the echoes are marked; finally normalizing the signals between every two adjacent local peak values; the relative amplitude between the target signal and the clutter can be enhanced in a targeted manner, and the purpose of improving the overall signal-to-noise ratio is achieved.
The above-described embodiment is only one of the embodiments that can implement the technical solution of the present invention, and the scope of the present invention is not limited by the embodiment, but includes any variations, substitutions and other embodiments that can be easily conceived by those skilled in the art within the technical scope of the present invention disclosed.

Claims (10)

1. A method for radar signal enhancement, comprising the steps of:
determining the number N of local signal segmentsLMAnd a width w; the local signal segment is a signal segment containing a local peak value;
according to the determined number N of local signal segmentsLMThe width w is used for recursively searching a local peak value in the radar signal to be enhanced and marking a signal segment containing the local peak value to obtain a marked signal segment;
segmenting the radar signal to be enhanced according to the marked signal segment to obtain a segmented radar signal;
and carrying out normalization processing on the segmented radar signal by adopting a local peak value in the marking signal section to obtain the enhanced radar signal.
2. The method of claim 1, wherein the process of determining the number and width of the local signal segments comprises:
determining the number of local signal segments according to the number of estimated targets and the number of non-target scatterers in the actual acquisition environment of the radar signal to be enhanced;
and determining the width of the local signal segment according to the radar pulse width reflected by the target.
3. The method of claim 2, wherein the number of local signal segments is a sum of the number of estimated targets and the number of non-target scatterers in the actual acquisition environment of the radar signal to be enhanced.
4. The method of claim 1, wherein the number N of the determined local signal segments is determined according to the determined number of the local signal segmentsLMAnd widthw, recursively searching a local peak value in the radar signal to be enhanced, and marking a signal segment containing the local peak value to obtain a process of marking the signal segment, specifically as follows:
s1, initializing the number P of marked signal segments including local peak values to 0; that is, the number P of marked mark signal segments is 0;
s2, if the number P of marked mark signal segments and the number N of determined local signal segmentsLMIf yes, returning the marked mark signal segment, and ending S2; otherwise, go to S3;
s3, making P equal to P +1, and searching the maximum modulus value of the radar signal in the unmarked part of the radar signal to be enhanced; marking the unmarked part of the radar signal to be enhanced by taking a signal point corresponding to the currently searched mode maximum value as a center according to the width w of the determined local signal segment to obtain a current marked signal segment; wherein the starting position of the current marking signal segment is recorded as
Figure FDA0003234783670000021
The end position is recorded as
Figure FDA0003234783670000022
S4, if P is 1, directly switching to S2 after acquiring the current mark signal segment;
s5, if the number p of any marked flag signal segments satisfies: p is more than or equal to 1 and less than or equal to P-1; and the starting position of the current marking signal segment is recorded as
Figure FDA0003234783670000023
And the end position is recorded as
Figure FDA0003234783670000024
Satisfies the following conditions:
Figure FDA0003234783670000025
and is
Figure FDA0003234783670000026
Go to S2;
wherein the content of the first and second substances,
Figure FDA0003234783670000027
the starting position of the p-th marked signal segment;
Figure FDA0003234783670000028
the end position of the p-th marked signal segment;
s6, if there is any number p of marked mark signal segments: p is more than or equal to 1 and less than or equal to P-1, so that
Figure FDA0003234783670000029
Then order
Figure FDA00032347836700000210
P-1 and go to S3;
s7, if there is any number p of marked mark signal segments: p is more than or equal to 1 and less than or equal to P-1, so that
Figure FDA00032347836700000211
Then order
Figure FDA00032347836700000212
P-1 and goes to S3.
5. The method according to claim 1, wherein the process of segmenting the radar signal to be enhanced according to the marker signal segment to obtain a segmented radar signal includes:
marking and sequencing the starting and stopping positions of the marking signal segments according to a time sequence to obtain a position time sequence of the marking signal segments;
obtaining a segmented marking value of the radar signal to be enhanced according to the position time sequence of the marking signal segment;
and segmenting the radar signal to be enhanced according to the segmented marking value of the radar signal to be enhanced to obtain the segmented radar signal.
6. The radar signal enhancement method of claim 5, wherein the expression of the position time series of the marker signal segment is:
Figure FDA00032347836700000213
wherein the content of the first and second substances,
Figure FDA00032347836700000214
the starting position time of the qth marking signal segment;
Figure FDA00032347836700000215
the end position time of the q mark signal segment;
the expression of the segmentation mark value of the radar signal to be enhanced is as follows:
Figure FDA0003234783670000031
wherein the content of the first and second substances,
Figure FDA0003234783670000032
marking the value of the q segment of the radar signal to be enhanced;
Figure FDA0003234783670000033
is the start position time of the q +1 th mark signal segment.
7. The radar signal enhancement method according to claim 6, wherein the radar signal to be enhanced is segmented according to the segmentation mark value of the radar signal to be enhanced to obtain a segmented radar signal; the segmented radar signals are P segments in total, and the expression of each segmented radar signal is as follows:
Figure FDA0003234783670000034
Figure FDA0003234783670000035
…，
Figure FDA0003234783670000036
…，
Figure FDA0003234783670000037
wherein the content of the first and second substances,
Figure FDA0003234783670000038
the first section of radar signal in the radar signal to be enhanced;
Figure FDA0003234783670000039
a first point of the first section of radar signal in the radar signal to be enhanced;
Figure FDA00032347836700000310
the last point of the l-th section of radar signal in the radar signal to be enhanced is obtained;
Figure FDA00032347836700000311
the radar signals of the P section in the radar signals to be enhanced;
Figure FDA00032347836700000312
a first point of a P-th section of radar signal in the radar signal to be enhanced; h isb(tend) The last point of the radar signal to be enhanced.
8. The method of claim 7, wherein the expression of the enhanced radar signal is:
Figure FDA0003234783670000041
Figure FDA0003234783670000042
wherein h isE(t) is the enhanced radar signal;
Figure FDA0003234783670000043
the signal is the l-th section radar signal in the enhanced signal; max (#) is the maximum operation; and | | x | is a modulo operation.
9. A radar signal enhancement system, comprising:
a local signal segment module for determining the number N of local signal segmentsLMAnd a width w; the local signal segment is a signal segment containing a local peak value;
a marking module for marking the number N of the determined local signal segmentsLMThe width w is used for recursively searching a local peak value in the radar signal to be enhanced and marking a signal segment containing the local peak value to obtain a marked signal segment;
the segmentation module is used for segmenting the radar signal to be enhanced according to the marking signal segment to obtain a segmented radar signal;
and the normalization enhancing module is used for performing normalization processing on the segmented radar signals by adopting the local peak values in the marking signal section to obtain the enhanced radar signals.
10. A radar signal enhancement device comprising a memory, a processor, a computer program stored in said memory and executable on said processor, characterized in that said processor, when executing said computer program, implements a radar signal enhancement method according to any one of claims 1 to 8.
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