CN113740810B - Radar signal enhancement method, system and equipment - Google Patents
Radar signal enhancement method, system and equipment Download PDFInfo
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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
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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
- G01S7/41—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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Abstract
The invention discloses a radar signal enhancement method, a system and equipment, wherein the method comprises the following steps: determining the number N of local signal segments LM A width w; the local signal section is a signal section containing local peak values; according to the number N of the determined local signal segments LM The width w is used for recursively searching local peaks in the radar signals to be enhanced, and marking signal segments containing the local peaks to obtain marked signal segments; segmenting the radar signal to be enhanced according to the marked signal segment to obtain a segmented radar signal; carrying out normalization processing on the segmented radar signals by adopting local peaks in the marked signal segments to obtain enhanced radar signals; the invention effectively avoids the assumption of weak remote template signals and avoids the influence of the relative positions of strong clutter and 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 section, the amplification of too many irrelevant signals can be effectively avoided, and the deterioration of the overall signal-to-noise ratio is prevented.
Description
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
As can be seen from the basic equation of the radar, the level of a target signal received by the radar is influenced by the distance among a transmitting antenna, a target and a receiving antenna, the reflection generated by the target close to the radar antenna system is often stronger than that generated by the target far away from the radar antenna system, and the multipath reflection further enhances the effect; in particular, in the situations of static human breath detection and the like, interference of a moving target and the like which may exist can generate clutter with energy far greater than that of a target respiratory signal, and the situation can cause missed detection or false detection of the target.
The weak signal enhancement method may solve the above problems, for example: the time gain method (Bahl V, padanabaham V, barachandran a. Location-Aware Services in an In-Building Environment J.) achieves enhancement of weak signals by multiplying the input signal by a weight that is positively correlated with fast time; advance normalization (Rov ň akova J, kocur D.Weak signal enhancement in radar signal processing [ C ]//20th International Conference Radioelektronika 2010.IEEE,2010:1-4.) "search for maximum values and normalize the interval signal" is performed continuously from front to back in rapid time order; however, the existing methods have defects, and in some scenes, such as static human breath detection, when clutter energy is higher than target breath signal energy and is located behind a target signal, the two methods can cause deterioration of signal-clutter ratio due to the fact that the two methods adopt the assumption that a long-distance target echo signal is weak; 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): 122-127) adaptively enhances a signal with small energy, and when applied to radar weak signal enhancement, it is not only affected by the selection of the energy window length, but also easily amplifies a non-target signal portion, and it is difficult to enhance a 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, so as to solve the technical problems that the conventional radar signal enhancement method is easily influenced by the relative positions of clutter and target signals or easily causes a non-target signal part method.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the invention provides a radar signal enhancement method, which comprises the following steps:
determining the number N of local signal segments LM A width w; the local signal section is a signal section containing local peak values;
according to the number N of the determined local signal segments LM The width w is used for recursively searching local peaks in the radar signals to be enhanced, and marking signal segments containing the local peaks to obtain marked signal segments;
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 signals by adopting local peaks in the marked signal segments to obtain enhanced radar signals.
Further, the process of determining the number and width of the local signal segments is as follows:
determining the number of local signal segments according to the number of targets and the number of non-target scatterers estimated in the actual acquisition environment of the radar signal to be enhanced;
the width of the local signal segment is determined based on the radar pulse width reflected by the target.
Further, the number of the local signal segments is the sum of the number of the targets and the number of the non-target scatterers estimated in the actual acquisition environment of the radar signal to be enhanced.
Further, according to the determined number N of the local signal segments LM And a width w, 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, wherein the method comprises the following steps of:
s1, initializing the number P=0 of marked signal segments containing local peaks; that is, the number of marked mark signal segments p=0;
s2, if the number P of marked signal segments and the number N of determined local signal segments are marked LM If the same, returning the marked mark signal segment, and ending S2; otherwise, turning to S3;
s3, enabling P=P+1, and searching a mode maximum value of the radar signal in an unlabeled part of the radar signal to be enhanced; marking the unmarked part of the radar signal to be enhanced by taking the signal point corresponding to the currently searched mode maximum value as the center according to the determined width w of the local signal segment to obtain a current marked signal segment; wherein the starting position of the current marking signal section is recorded asThe end position is marked->
S4, if P=1, the current marking signal section is obtained, and then the process is directly transferred to S2;
s5, if the number p of the marked mark signal segments is any, the following is satisfied: p is more than or equal to 1 and less than or equal to P-1; and the current starting position of the marked signal section is recorded asThe end position is marked->The method meets the following conditions: />And is also provided withThen go to S2;
wherein,a start position of a p-th marked signal segment; />An end position of the p-th marked signal segment;
s6, if the number p of the marked mark signal segments is any, the following steps are included: p is more than or equal to 1 and less than or equal to P-1, so thatMake->P=p-1, and go to S3;
s7, if the number p of the marked mark signal segments is any, the following exists: p is more than or equal to 1 and less than or equal to P-1, so thatMake->P=p-1, and go to S3.
Further, according to the marked signal segment, the radar signal to be enhanced is segmented, and the segmented radar signal is obtained by the following steps:
marking and sequencing the start and stop 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 segmentation mark value of the radar signal to be enhanced to obtain a segmented radar signal.
Further, the expression of the position time sequence of the marker signal segment is:
wherein,the start position time of the q-th marked signal section; />Marking the end position time of the signal segment for the q-th mark;
the expression of the segmentation marker value of the radar signal to be enhanced is:
wherein,a segmentation mark value for the q-th radar signal to be enhanced; />The start position time of the signal segment is marked for the q+1th.
Further, according to the segmentation mark value of the radar signal to be enhanced, segmenting the radar signal to be enhanced to obtain a segmented radar signal; the segmented radar signals have P segments, and the expression of each segmented radar signal is specifically as follows:
…，
…，
wherein,the first section radar signal in the radar signals to be enhanced; />A first point of a first section of radar signal in the radar signal to be enhanced; />The last point of the first section radar signal in the radar signal to be enhanced; />The P-th section radar signal in the radar signals to be enhanced; />The method comprises the steps that a first point of a P-th section radar signal in a radar signal to be enhanced is; h is a b (t end ) Is the last point of the radar signal to be enhanced.
Further, the expression of the enhanced radar signal is:
wherein h is E (t) is an enhanced radar signal;to enhance the first segment of radar signal in the post-signal; max is the maximum operation; and I is 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 segments LM A width w; the local signal section is a signal section containing local peak values;
a marking module for determining the number N of the local signal segments LM The width w is used for recursively searching local peaks in the radar signals to be enhanced, and marking signal segments containing the local peaks to obtain marked signal segments;
the segmentation module is used for segmenting the radar signal to be enhanced according to the marked signal segment to obtain a segmented radar signal;
the normalization enhancement module is used for carrying out normalization processing on the segmented radar signals by adopting local peaks in the marked signal segments to obtain enhanced radar signals.
The invention also provides radar signal enhancement equipment, which comprises a memory, a computer program stored in the memory at one stage of the processor and capable of running 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 is characterized in that a signal segment containing a local peak value is used for recursively searching a corresponding marked signal segment in a radar signal to be enhanced, so that the assumption of weak remote template signals is effectively avoided, and the influence of the relative positions of strong clutter and template signals is avoided; segmenting the radar signal to be enhanced according to the marked signal segment, and carrying out normalization processing on the segmented radar signal to realize enhancement of the weak signal, wherein the radar signals after normalization processing are in the same order of magnitude, so that 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, compared with the existing automatic gain control method, the method can effectively avoid the amplification of too many irrelevant signals and prevent the deterioration of the overall signal-to-noise ratio.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following description of the embodiments or the drawings used in the description of the prior art will make a brief description; it will be apparent to those of ordinary skill in the art that the drawings in the following description are of some embodiments of the invention and that other drawings may be derived from them without undue effort.
FIG. 1 is a flow chart of a radar signal enhancement method according to the present invention;
fig. 2 (a) is a schematic diagram of the two-dimensional signal after removing static background and smoothing, i.e. the radar signal to be enhanced in embodiment 1;
fig. 2 (b) is a schematic diagram of the radar signal to be enhanced in embodiment 1 after being enhanced by the method in embodiment 1;
fig. 2 (c) is a schematic diagram of the radar signal to be enhanced in embodiment 1 after being enhanced by an automatic gain control method;
fig. 2 (d) is a schematic diagram of the radar signal to be enhanced in embodiment 1 after being enhanced by an advanced normal algorithm;
FIG. 3 (a) is a schematic diagram of a single echo signal after removing static background and smoothing, i.e. a radar signal to be enhanced, in embodiment 2;
fig. 3 (b) is a schematic diagram of the radar signal to be enhanced in embodiment 2 after being enhanced by the method in embodiment 2;
fig. 3 (c) is a schematic diagram of the radar signal to be enhanced in embodiment 2 after being enhanced by an automatic gain control method;
fig. 3 (d) is a schematic diagram of the radar signal to be enhanced in embodiment 2 after being enhanced by an advanced normal algorithm.
Detailed Description
In order to make the purposes, technical effects and technical solutions of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention are clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention; it will be apparent that the described embodiments are some of the embodiments of the present invention. Other embodiments, which may be made by those of ordinary skill in the art based on the disclosed embodiments without undue burden, are within the scope of the present invention.
As shown in fig. 1, the invention provides a radar signal enhancement method, which comprises the following steps:
step 1, acquiring an original radar echo signal h of a life detection radar b (t) original radar echo Signal h b (t) as radar signal to be enhanced; determining the number N of local signal segments LM A width w; the local signal section is a signal section containing local peak values; the process of determining the number and the width of the local signal segments is specifically as follows:
determining the number of local signal segments according to the number of targets and the number of non-target scatterers estimated 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 targets estimated in the actual acquisition environment of the radar signal to be enhanced and the number of non-target scatterers; the width of the local signal segment is determined based on the radar pulse width reflected by the target.
Step 2, according to the number N of the determined local signal segments LM The width w is used for recursively searching local peaks in the radar signals to be enhanced, and marking signal segments containing the local peaks to obtain marked signal segments; i.e. in the original radar echo signal h b (t) an unlabeled portion, searching for a modulo maximum, and labeling the modulo maximum position as a signal segment of width w.
The specific process is as follows:
s1, initializing the number P=0 of marked signal segments containing local peaks; that is, the number of marked mark signal segments p=0;
s2, if the number P of marked signal segments and the number N of determined local signal segments are marked LM If the same, returning the marked mark signal segment, and ending S2; otherwise, go to S3.
S3, enabling P=P+1, and searching a mode maximum value of the radar signal in an unlabeled part of the radar signal to be enhanced; marking the unmarked part of the radar signal to be enhanced by taking the signal point corresponding to the currently searched mode maximum value as the center according to the determined width w of the local signal segment to obtain a current marked signal segment; wherein the starting position of the current marking signal section is recorded asThe end position is marked->
Judging whether the newly marked marking signal section is overlapped with the marked marking signal, if so, returning to the step S2, otherwise, returning to the step S3, wherein the specific process is as follows:
s4, if P=1, the current marking signal section is obtained, and then the process is directly transferred to S2; when p=1 indicates that only one segment of the marked signal segment is marked, so that the marked signal segments cannot overlap, the process can directly jump to S2 to determine whether to start the next search for the mark.
S5, if the number p of the marked mark signal segments is any, the following is satisfied: p is more than or equal to 1 and less than or equal to P-1; and the current starting position of the marked signal section is recorded asThe end position is marked->The method meets the following conditions: />And is also provided withThen go to S2; in the step S5, no overlapping phenomenon exists in the marked P-1 marked signal sections; wherein (1)>A start position of a p-th marked signal segment; />Is the end position of the p-th marked signal segment.
S6, if the number p of the marked mark signal segments is any, the following steps are included: p is more than or equal to 1 and less than or equal to P-1, so thatMake->P=p-1, and go to S3; in the step S6, the P-th mark signal segment representing the current mark overlaps with one of the marked P-1 mark signal segments, and the specific overlapping form is: the segment header of the P-th marker signal segment is located within the P-th marker signal segment.
S7, if the number p of the marked mark signal segments is any, the following exists: p is more than or equal to 1 and less than or equal to P-1, so thatMake->P=p-1, and go to S3; in the step S7, the P-th mark signal segment of the current mark and one of the marked P-1 mark signal segments overlap, and the specific overlapping form is: the end of the P-th marker signal segment is located within the P-th marker 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 sorting the start and stop 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:
wherein,the start position time of the q-th marked signal section; />The end position time of the signal segment is marked for the q-th.
Step 32, obtaining a segmentation 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:
wherein,a segmentation mark value for the q-th radar signal to be enhanced; />The start position time of the signal segment is marked for the q+1th.
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 have P segments, and the expression of each segmented radar signal is specifically as follows:
…，
…，
wherein,the first section radar signal in the radar signals to be enhanced; />A first point of a first section of radar signal in the radar signal to be enhanced; />The last point of the first section radar signal in the radar signal to be enhanced; />The P-th section radar signal in the radar signals to be enhanced; />The method comprises the steps that a first point of a P-th section radar signal in a radar signal to be enhanced is; h is a b (t end ) Is the last point of the radar signal to be enhanced.
Suppose that there are 4096 points in the radar signal to be enhanced, i.e. t end =4096; according to step 31, the obtained P marked segment start positionsSpecifically, (100, 200), (320, 400), …, (2000,2400), …, (3800, 4000), respectively; then when q=1, we getAnd get->And so on, the expression of the P-th section radar signal in the radar signals to be enhanced can be obtained.
Step 4, adopting local peaks in the marked signal section to normalize the segmented radar signals to obtain enhanced radar signals; the expression of the enhanced radar signal is as follows:
wherein h is E (t) is an enhanced radar signal;to enhance the first segment of radar signal in the post-signal; max is the maximum operation; and I is 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 segments LM A width w; the local signal section is a signal section containing local peak values;
a marking module for determining the number N of the local signal segments LM And width w, recursively searching for a local part in the radar signal to be enhancedThe peak value is marked, and a signal segment containing the local peak value is marked, so that a marked signal segment is obtained;
the segmentation module is used for segmenting the radar signal to be enhanced according to the marked signal segment to obtain a segmented radar signal;
the normalization enhancement module is used for carrying out normalization processing on the segmented radar signals by adopting local peaks in the marked signal segments to obtain enhanced radar signals.
The invention also provides a radar signal enhancement device, comprising: a processor, a memory, and a computer program stored in the memory and executable on the processor, such as: radar signal enhancement procedure. The steps in the radar signal enhancement method described above are implemented when the processor executes the computer program, for example: determining the number N of local signal segments LM A width w; the local signal section is a signal section containing local peak values; according to the number N of the determined local signal segments LM The width w is used for recursively searching local peaks in the radar signals to be enhanced, and marking signal segments containing the local peaks to obtain marked signal segments; 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 signals by adopting local peaks in the marked signal segments to obtain enhanced radar signals.
Alternatively, the processor may implement functions of each module in the radar signal enhancement device apparatus when executing the computer program, for example: a local signal segment module for determining the number N of local signal segments LM A width w; the local signal section is a signal section containing local peak values; a marking module for determining the number N of the local signal segments LM The width w is used for recursively searching local peaks in the radar signals to be enhanced, and marking signal segments containing the local peaks to obtain marked signal segments; the segmentation module is used for segmenting the radar signal to be enhanced according to the marked signal segment to obtain a segmented radar signal; a normalization enhancement module for using local peaks in the marked signal segment to segmentAnd carrying out normalization processing on the radar signals to obtain enhanced radar signals.
The computer program may be divided into one or more modules/units, which are stored in the memory and executed by the processor to accomplish the present invention, for example. The one or more modules/units may be a series of computer program instruction segments capable of performing specific functions for describing the execution of the computer program in the radar signal enhancement device. For example, the computer program may be divided into a local signal segment module, a marking module, a segmentation module and a normalization enhancement module, where each module specifically functions as follows: a local signal segment module for determining the number N of local signal segments LM A width w; the local signal section is a signal section containing local peak values; a marking module for determining the number N of the local signal segments LM The width w is used for recursively searching local peaks in the radar signals to be enhanced, and marking signal segments containing the local peaks to obtain marked signal segments; the segmentation module is used for segmenting the radar signal to be enhanced according to the marked signal segment to obtain a segmented radar signal; the normalization enhancement module is used for carrying out normalization processing on the segmented radar signals by adopting local peaks in the marked signal segments to obtain enhanced radar signals.
The radar signal enhancement device can be a computing device such as a desktop computer, a notebook computer, a palm computer, a cloud server and the like. The radar signal enhancement device may include, but is not limited to, a processor, a memory. Those skilled in the art will appreciate that the radar signal enhancement device is not limiting and may include more or fewer components than the radar signal enhancement device, or may combine certain components, or different components, e.g., the radar signal enhancement device may also include input-output devices, network access devices, buses, etc.
The processor may be a central processing unit (CentralProcessingUnit, CPU), other general purpose processors, digital signal processors (DigitalSignalProcessor, DSP), application specific integrated circuits (ApplicationSpecificIntegratedCircuit, ASIC), off-the-shelf programmable gate arrays (Field-ProgrammableGateArray, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or the like. The general purpose processor may be a microprocessor or the processor may be any conventional processor or the like that is a control center of the radar signal enhancement device, connecting the various parts of the overall radar signal enhancement device using various interfaces and lines.
The memory may be used to store the computer program and/or modules, and the processor may implement various functions of the radar signal enhancement device by running or executing the computer program 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 (such as a sound playing function, an image playing function, etc.) required for at least one function, and the like; the storage data area may store data (such as audio data, phonebook, etc.) created according to the use of the handset, etc.
In addition, the memory may include high-speed random access memory, and may also include non-volatile memory, such as a hard disk, memory, plug-in hard disk, smart memory card (SmartMediaCard, SMC), secure digital (SecureDigital, SD) card, flash card (FlashCard), at least one magnetic disk storage device, 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 local peak value of the signal is regarded as a possible target and a pulse reflected by a non-target scatterer with higher electromagnetic reflectivity, and then the number of signal segments containing the local peak value of the signal is equal to the sum of the estimated number of possible target and non-target scatterers; in principle, the number of signal segments cannot be too small, otherwise all target echoes may not be covered (enhanced); while not being too large or else too many non-target signals may be enhanced.
Example 1
In example 1, the process of enhancing the echo signal of a life detection radar is taken as an example.
The embodiment 1 provides a radar signal enhancement method, and the enhancement object of the radar signal enhancement method in the 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; thus, when the echo signal of the life detection radar is enhanced, only one of the columns, i.e. one echo, is processed at a time.
The method specifically comprises the following steps:
step 1, acquiring an original radar echo signal of a life detection radar, and removing static background and stable clutter in the original radar echo signal by a linear trend removal method or an exponential averaging method to obtain a radar signal h to be enhanced b (t, τ); wherein t is electromagnetic propagation fast time, and tau is radar receiving slow time; determining the number N of local signal segments LM A width w; the local signal segment is a signal segment containing local peaks.
In this embodiment 1, the electromagnetic propagation is time-discrete fast to t=1, 2, …,4096, and time-discrete slow to τ=1, 2, …,1024; it will be clear to a person skilled in the art that the electromagnetic propagation fast time t and the radar reception slow time τ may take other values; as shown in fig. 2 (a), fig. 2 (a) is a schematic diagram of a two-dimensional signal after removing static background and smoothing, i.e. a radar signal to be enhanced in the embodiment; wherein the radar fast time sampling rate is f s =32 GHz, the slow time effective pulse repetition frequency is 32Hz.
In this embodiment 1, to enhance the display contrast, the radar signal h is to be enhanced b (t, τ) performing an absolute value taking operation before imaging; wherein t is the electromagnetic propagation fast time, and each electromagnetic propagation fast time unit isThrough a distance conversion formulaObtaining the distance between the target and the radar; wherein c is the propagation speed of electromagnetic waves; τ is the slow time of radar reception in lanes, one is the occurrence of radar and the reception of an echo, represented as a column in a two-dimensional matrix.
In embodiment 1, the distance between the detected person (target) and the radar is about 1.5m, and the distance conversion formula is usedThe target weak respiratory signal is calculated to be positioned on the radar signal h to be enhanced b Row 302 of (t, τ) and its vicinity; as can be seen from fig. 2 (a), there is a signal of approximately periodic variation in brightness in the vicinity of 320 lines, i.e., a solid line box region of fig. 2 (a); a non-stationary clutter region with overall wavy brightness, namely a dashed line frame region in fig. 2 (a), exists below the clutter region; wherein the larger energy is concentrated between 280-380 rows and 600-680 columns, i.e. the area of the dash-dot frame of fig. 2 (a).
In the embodiment 1, the number of local signal segments is determined 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; determining the width of a local signal section according to the radar pulse width reflected by the target and the thickness of the chest of the human body; setting the number N of the local signal segments LM =6, i.e. the total number of targets and clutter is considered to be no more than 6 in a single echo; setting the width of the local signal segment to w=20; it will be clear to a person skilled in the art that the number of local signal segments N LM And the width w may take other values.
Step 2, according to the number N of the determined local signal segments LM And width w, at radar signal h to be enhanced b (t, τ), τ=1, 2, …,1024 recursively finds local peaks and marks the signal segments containing the local peaks, resulting in marked signal segments.
The specific process is as follows:
s1, initializing the number P=0 of marked signal segments containing local peaks; that is, the number of marked mark signal segments p=0;
s2, if the number P of marked signal segments and the number N of determined local signal segments are marked LM Identical, i.e. p=n LM The method comprises the steps of carrying out a first treatment on the surface of the Or to be enhanced by radar signal h b (t, τ) are marked, then return marked mark signal segment, end S2; otherwise, go to S3.
S3, enabling P=P+1, and searching a mode maximum value of the radar signal in an unlabeled part of the radar signal to be enhanced; marking the unmarked part of the radar signal to be enhanced by taking the signal point corresponding to the currently searched mode maximum value as the center according to the determined width w of the local signal segment to obtain a current marked signal segment; wherein the starting position of the current marking signal section is recorded asThe end position is marked->Wherein (1)>
Judging whether the newly marked marking signal section is overlapped with the marked marking signal, if so, returning to the step S2, otherwise, returning to the step S3, wherein the specific process is as follows:
and S4, if P=1, directly transferring to S2 after acquiring the current marking signal segment.
S5, if the number p of the marked mark signal segments is any, the following is satisfied: p is more than or equal to 1 and less than or equal to P-1; and the current starting position of the marked signal section is recorded asThe end position is marked->The method meets the following conditions: />And is also provided withThen go to S2;
wherein,a start position of a p-th marked signal segment; />An end position of the p-th marked signal segment;
s6, if the number p of the marked mark signal segments is any, the following steps are included: p is more than or equal to 1 and less than or equal to P-1, so thatMake->P=p-1, and go to S3;
s7, if the number p of the marked mark signal segments is any, the following exists: p is more than or equal to 1 and less than or equal to P-1, so thatMake->P=p-1, and go to S3.
Step 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 sorting the start and stop 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:
wherein,the start position time of the q-th marked signal section; />The end position time of the signal segment is marked for the q-th.
Step 32, obtaining a segmentation 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:
wherein,a segmentation mark value for the q-th radar signal to be enhanced; />The start position time of the signal segment is marked for the q+1th. />
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 have P segments, and the expression of each segmented radar signal is specifically as follows:
…，
…，
wherein, among them,a first section of radar signals in radar signals to be enhanced of the life detection radar;a first point of a first section of radar signal in the radar signal to be enhanced of the life detection radar;the last point of the first section of radar signal in the radar signal to be enhanced for the life detection radar; />The P-th section radar signal in the radar signals to be enhanced of the life detection radar; />A P-th section radar signal first point in a radar signal to be enhanced of a life detection radar; h is a b (t end τ) is the last point of the radar signal to be enhanced for the sounding radar.
Step 4, adopting local peaks in the marked signal section to normalize the segmented radar signals to obtain enhanced radar signals; the expression of the enhanced radar signal is as follows:
wherein h is E (t, τ) is an enhanced radar signal for a life-sounding radar;a first-segment radar signal in the enhanced signal for the life detection radar; max is the maximum operation; and I is modulo operation.
Example 2
Embodiment 2 is basically the same as embodiment 1 in principle, except that the radar signal to be enhanced in embodiment 2 is a single echo; wherein the single echo is the 315 th column of the two-dimensional signal in FIG. 2 (a), i.e. h b (t, 315) forming the clutter energy concentration range of fig. 3 (a) as observed at 643 th fast time cell, which is the clutter energy maximum in the whole echo, i.e. the dashed box area in fig. 3 (a); the 317 th fast time unit is the maximum value of the amplitude of the target signal, that is, the solid line box area in fig. 3 (a) is the range in which the target signal is concentrated, and the energy is far less than the strong clutter; the specific enhancement process is substantially the same as the steps of embodiment 1, and will not be described here.
Test results:
fig. 2 (b) is a schematic diagram of a radar signal to be enhanced by the method described in embodiment 1, and fig. 3 (b) is a schematic diagram of a radar signal to be 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 excessively amplified.
In the embodiment 1 and the embodiment 2 of the present invention, the conventional advanced normalization and automatic gain control methods are adopted as comparison methods, and the enhancement effects on the two-dimensional signal are shown in fig. 2 (c) and fig. 2 (d), and the enhancement effects on the single echo are shown in fig. 3 (c) and fig. 3 (d), respectively.
As can be seen from fig. 2 (c), fig. 2 (d), fig. 3 (c) and fig. 3 (d), the principle of advanced normalization determines that the algorithm is not suitable for enhancing the signal with clutter behind the target; for the signals in embodiments 1 and 2 of the present invention, the existing enhancement method cannot effectively enhance the signal above the strong clutter, and obviously amplifies the irrelevant signal after the clutter; the sliding window effect of the automatic gain control makes the automatic gain control easy to amplify irrelevant signals, and has defects when the automatic gain control is applied to the enhancement of ground penetrating radar signals.
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 because the signal gain is calculated based on a sliding window with a certain width, the small amplitude signal of the target-clutter interval is greatly enhanced, so that the clutter-target interval is not obvious, and the clutter-target interval is difficult to distinguish; and unlike the other two methods, the automatic gain control does not automatically normalize the amplitudes of the different echoes to the same range, so that the energy of the final enhanced B-scan signal is still concentrated at the clutter location of a few echoes.
According to the method for enhancing the radar weak signal, firstly, the number and the width of local peak segments of the signal are set according to the number of possible targets and clutter, radar and target characteristics and other priori; recursively searching signal peaks in the echo until the number of marked peak segments meets a preset value or the signals in the echo are marked completely; finally normalizing signals between every two adjacent local peaks; the relative amplitude between the target signal and the clutter can be enhanced in a targeted manner, and the aim of improving the overall signal-to-noise ratio is fulfilled.
The above embodiment is only one of the implementation manners capable of implementing the technical solution of the present invention, and the scope of the claimed invention is not limited to the embodiment, but also includes any changes, substitutions and other implementation manners easily recognized by those skilled in the art within the technical scope of the present invention.
Claims (7)
1. A method of radar signal enhancement, comprising the steps of:
determining the number N of local signal segments LM A width w; the local signal section is a signal section containing local peak values;
according to the determinationNumber of partial signal segments N LM The width w is used for recursively searching local peaks in the radar signals to be enhanced, and marking signal segments containing the local peaks to obtain marked signal segments;
segmenting the radar signal to be enhanced according to the marked signal segment to obtain a segmented radar signal;
carrying out normalization processing on the segmented radar signals by adopting local peaks in the marked signal segments to obtain enhanced radar signals;
the process for determining the number and the width of the local signal segments comprises the following steps:
determining the number of local signal segments according to the number of targets and the number of non-target scatterers estimated 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 a target;
according to the number N of the determined local signal segments LM And a width w, 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, wherein the method comprises the following steps of:
s1, initializing the number P=0 of marked signal segments containing local peaks; that is, the number of marked mark signal segments p=0;
s2, if the number P of marked signal segments and the number N of determined local signal segments are marked LM If the same, returning the marked mark signal segment, and ending S2; otherwise, turning to S3;
s3, enabling P=P+1, and searching a mode maximum value of the radar signal in an unlabeled part of the radar signal to be enhanced; marking the unmarked part of the radar signal to be enhanced by taking the signal point corresponding to the currently searched mode maximum value as the center according to the determined width w of the local signal segment to obtain a current marked signal segment; wherein the starting position of the current marking signal section is recorded asThe end position is marked->
S4, if P=1, the current marking signal section is obtained, and then the process is directly transferred to S2;
s5, if the number p of the marked mark signal segments is any, the following is satisfied: p is more than or equal to 1 and less than or equal to P-1; and the current starting position of the marked signal section is recorded asThe end position is marked->The method meets the following conditions: />And is also provided withThen go to S2;
wherein,a start position of a p-th marked signal segment; />An end position of the p-th marked signal segment;
s6, if the number p of the marked mark signal segments is any, the following steps are included: p is more than or equal to 1 and less than or equal to P-1, so thatMake->P=p-1, and go to S3;
s7, if the number p of the marked mark signal segments is any, the following exists: p is more than or equal to 1 and less than or equal to P-1, so thatMake->P=p-1, and go to S3;
according to the marked signal segment, segmenting the radar signal to be enhanced, and obtaining a segmented radar signal, wherein the process is as follows:
marking and sequencing the start and stop 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 segmentation mark value of the radar signal to be enhanced to obtain a segmented radar signal.
2. The method of claim 1, wherein the number of local signal segments is a sum of the number of targets and the number of non-target scatterers estimated in an actual acquisition environment of the radar signal to be enhanced.
3. The radar signal enhancement method according to claim 1, wherein the expression of the position time series of the marker signal segment is:
wherein,the start position time of the q-th marked signal section; />Marking the end position time of the signal segment for the q-th mark;
the expression of the segmentation marker value of the radar signal to be enhanced is:
wherein,a segmentation mark value for the q-th radar signal to be enhanced; />The start position time of the signal segment is marked for the q+1th.
4. A radar signal enhancement method according to claim 3, wherein the radar signal to be enhanced is segmented according to a segmentation marker value of the radar signal to be enhanced, so as to obtain a segmented radar signal; the segmented radar signals have P segments, and the expression of each segmented radar signal is specifically as follows:
…，
…，
wherein,the first section radar signal in the radar signals to be enhanced; />A first point of a first section of radar signal in the radar signal to be enhanced; />The last point of the first section radar signal in the radar signal to be enhanced;the P-th section radar signal in the radar signals to be enhanced; />The method comprises the steps that a first point of a P-th section radar signal in a radar signal to be enhanced is; h is a b (t end ) Is the last point of the radar signal to be enhanced.
5. The method of claim 4, wherein the expression of the enhanced radar signal is:
wherein h is E (t) is an enhanced radar signal;to enhance the first segment of radar signal in the post-signal; max is the maximum valueOperating; and I is modulo operation.
6. A radar signal enhancement system, comprising:
a local signal segment module for determining the number N of local signal segments LM A width w; the local signal section is a signal section containing local peak values;
a marking module for determining the number N of the local signal segments LM The width w is used for recursively searching local peaks in the radar signals to be enhanced, and marking signal segments containing the local peaks to obtain marked signal segments;
the segmentation module is used for segmenting the radar signal to be enhanced according to the marked signal segment to obtain a segmented radar signal;
the normalization enhancement module is used for carrying out normalization processing on the segmented radar signals by adopting local peaks in the marked signal segments to obtain enhanced radar signals;
the process for determining the number and the width of the local signal segments comprises the following steps:
determining the number of local signal segments according to the number of targets and the number of non-target scatterers estimated 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 a target;
according to the number N of the determined local signal segments LM And a width w, 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, wherein the method comprises the following steps of:
s1, initializing the number P=0 of marked signal segments containing local peaks; that is, the number of marked mark signal segments p=0;
s2, if the number P of marked signal segments and the number N of determined local signal segments are marked LM If the same, returning the marked mark signal segment, and ending S2; otherwise, turning to S3;
s3, let P=P+1, in the untagged part of the radar signal to be enhanced, searching the mode most of the radar signalA large value; marking the unmarked part of the radar signal to be enhanced by taking the signal point corresponding to the currently searched mode maximum value as the center according to the determined width w of the local signal segment to obtain a current marked signal segment; wherein the starting position of the current marking signal section is recorded asThe end position is marked->
S4, if P=1, the current marking signal section is obtained, and then the process is directly transferred to S2;
s5, if the number p of the marked mark signal segments is any, the following is satisfied: p is more than or equal to 1 and less than or equal to P-1; and the current starting position of the marked signal section is recorded asThe end position is marked->The method meets the following conditions: />And is also provided withThen go to S2;
wherein,a start position of a p-th marked signal segment; />An end position of the p-th marked signal segment;
s6, if the number p of the marked mark signal segments is any, the following steps are included: p is more than or equal to 1 and less than or equal to P-1, so thatMake->P=p-1, and go to S3;
s7, if the number p of the marked mark signal segments is any, the following exists: p is more than or equal to 1 and less than or equal to P-1, so thatMake->P=p-1, and go to S3;
according to the marked signal segment, segmenting the radar signal to be enhanced, and obtaining a segmented radar signal, wherein the process is as follows:
marking and sequencing the start and stop 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 segmentation mark value of the radar signal to be enhanced to obtain a segmented radar signal.
7. A radar signal enhancement device comprising a memory, a computer program stored in said memory at a processor level and executable on said processor, wherein said processor implements the radar signal enhancement method according to any one of claims 1-5 when said computer program is executed by said processor.
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