JP3567906B2 - Radar signal processor - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a radar signal processing device that emits radio waves from an antenna, receives a reflected wave from an irradiated target, detects the presence of the target, and is used in a radar device for measuring the position of the target. More specifically, the present invention relates to a radar signal processing device for classifying a reflected object from a Doppler frequency component of a reflected signal from a target.
[0002]
[Prior art]
FIG. 6 is a block diagram showing a conventional radar signal processing device. Hereinafter, description will be made based on this drawing.
[0003]
The radar signal processing device 53 includes a detection / tracking system 55 for detecting and tracking the target based on the reflected signal from the target, and a classification processing system 56 for classifying the reflected object based on the Doppler frequency component of the reflected signal. Is used in a coherent pulse Doppler radar apparatus that classifies moving targets based on Doppler frequency components of reflected waves.
[0004]
The operation modes of the radar signal processing device 53 are roughly classified into two modes: a search mode for searching and tracking a target, and a classification mode for supporting classification of a target type by an operator. The procedure up to the target classification is shown below.
[0005]
First, the operator selects the classification target in the search mode, and then changes the operation mode to the classification mode. Subsequently, by adjusting the antenna direction so that the beam direction radiated in the antenna unit 1 becomes the direction of the target to be classified, the distance for performing the classification processing is set to the target position. Then, the result of the above-described classification processing that is continuously output is confirmed, and finally, the target classification is performed by its own judgment. The operation will be described below in the order of the search mode and the classification mode in accordance with the operation procedure up to the target classification.
[0006]
In the search mode, the antenna unit 1 is driven in the azimuth direction according to a predetermined search cycle. When a target exists in the directed beam direction, a reflected signal from the target is input to the transmission / reception unit 2 via the antenna unit 1 and subjected to frequency conversion and phase detection to perform coherent reception I (In-phase), Q The signal is input to the radar signal processing device 53 as (Quadrature) video.
[0007]
The coherent reception I and Q videos are provided inside a radar signal processing device 53 by a detection / tracking system 55 for detecting and tracking a target, and a classification processing system 56 for outputting Doppler information for target classification. Diverged to both systems. The classification processing system 56 does not perform any operationally significant processing in the search mode, and a description thereof will be omitted.
[0008]
The coherent reception I and Q videos input to the detection / tracking system 55 are subjected to MTI (Moving Target Indicator) processing, Doppler filter processing, CFAR (Constant False Alarm Rate) processing and the like in a clutter (unnecessary reflection) suppressing section 57. As a result, the processed video from which unnecessary signals other than the target signal have been removed is output to the display control unit 54 and the target detection / orientation unit 58. The target detecting and locating unit 58 detects the presence or absence of a target by a threshold determination process or the like with respect to the amplitude of the processed video, and locates the target by referring to the antenna direction signal from the antenna unit 1 to determine the target position. The orientation results such as the processed video amplitude are output to the target tracking unit 59 and the display control unit 54.
[0009]
In the target tracking unit 59, the prediction gate indicating the target predicted position range in the current antenna scanning calculated based on the past orientation results obtained by the previous antenna scanning is compared with the target position input this time, The target closest to the prediction center position among the targets in the prediction gate is determined as the tracking target, and the tracking result such as the tracking target position is output to the display control unit 54.
[0010]
The processed video output from the radar signal processing device 53 and the tracking result of the target are displayed on the radar scope 54a of the display control unit 54, so that the operator can know the position of the target from the displayed contents. .
[0011]
Next, the contents and operation of the classification mode will be described. In the classification mode, the beam direction of the antenna unit 1 is directed to the target direction, and in a state where the reflected wave from the target can be continuously received, the target signal is obtained from the coherent reception I video and Q video obtained every radar transmission pulse period. By extracting Doppler frequency components generated by movement in the radar direction, Doppler spectrum display and Doppler hearing sound generation are performed.
[0012]
After determining an arbitrary classification target from among the targets obtained in the search mode, the operator changes the radar operation mode from the search mode to the classification mode by operating the radar control unit 54b of the display control unit 54, and The beam direction of the antenna unit 1 is scanned in the target direction, and the distance for performing the classification process is specified on the radar scope 54a.
[0013]
At this time, a distance gate signal indicating the distance at which the classification processing is performed is output from the radar control unit 54b to the classification processing system 56. The FFT (Fast Fourier Transform) processing unit 68 and the Doppler hearing sound extraction unit 61 of the classification processing system 56 perform FFT processing for Doppler spectrum display and Doppler hearing sound for Doppler sound generation for the distance specified by the distance gate signal. And data extraction processing.
[0014]
The spectrum data output from the FFT processing unit 68 is displayed as a spectrum waveform as shown in FIG. 7 on the spectrum display unit 54c of the display control unit 54. 7, the horizontal axis represents the Doppler frequency, and the vertical axis represents the target received signal power. When the number of FFT points is n, the frequency resolution Δf [Hz] of the Doppler frequency is:
Δf = PRF / n where PRF is the transmission pulse repetition frequency [Hz]
Thus, n spectrum data strings for each Doppler frequency Δf are obtained.
[0015]
The frequency resolution Δf at the time of the FFT processing in the classification processing system 56 needs to have a sufficient resolution so that the operator can visually classify from the spectrum display. Therefore, in the normal case, the frequency resolution at the time of the FFT processing of the classification processing system 56 is larger than the frequency resolution of the Doppler filter used in the clutter suppression unit 57 of the detection / tracking system 55 (the value of Δf, as shown in FIG. 8). Becomes smaller).
[0016]
If the target moving speed in the radar direction is Vr [m / s], the Doppler frequency fp [Hz] at which the received signal power has a peak value is generally given by the following equation.
fp = 2Vr / λ where λ is the radar transmission wavelength [m]
[0017]
When the target has another speed component in the radar direction other than the target moving speed component, the spectrum is displayed even at a Doppler frequency other than the above-mentioned Doppler frequency fp. For example, when a vehicle moving by wheels is observed by the radar apparatus, the Doppler frequency of the reflected wave from the wheels spreads in a range of 0 to 2 Vr in principle. Therefore, it is possible to classify the targets based on the difference in the spectrum shape for each target.
[0018]
The Doppler hearing sound extraction unit 61 extracts Doppler hearing sound data from coherent reception I-video or Q-video input from the transmission / reception unit 2 for each radar transmission pulse period, and outputs the data to the display control unit 54. The audible sound data is converted into an audible sound signal which is an analog signal by a audible sound conversion unit 54d of the display control unit 54, and is generated from the speaker 62 as Doppler audible sound.
[0019]
Even if the same target is being categorized, the Doppler spectrum display and the Doppler listening sound output from the radar signal processing device 53 fluctuate variously in accordance with changes in the moving direction and speed of the target. Therefore, in the radar signal processing device 53, the operator classifies the target from the continuously obtained spectrum display and Doppler hearing sound based on his / her own visual and auditory memory.
[0020]
[Problems to be solved by the invention]
However, the radar signal processing device 53 has the following problems.
[0021]
The first problem is that other targets cannot be tracked during target classification. The reason is that the operator needs to keep a state in which a received signal from the target can be continuously obtained until the classification is completed because the operator classifies the target by his / her own visual and auditory senses. This is because the beam direction needs to be directed to the target direction of the classification target.
[0022]
The second problem is that the labor and skill of the operator at the time of target classification are increased. The reason is as follows. Although it has a function of providing Doppler spectrum and Doppler hearing sound to the operator as information contributing to classification, the Doppler spectrum and Doppler hearing sound vary from moment to moment according to changes in the moving direction and speed of the target. Change. For this reason, operators are sufficiently familiar with reading spectrum displays and distinguishing Doppler listening sounds, and classification is difficult unless they have prior knowledge of characteristic spectrum displays and Doppler listening sounds for each type of target to be classified. Because it becomes.
[0023]
On the other hand, a target classifying apparatus for automatically classifying targets without relying on the skill level of the operator is disclosed in, for example, Japanese Patent Application Laid-Open No. 7-92259. This target classification device extracts a feature from information acquired by a Doppler radar, compares the extracted feature with a feature already possessed by the classification target, and performs a classification process based on the matching ratio.
[0024]
However, this kind of target classification apparatus has the following problems.
[0025]
The first problem is that it is difficult to track other targets during target classification. The reason for this is that nothing has been devised for the Doppler spectrum that changes for each antenna scan according to the moving direction and speed of the target, so that the received signal from the target is continuously output until the classification is completed. This is because it is necessary to keep the obtained state, so that it is necessary to direct the beam direction of the antenna to the target direction of the classification target.
[0026]
The second problem is that it is difficult to execute target classification quickly and accurately. The reason is that the database for collation becomes enormous because the Doppler spectrum, which changes every moment according to the change of the moving direction and speed of the target, is enormous. Because it becomes long. Therefore, the above-mentioned radar signal processing device 53 is used at an actual site.
[0027]
[Object of the invention]
Therefore, an object of the present invention is to provide a radar signal processing device capable of performing target classification in parallel with search and tracking processing. Another object of the present invention is to reduce the labor and skill of an operator required for target classification.
[0028]
[Means for Solving the Problems]
The radar signal processing device according to the present invention includes a detection / tracking system that detects and tracks the target based on a reflection signal from the target, and a classification processing system that classifies a reflection object based on a Doppler frequency component of the reflection signal. It is provided with. The classification processing system inputs a target position from the detection / tracking system, and outputs a Doppler spectrum at the position as a target spectrum (for example, an FFT processing unit); The Doppler frequency is relativized by dividing by the peak power and the Doppler frequency, and a spectrum normalizing unit that outputs the relativized spectrum as a normalized spectrum converted into a predetermined format, based on the normalized spectrum A target classification processing unit for classifying the targets (claim 1);
[0029]
The classification processing system may further include an unnecessary signal removing unit that removes an unnecessary component corresponding to a noise level from the target spectrum and outputs the signal to the spectrum normalizing unit.
[0030]
The classification processing system further includes a spectrum averaging unit that averages a plurality of standardized spectra for the same target input by a plurality of antenna scans and outputs an average value as an averaged spectrum. The unit may classify the target based on the averaged spectrum (claim 3).
[0031]
The spectrum averaging unit obtains an average value between the normalized spectrum in the current antenna scanning and the averaged spectrum held in the spectrum memory, and holds the average value in the spectrum memory as an averaged spectrum. The information may be output to the target classification processing unit (claim 4).
[0032]
The spectrum averaging unit obtains, for each antenna scan, the integrated value of the normalized power for each normalized Doppler frequency constituting the normalized spectrum, and the number of effective scans in which the normalized power is an effective value other than 0, By dividing the integral value by the number of effective scans, an average value of the normalized power for each normalized Doppler frequency is calculated, and the average value is output to the target classification processing unit as an averaged spectrum. 5).
[0033]
The detection and tracking system specifies a Doppler filter group consisting of multiple Doppler filters that extract and output only a signal with a specific Doppler frequency from the reflected signals, and the level of each Doppler filter output signal is specified. A clutter extraction unit that determines that the level is greater than or equal to the predetermined length and that the range is greater than or equal to the predetermined length, and outputs a determination result of the presence or absence of clutter for each Doppler filter at the target position to the classification processing system. Good (claim 6).
[0034]
The spectrum normalizing unit may calculate a target Doppler frequency range using Doppler filter information in the detection / tracking system, and detect a peak power of the target spectrum from the Doppler frequency range (claim 7). .
[0035]
The target classification processing unit may include a database including a standardized spectrum for each type of the reflection object, and may classify the target by obtaining a degree of coincidence between the averaged spectrum and the database (claim 8).
[0036]
The target classification processing unit has a database constructed for each target aspect angle indicating an angle between the moving direction of the target and the radar direction, inputs a target position and a target moving direction from a detection / tracking system, and The aspect angle may be calculated, and the target may be classified using a database corresponding to the calculated aspect angle (claim 9).
[0037]
The target classification processing unit calculates a target RCS based on the target position and the target received signal amplitude input from the detection / tracking system, and calculates a target RCS based on the target RCS and the target moving speed input from the detection / tracking system. May be narrowed down, and the target may be classified only for the narrowed down type (claim 10).
[0038]
In other words, the radar signal processing device according to the present invention has means for performing target classification processing while searching for and tracking a target. Specifically, an FFT process is performed on the received video signal input in each radar transmission pulse repetition period in the classification processing system, and detection / detection is performed for each antenna scan from the obtained target Doppler spectrum. FFT processing unit that extracts the Doppler spectrum of the target being tracked based on the tracking result of the target obtained by the tracking system, and unnecessary signal removal unit that removes spectrum components unnecessary for classification processing from the extracted target spectrum. From the target spectrum from which unnecessary spectrum components have been removed into a spectrum relative to the peak of the spectrum, which is less dependent on the moving direction and speed of the target, and further standardized to a format suitable for subsequent classification processing And a standardized spectrum for the same tracking target over the antenna scan. Spectrum averaging unit for disproportionation, and has a target classification processing unit that performs classification processing of the target from the averaged spectrum.
[0039]
Next, the operation of the radar signal processing device according to the present invention will be described.
[0040]
In order to execute the target search / tracking processing and the classification processing in parallel, Doppler spectrum data on the target to be identified can be obtained only intermittently. Therefore, the absolute Doppler spectrum of the target to be identified, which has been output in the conventional radar signal processing device, varies in various ways due to changes in speed and moving direction due to the time transition of the target.
[0041]
In the radar signal processing device according to the present invention, in order to be less susceptible to a change in the moving state of the target caused by a time change, a spectrum normalizing unit obtains a relative relationship with respect to a peak value of the spectrum. Is converted into a spectrum standardized in a format suitable for classification processing (hereinafter, referred to as "normalized spectrum"). Further, by averaging the normalized spectrum over the antenna scanning by the spectrum averaging unit, the spectrum display waveform is visually averaged by the operator in a conventional radar signal processing apparatus.
[0042]
Specifically, first, the FFT processing unit extracts only the FFT result (hereinafter, referred to as “target spectrum”) for the tracking target distance and direction specified from the detection / tracking system. Subsequently, an unnecessary signal removing unit removes, from the target spectrum, a spectrum component unnecessary for the classification process. Subsequently, in the spectrum normalizing unit, the target spectrum from which the unnecessary components have been removed is converted into a spectrum relative to the peak value, and then converted into a standardized spectrum suitable for classification processing.
[0043]
The standardized spectrum is output to the target classification processing unit as a spectrum averaged over a plurality of antenna scans in the spectrum averaging unit (hereinafter, referred to as “averaged spectrum”). This averaged spectrum is subjected to classification processing by the target classification processing unit, and is further output to the display control unit.
[0044]
According to the above-described operation, the radar signal processing device according to the present invention allows the antenna to be driven to search and track another target, and to perform classification processing of the target being tracked. In addition, since the standardized spectrum, the averaged spectrum, and the classification processing result are displayed on the display control unit, the target classification can be performed more easily than the conventional radar signal processing device.
[0045]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described in detail with reference to the drawings.
[0046]
FIG. 1 is a block diagram showing a first embodiment of a radar signal processing device according to the present invention. Hereinafter, description will be made based on this drawing.
[0047]
The radar signal processing device 3 according to the present embodiment includes a detection / tracking system 5 that detects and tracks a target based on a reflected signal from the target, and a classification processing system that classifies a reflected object based on a Doppler frequency component of the reflected signal. 6 is provided. The classification processing system 6 inputs a target position from the detection / tracking system 5, and outputs an Doppler spectrum at the position as a target spectrum, an FFT processing unit 18 as a target spectrum output unit, and a noise level equivalent to a noise level from the target spectrum. An unnecessary signal removing unit 19 for removing unnecessary components and a power and a Doppler frequency constituting a target spectrum after removing the unnecessary components are relativized by dividing by a peak power and the Doppler frequency, and the relativized spectrum is obtained. A spectrum normalizing unit 20 that outputs a standardized spectrum converted into a predetermined format, and a plurality of standardized spectra for the same target input by a plurality of antenna scans are averaged, and the average value is used as an averaged spectrum. Output spectrum flat A unit 21, and a target classification processor 22 for classification processing target based on the average of the spectrum.
[0048]
In the radar signal processing device 3 of the present embodiment, the classification process can be performed even in an operation mode corresponding to the search mode of the conventional radar signal processing device (hereinafter, also referred to as “search mode”). Since this is an operational feature, only the part relating to the search mode will be described here. It is needless to say that if the radar signal processing device 3 is provided with a portion related to the generation of Doppler hearing sound of the conventional radar signal device, the function of the classification mode in the conventional radar signal device will be provided.
[0049]
The antenna unit 1 and the transmission / reception unit 2 may be the same as the conventional antenna unit 1 and the transmission / reception unit 2 shown in FIG. 6, respectively, and thus description thereof will be omitted.
[0050]
The radar signal processing device 3 is roughly divided into a detection / tracking system 5 and a classification processing system 6 as in the case of the conventional radar signal processing device. The detection / tracking system 5 includes a clutter suppression unit 7, a target detection / locating unit 8, and a target tracking unit 9 similar to those of the conventional radar processing apparatus, and also extracts a Doppler frequency at which clutter exists to the classification processing system 6. It comprises a clutter extraction unit 10 for transmitting. Hereinafter, the function of each unit constituting the detection / tracking system 5 will be described.
[0051]
The clutter suppression unit 7 includes a canceller 11, a detection system Doppler filter group 12, a CFAR processor 13, a maximum value selector 14, and the like. Except for a function of outputting the maximum signal filter number to the target detection / location unit 8, It has basically the same function as the conventional clutter suppressing section 57 of FIG. The canceller 11 suppresses fixed clutter.
[0052]
The detection system Doppler filter group 12 includes a plurality of Doppler filters arranged on a Doppler frequency axis at a frequency interval substantially corresponding to the pass bandwidth of each filter. The Doppler filter separates a target signal and a clutter on the Doppler frequency axis and, in order to improve the S / N ratio of the target signal, obtains a specific signal from coherent reception I and Q video data that are continuous for each radar transmission pulse period. Only signals having a Doppler frequency are intensively extracted.
[0053]
The CFAR processor 13 performs a CFAR (constant false alarm rate) process for each filter output of the detection system Doppler filter group 12 in order to keep the false alarm rate at the time of target detection processing in the subsequent stage low and constant.
[0054]
The maximum value selector 14 selects and outputs the signal having the maximum amplitude from among the filter outputs after the CFAR processing having the same radar processing range, and also performs the Doppler filter number (hereinafter, referred to as “maximum signal”) having the maximum signal. Filter number ").
[0055]
The target detecting / locating unit 8 has the maximum signal filter number (hereinafter, referred to as “target detecting filter number”) when detecting and locating the target, in addition to the functions of the conventional target detecting / locating unit 58 in FIG. And a function of outputting the target distance to the clutter extracting unit 10 by incorporating the target distance into the target tracking unit 9 and a target position, a received signal amplitude, and the like.
[0056]
Similar to the conventional target tracking unit 59 in FIG. 6, the target tracking unit 9 includes a prediction gate that is a target prediction position range in the current antenna scanning calculated based on the past orientation results obtained by the previous antenna scanning. In addition to the function of comparing the target position input this time and determining the target in the prediction gate as the tracking target, it is used for calculating the target number of the tracking target, the target position, the target detection filter number, and the prediction gate. It has a function of outputting the target speed, the target movement direction, and the like to the classification processing system 6 and the display control unit 4 as tracking results.
[0057]
The clutter extraction unit 10 includes a level determiner 15, a range determiner 16, a clutter filter selector 17, and the like, and performs classification processing on the filter numbers of the detection system Doppler filter groups 12 in which the clutter exists at the distance where the target is detected. Output to system 6.
[0058]
Here, the level determiner 15 performs a determination based on a threshold for detecting the presence or absence of clutter with respect to the level of the signal output from the detection system Doppler filter group 12 to each filter. And outputs a binary value indicating whether the threshold level has been exceeded to the range determiner 16 in units of processing range bins of the radar apparatus as hit detection signals corresponding to "hit" and "no hit", respectively.
[0059]
Further, the range determiner 16 makes a threshold determination on the length of the hit detection signal in the range direction, generally using the fact that the clutter has a spread in the range direction, and exceeds the predetermined threshold length. The binary value of whether or not the data is output to the clutter filter selector 17 as a clutter detection signal corresponding to “clutter present” and “clutter not present”, respectively.
[0060]
The clutter filter selector 17 samples the clutter detection signal input from the range determiner 16 at the target distance input from the target detection / orientation unit 8, and outputs a clutter detection signal at the target distance for each detection system Doppler filter. The presence / absence of the clutter detection signal is checked, and the Doppler filter number (hereinafter, referred to as “clutter filter number”) of the detection system whose clutter detection signal is “clutter present” is output to the classification processing system 6.
[0061]
Next, the configuration and functions of the classification processing system 6 will be described. The classification processing system 6 includes, in addition to the FFT processing unit 18, an unnecessary signal removing unit 19, a spectrum normalizing unit 20, a spectrum averaging unit 21, and a target classification processing unit 22, which are not included in the conventional classification processing system 56 of FIG. And so on. Hereinafter, the function of each unit of the classification processing system 6 will be described.
[0062]
The FFT processing unit 18 has an FFT calculation function equal to or more than that of the conventional FFT processing unit 68 of FIG. 6 and a Doppler spectrum of a target position input from the target tracking unit 9 from the temporarily stored FFT processing results. It has a function of extracting a certain target spectrum and outputting it to the unnecessary signal removing unit 19 and the display control unit 4.
[0063]
The unnecessary signal removing unit 19 inputs a category effective filter range, which is a range of the Doppler frequency of the target spectrum for which the classification process is valid, designated by the display control unit 4 by the operator, and enters the category effective filter range. Has a function of extracting only target spectrum data and a function of removing unnecessary signals such as noise and clutter, and includes a noise remover 23 and a clutter remover 24. Here, normally, the Doppler filter of the classification processing system 6 in which the Doppler frequency in FIG. 7 where the influence of the fixed clutter is great near 0 and near the radar transmission pulse repetition frequency (PRF) is excluded from the classification effective filter range.
[0064]
Further, the noise remover 23 sets the spectrum data corresponding to the noise level in the target spectrum in the specified range to “0” and outputs the spectrum data to the clutter remover 24. The clutter remover 24 sets the input target spectrum data to “0” for the Doppler frequency corresponding to the pass frequency band of the clutter filter number input from the clutter extraction unit 10.
[0065]
The spectrum normalizing unit 20 standardizes a Doppler spectrum that fluctuates variously according to a change in a moving direction and a speed of a target into a format that can be processed by the target classification processing unit 22 (hereinafter, referred to as a “normalized spectrum”). , And has a function of outputting a peak detector 25 and a normalization calculator 26.
[0066]
Here, the peak detector 25 obtains the peak value of the power and the Doppler frequency at that time from the input target spectrum data in the Doppler frequency range corresponding to the target detection filter number input from the target tracking unit 9, and obtains the target spectrum. At the same time, the data is output to the normalization calculator 26.
[0067]
Further, the normalization calculator 26 divides the power and Doppler frequency of the target spectrum by the peak power input from the peak detector 26 and the Doppler frequency at that time, respectively, thereby obtaining a spectrum relative to the peak (hereinafter referred to as “the peak power”). The relative spectrum is further converted into a normalized spectrum having a format suitable for the classification process, and output to the spectrum averaging unit 21 and the display control unit 4.
[0068]
The spectrum averaging unit 21 includes a spectrum memory 28 and an average calculator 27, and outputs an averaged spectrum, which is an average spectrum of the normalized spectrum obtained for each antenna scan.
[0069]
Here, the spectrum memory 28 receives a tracking target number from the target tracking unit 9, reads out the averaged spectrum up to the previous antenna scan stored for the target number, and outputs the averaged spectrum to the average calculator 27. And a function of recording the averaged spectrum output by the average calculator 27.
[0070]
The average calculator 27 calculates the average value of the normalized spectrum input from the spectrum normalizing unit 20 and the averaged normalized spectrum up to the previous antenna scan input from the spectrum memory 28. Is output to the spectrum memory 28 and the display control unit 4.
[0071]
Here, in order to make the hardware scale of the spectrum averaging unit 20 as small as possible, the configuration example in which the averaged spectrum of the spectrum memory 28 is overwritten and updated for each antenna scan has been described. However, when the spectrum memory capacity can be increased, Alternatively, a standardized spectrum for each of a plurality of antenna scans in the past may be stored, and an average value may be obtained from the standardized spectrum for the plurality of scans and the standardized spectrum input in the current antenna scan.
[0072]
The target classification processing unit 22 basically performs target classification processing based on the averaged spectrum input from the spectrum averaging unit 21. Here, the target classification processing based on the averaged spectrum may be any method as long as the processing uses a spectrum waveform as an information source. For example, evaluation of the degree of coincidence with typical standardized spectrum data (hereinafter, referred to as “database”) constructed in advance for each target type, and typical statistical analysis results on variance, symmetry, and the like of an averaged spectrum waveform. Comparison with statistical data.
[0073]
The target type having the highest correlation with the database and the certainty degree of the classification result for each target type with respect to the input averaged spectrum, which are obtained by the target classification processing in the target classification processing unit 22, are obtained by the target classification processing result. Is output to the display control unit 4. A function of calculating a target RCS (effective reflection area) from the position of the tracking target input from the target tracking unit 9 and the received signal amplitude and storing the same with the moving speed input from the target tracking unit 9; By adding a function for narrowing down classification target candidates assumed based on the RCS and the moving speed accumulated in the target classification processing unit 22 to the target classification processing unit 22, the efficiency of the classification processing can be improved.
[0074]
The display control unit 4 has basically the same function as the conventional display control unit 54 of FIG. 6, and also has a function of displaying a standardized spectrum, an averaged spectrum, and a classification processing result.
[0075]
Next, the operation of the radar signal processing device 3 of the present embodiment will be described.
[0076]
The received I and Q videos are input from the transmission / reception unit 2 to the radar signal processing device 3 every radar transmission pulse period, and are branched into the detection / tracking system 4 and the classification processing system 5 inside the radar signal processing device 3. You. The operation of the detection / tracking system 4 and the classification processing system 5 will be described below.
[0077]
The detection and tracking system 5 performs detection of a target based on the received I and Q video signals, localization of the detection target, and tracking of the target similarly to the conventional detection and tracking system 55 of FIG. 6, and is superimposed on the target spectrum. A clutter extraction operation for removing moving clutter at the time of classification processing is performed. The classification processing system 6 automatically classifies the types of targets detected and tracked by the detection and tracking system 5.
[0078]
Hereinafter, the operation contents of the detection / tracking system 4 and the classification processing system 5 will be sequentially described along the signal flow.
[0079]
The received I and Q video signals branched and input to the detection / tracking system 4 are input to the clutter suppression unit 7 in the same manner as the conventional detection / tracking system 54 of FIG. 6, and after the fixed clutter component is suppressed by the canceller 11. Are output from the detection system Doppler filter group 12 as video signals separated from each other on the Doppler frequency axis. An output signal from each filter of the detection system Doppler filter group 12 is branched to the CFAR processor 13 side and the clutter extraction unit 10 side. The operation of the detection / tracking system 5 will be described below in accordance with the flow of each branched signal.
[0080]
The signal input to the CFAR processor 13 is subjected to CFAR processing for each filter output in the CFAR processor 13 and output to the maximum value selector 14. The maximum value selector 14 selects, for each range bin processed by the radar, a signal having the maximum amplitude and its filter number (hereinafter, referred to as a “maximum signal filter number”) from the output signals of the respective filters after the CFAR processing. And outputs it to the target detection and orientation unit 8. Here, the former signal having the maximum amplitude is sent to the display control unit 4 as processed video and displayed.
[0081]
The target detecting and locating unit 8 performs target detection and position locating in the same manner as the conventional target detecting and locating unit 58 shown in FIG. 6, and determines the distance and direction (hereinafter, referred to as “located position”) at which the target is detected and located. , And outputs the processed video amplitude and the maximum signal filter number at the location to the target tracking unit 9 and the display control unit 4 as the location results.
[0082]
The orientation result input to the target tracking unit 9 is compared with a prediction gate indicating the target predicted position range in the current scan calculated from the orientation results up to the previous scan, similarly to the processing in the conventional target tracking unit 9 in FIG. Is done. When there are a plurality of orientation results inside the prediction gate, among them, the one having the orientation result with the highest correlation with the target being tracked is determined as the true tracking target.
[0083]
Here, when multi-target tracking is performed, calculation of a prediction gate and correlation processing of tracking are performed for each target number of a tracking target managed by the target tracking unit 9. The target number, the orientation of the tracking target, the target detection filter number at which the tracking target was detected, and the target moving direction and target speed used for calculating the prediction gate are sent to the classification processing system 6 and the display control unit 4 as tracking results. Is output.
[0084]
On the other hand, the signal branched from the detection system Doppler filter group 12 to the clutter extraction unit 10 is subjected to threshold determination for the signal level in the level determiner 15 for each filter output, and exceeds the threshold level. The signal is converted into a binary state signal (hereinafter, referred to as a "hit detection signal"), which is "hit" and a signal below the threshold level is "no hit", and is output to the range determiner 16. Is done.
[0085]
The range determiner 16 performs a threshold determination on the length in the range direction of the hit detection signal for each Doppler filter, and outputs a "hit" signal exceeding a predetermined range length as "clutter" and a predetermined range length. The following "hit" signal and "no hit" signal are output to the clutter filter selector 17 as a binary state signal of "no clutter" (hereinafter referred to as "clutter detection signal").
[0086]
The clutter filter selector 17 checks the state of the clutter detection signal at the target distance based on the target distance signal input from the target detection and orientation unit 8, and detects the detection system Doppler filter in the “clutter existence” state. The filter number of the group 12 is output to the classification processing system 6.
[0087]
Next, the operation of the classification processing system 6 will be described in detail with reference to the drawings. The received I and Q videos input from the transmission / reception unit 2 at every radar transmission pulse period are subjected to the same FFT processing as the conventional FFT processing unit 68 of FIG. 6 in the FFT processing unit 18 and temporarily stored as spectrum data. Only the spectrum data corresponding to the target position input from the target tracking unit 9 (the target spectrum in FIG. 2A) is extracted from the temporarily stored spectrum data, and the unnecessary signal removing unit 19 and Output to the display control unit 4. Since the target spectrum obtained here is raw data directly reflecting the target moving speed in the radar direction at that time, if the target moving speed in the radar direction changes every moment, it fluctuates with each antenna scan. Will be.
[0088]
In the related art, an operator visually checks a target spectrum continuously displayed in the classification mode, and classifies the target based on his / her own visual memory and classification experience. On the other hand, in the present invention, each unit of the classification processing system 6 is operated so that the device performs the work conventionally performed by a human.
[0089]
In order to perform target classification using the target spectrum that fluctuates every moment even for the same target, it is difficult to depend on the target velocity in the radar direction or the input signal amplitude that changes depending on the target distance. It is important to hold the characteristic spectrum waveform at the stage before the classification processing. For example, if the target is a vehicle, the Doppler frequency range in which a categorically significant target spectrum appears is between 0 and 2 fp, and the relative relationship of the spectrum waveform to the peak value of the spectrum is a specific relationship depending on the type of the target. become. Here, fp is the Doppler frequency corresponding to the target velocity in the radar direction, and is usually the Doppler frequency when the spectrum has a peak value. Therefore, it is effective to use this relative relationship as a database for classification processing.
[0090]
In the radar signal processing device 3 of the present embodiment, a relative spectrum is obtained by dividing the power and the Doppler frequency of the target spectrum by the peak power and the Doppler frequency, respectively, and this relative spectrum is converted into a format suitable for classification processing. The data is converted into a unified standardized spectrum, and classification processing is further performed using an averaged spectrum obtained by averaging the standardized spectrum for each antenna scan.
[0091]
Hereinafter, the operation of each unit of the newly added classification processing system 6 in the radar signal processing device 3 of the present embodiment will be described.
[0092]
As a premise of performing the classification process using the normalized spectrum, it is necessary to remove unnecessary signals other than the classification target in the target spectrum. The reason is as follows. The spectrum component corresponding to the noise level and the spectrum component of the Doppler frequency on which the clutter is superimposed are unnecessary components that cannot be used for the classification process because they do not hold the target original normalized spectrum shape. Furthermore, when the average value of the normalized spectrum is calculated using these unnecessary components, the average power of the normalized spectrum at the normalized Doppler frequency of the unnecessary components is isolated from the power of the original target normalized spectrum. This is because there is a risk of doing so. For the above-described reason, the input target spectrum is extracted from the unnecessary signal removing unit 19 by extracting only the target spectrum within the classification processing filter range specified by the operator on the display control unit 4, as well as the noise component and the moving clutter component. Is removed.
[0093]
First, the target spectrum within the categorized effective filter range is compared with a threshold level set to a level slightly higher than the noise level in the noise remover 23, and the spectrum data below the threshold level TH is shown in FIG. It is set to “0” as shown in b).
[0094]
Subsequently, in the clutter remover 24, the spectrum data in the Doppler frequency range corresponding to the pass frequency band of the Doppler filter number of the detection system in which the clutter exists, transmitted from the clutter extraction unit 10, is shown in FIG. As described above.
[0095]
The target spectrum for which the unnecessary spectrum data power is set to “0” by the unnecessary signal removing unit 19 is format-converted by the spectrum normalizing unit 20 into a standardized spectrum that can be processed by the target classification processing unit 22 at the subsequent stage.
[0096]
First, the peak of the target spectrum for obtaining the relative spectrum is detected by the peak detector 25. Here, as shown in FIG. 3D, the peak of the target spectrum is detected by the peak detector 25 from within the Doppler frequency range corresponding to the pass bandwidth of the target detection filter number transmitted from the target tracking unit 9. Is done. This means that if a Doppler frequency that does not correspond to the target detection filter number transmitted from the target tracking unit 9 has a spectrum having a power larger than the target peak spectrum, the target spectrum is erroneously determined when the relative spectrum is obtained. There is an effect of preventing division by a Doppler frequency other than the center Doppler frequency.
[0097]
Note that the peak spectrum at the Doppler frequency that does not correspond to the target detection filter number is removed by the maximum value selector 14 in the detection / tracking system 5. Therefore, since this peak spectrum is a steep spectrum with a small spread on the Doppler frequency axis even if the peak value is large, it is unlikely that the speed corresponding to the Doppler frequency is the true target moving speed.
[0098]
Subsequently, the target spectrum is standardized by the standardization arithmetic unit 26 into a format suitable for processing in the target classification processing unit 22 in the subsequent stage, as shown in FIG. First, each data constituting the target spectrum is divided by the peak power detected by the peak detector 25 and its Doppler frequency to be converted into a relative spectrum.
[0099]
The relative power PNi for the i-th target spectrum component Pi on the Doppler frequency axis is obtained by the following equation.
PNi = Pi / Pp × K (i = 0, 1,..., N−1)
Here, Pp: peak power detected by the peak detector 25
K: constant (constant for adjusting the peak value of the standardized spectrum to the classification processing database held in the target classification processing unit 22)
n: the number of FFT points in the FFT processing unit 18
Here, when the relative power PNi exceeds K, the relative power is set to “0”.
[0100]
Further, the relative Doppler frequency FNi with respect to the i-th Doppler frequency Fi on the Doppler frequency axis is obtained by the following equation.
FNi = Fi / Fp (i = 0, 1,..., N-1)
Where Fp is the peak Doppler frequency detected by the peak detector 25 (the Doppler frequency corresponding to the target velocity in the radar direction).
n: the number of FFT points in the FFT processing unit 18
FN0 = 0 [Hz]
Here, the relative Doppler frequency FNi decreases when the peak Doppler frequency Fp is large, and increases when the peak Doppler frequency Fp is small. Therefore, the range or interval of data that the relative Doppler frequency FNi can take varies for each antenna scan depending on the target moving speed in the radar direction.
[0101]
Therefore, the relative Doppler frequency calculated by the above equation is sampled in a format suitable for the classification process, as shown in FIG. As in case A of FIG. 4, when the input relative Doppler frequency has a smaller interval than the standardized Doppler frequency after sampling in the classification processing format, it corresponds to the standardized Doppler frequency Fsx after sampling. The average value of the relative power at a plurality of relative Doppler frequencies is the normalized power after sampling at the normalized Doppler frequency Fsx. On the other hand, when the input relative Doppler frequency has a wider interval than the normalized Doppler frequency in the classification processing format as in the case B of FIG. 4, the relative Doppler frequency corresponding to the normalized Doppler frequency Fsx Is the normalized power after sampling at the normalized Doppler frequency Fsx.
[0102]
The standardized spectrum standardized by the spectrum standardizing unit 20 into a format suitable for the classification process is input to the spectrum averaging unit 21. The input standardized spectrum and the standardized spectrum (averaged spectrum) read out from the spectrum memory 28 in accordance with the tracking target number transmitted from the target tracking unit 9 and subjected to averaging processing up to the previous antenna scanning are as follows. As shown in FIG. 3 (f), the averaged value is averaged in the average value calculator 27, sent to the target classification processing section 22 as an averaged spectrum in the current antenna scanning, and is sent to the spectrum memory 28 of the tracking target number. Output and saved.
[0103]
Here, the averaging process in the spectrum averaging unit 21 is for calculating an average value of normalized powers at the same normalized Doppler frequency Fsx of the normalized spectrum. However, when the normalized power at a certain normalized Doppler frequency Fsy is 0, the normalized power on the non-zero side is left as an average value as it is. When both normalized powers at a certain normalized Doppler frequency Fsz are 0, the average value is 0.
[0104]
If a target whose tracking has been newly started or a standardized spectrum of a target that has been detected but not tracked is input, the normalized power of the spectrum memory 28 is all 0, so that the input is performed. The standardized spectrum is output as it is as the averaged spectrum.
[0105]
The averaged spectrum is input to the target classification processing section 22, where the target classification processing is performed. Here, the contents of the target classification processing may be any method as long as the processing uses a spectrum waveform as an information source as described above. Here, a database constructed in advance for each target type is used. The operation of the classification processing by evaluating the degree of coincidence of is described.
[0106]
Prior to performing the classification, the target classification processing unit 22 narrows down and selects the original database for calculating the coincidence based on the RCS, the moving speed, and the moving direction of the tracking target. First, the operation of narrowing down the database from the RCS and the moving speed will be described.
[0107]
The target RCS is generally given by the following equation from the radar equation.
RCS = (4π)³・ Pr ・ R⁴/ ｛Pt ・ Gt ・ Gr ・ λ²｝
Here, Pt: transmission power
Pr: received power
Gt: transmission antenna gain
Gr: receiving antenna gain
λ: free space wavelength
R: target distance
Here, Pt, Gt, Gr, and λ are known values specific to the radar device. Further, R and Pr are obtained from the target position obtained from the target tracking unit 9 and the received signal amplitude. Therefore, the target RCS can be calculated from the above equation.
[0108]
The calculated RCS and the target speed input from the target tracking unit 9 are accumulated for each antenna scan. Due to the characteristics of the target type, the probability that the target being tracked is a target that cannot have the stored target RCS or target speed is 0, and therefore the calculation of the degree of coincidence using the target type database is It becomes unnecessary.
[0109]
Next, an operation of selecting a database from a target moving direction will be described.
[0110]
In general, the target Doppler spectrum has an almost reverse arrangement of the spectrum on the Doppler frequency axis when approaching the radar and when distant from the radar. For example, if the target having the spectrum of FIG. 7 moves in the opposite direction with respect to the radar at the same speed, the spectrum of f1 appears as the spectrum of fn−1, and the spectrum of fn−1 appears as the spectrum of f1. However, the target structure generally does not have exactly the same shape before and after the moving direction, and the situation of exposure of the rotating part in the radar direction is different. Therefore, the reversal of the arrangement of the spectrum on the Doppler frequency axis due to the reversal of the target moving speed in the radar direction mainly appears near the Doppler frequency where the spectrum has a peak.
[0111]
Therefore, it is desirable that the spectrum serving as a database has at least two cases, that is, a case where the target approaches the radar and a case where the target moves away from the radar. It is desirable to have each. When calculating the degree of coincidence between the input averaged spectrum and the database, a database of the aspect angle closest to the aspect angle calculated from the moving direction and the target direction of the target is used.
[0112]
Using the database narrowed down by the above operation, the degree of coincidence between the input averaged spectrum and the database for each target type is evaluated. The degree of coincidence is, for example, a unit standard obtained by calculating the squared error of the normalized power of the same normalized Doppler frequency and dividing the sum of the squared errors by the number of samples of the normalized Doppler frequency used for the calculation of the squared error. Can be evaluated based on the magnitude of the square error per normalized Doppler frequency.
[0113]
At the time of evaluation of the degree of coincidence, if there is a normalized Doppler frequency whose input averaged spectrum data is 0, it is excluded from the calculation of the square error. The degree of coincidence between the input averaged spectrum and a plurality of databases different for each target type can be evaluated by performing a stepwise threshold determination for a square error per unit normalized Doppler frequency. The evaluation result of the degree of coincidence and the square error per unit normalized Doppler frequency are output to the display control unit 4 as a part of the classification processing result and displayed.
[0114]
The orientation result and tracking result obtained by the detection / tracking system 5 and the target spectrum, standardized spectrum, averaged spectrum, and classification result obtained by the classification processing system 6 are displayed on the screen of the display control unit 4. You. Thus, unlike the related art, the operator can easily obtain the target search and tracking and the classification result without stopping the search and tracking.
[0115]
FIG. 5 is a block diagram showing a second embodiment of the radar signal processing device according to the present invention. Hereinafter, description will be made based on this drawing.
[0116]
The radar signal processing device 33 of this embodiment differs from the radar signal processing device 3 of FIG. 1 in the configuration and operation of the spectrum averaging unit 31 and the output data to the classification processing system 36 of the target tracking unit 9. Is that the scan number of the tracking target has been added to. Therefore, the configuration and operation of the spectrum averaging unit 31 will be mainly described here.
[0117]
The spectrum averaging unit 31 includes an invalid scanning number calculator 29, an integrator 30, and an average value calculator 37. The invalid-scanning-number calculator 29 obtains the number of scans at which the normalized power for each normalized Doppler frequency sampled in the classification processing format becomes 0 (hereinafter referred to as “invalid antenna scanning number”). The integrator 30 integrates, for each normalized Doppler frequency, the normalized power of the normalized spectrum that has been standardized for classification processing. The average calculator 37 receives the scan number input from the target tracking unit 9 indicating the number of scans in which the target tracking for the tracking target has succeeded, the invalid antenna scan number input from the invalid scan number calculator 29, and the integration. An average value of the normalized power is obtained for each normalized Doppler frequency based on the integration result up to the current antenna scanning input from the detector 29.
[0118]
The spectrum averaging unit 21 in FIG. 1 calculates an average value between the input standardized spectrum and the averaged spectrum up to the previous antenna scan. On the other hand, the spectrum averaging unit 31 of the present embodiment integrates all the effective spectrum data whose normalized power at the same normalized Doppler frequency is not 0 among the normalized spectrums input up to the current antenna scanning. Then, an averaged spectrum is obtained by dividing the integration result by the number of effective scans whose data is not zero. Hereinafter, the operation will be described.
[0119]
The invalid scanning number calculator 29 counts and holds the invalid scanning number Nz at which the data becomes 0 for each standardized Doppler frequency, and every time the standardized spectrum of the tracking target is input, the standardized Doppler frequency is calculated. The number of invalid scans Nz in each current antenna scan is output to the average calculator 27. The integrator 29 integrates the normalized power for each normalized Doppler frequency every time the normalized spectrum of the tracking target is input, and outputs the integrated power to the average calculator 27.
[0120]
When the scan number input from the target tracking unit 9 is k, the integration result PSi up to the current antenna scan at the i-th normalized Doppler frequency is calculated by the following equation.
PSi = Σ^k _{m = 1}(Pim)
Here, Pim is the normalized power at the scan number m at the i-th normalized Doppler frequency.
[0121]
The averaging calculator 37 calculates an averaging spectrum for target classification using the number of invalid scans and the integration result input for each normalized Doppler frequency. When the scan number is k, the averaged normalized power PAi at the i-th normalized Doppler frequency is calculated by the following equation using the integration result PSi and the number of invalid scans Nzi at the i-th normalized Doppler frequency. You.
PAi = PSi / (k-Nzi)
[0122]
The averaged spectrum obtained by the above processing is subjected to classification processing in the target classification processing unit 22 in the same procedure as in the case of the radar signal processing device 3 of FIG.
[0123]
Note that the present invention is not limited to radar using electromagnetic waves, but can also be applied to sonar and the like using sound waves.
[0124]
【The invention's effect】
According to the radar signal processing device of the present invention, target classification can be executed quickly and accurately. The reason is that by normalizing both the power and the Doppler frequency with respect to the Doppler spectrum that changes variously due to the fluctuation of the moving direction and speed of the target, it is possible to accurately extract the relative relationship specific to the target type. That's why. As a result, it is only necessary to construct a collation database for the standardized Doppler spectrum instead of all Doppler spectra, so that the time required for collation can be reduced.
[0125]
According to the radar signal processing device of the second aspect, since unnecessary components corresponding to the noise level are removed from the target spectrum and output to the spectrum normalizing unit, the target can be classified more accurately.
[0126]
According to the radar signal processing device of the third aspect, a plurality of normalized spectra for the same target input by a plurality of antenna scans are averaged, and the average value is output as an averaged spectrum. Since the target is classified based on the normalized spectrum, even if the Doppler spectrum changes according to the moving direction and speed of the target for each antenna scan, the target can be classified more accurately in combination with the standardization described above.
[0127]
According to the radar signal processing device of the fourth aspect, an average value is obtained between the standardized spectrum in the current antenna scanning and the averaged spectrum held in the spectrum memory, and the average value is averaged. By storing the spectrum in the spectrum memory and outputting the spectrum to the target classification processing unit, it is not necessary to store the standardized spectrum for each antenna scan, so that the storage capacity can be reduced.
[0128]
According to the radar signal processing apparatus of the present invention, only a signal having a specific Doppler frequency is extracted from the reflected signals, and a signal whose level is equal to or more than a specified level and whose range is equal to or more than a predetermined length is cluttered. By judging that clutter can be eliminated, the accuracy of the classification process can be improved.
[0129]
According to the radar signal processing device of the present invention, the target Doppler frequency range is calculated using the Doppler filter information in the detection / tracking system, and the peak power of the target spectrum is detected from the Doppler frequency range. Accordingly, clutter and noise can be eliminated, so that the accuracy of the classification process can be improved and the peak search can be facilitated.
[0130]
According to the radar signal processing apparatus of the ninth aspect, by using the database constructed for each target aspect angle and the calculated aspect angle, the aspect angle is also considered, so that the accuracy of the classification processing can be improved. Can be further improved.
[0131]
According to the radar signal processing device of the tenth aspect, the type of the target is narrowed based on the target RCS and the target moving speed, and the classification process is performed only on the narrowed type, so that the efficiency of the classification process can be improved. . For example, there is a possible range of the target RCS and the target moving speed according to a person, a car, and the like.
[0132]
In other words, according to the radar signal processing device of the present invention, it is possible to perform target classification processing while performing search and tracking of a target. The reason is that from the Doppler spectrum of the target, which can be obtained only intermittently for each antenna scan, and thus varies variously depending on the movement direction and movement speed of the target, the relative relationship inside the spectrum specific to the target type is calculated. Means for normalizing the spectrum for both power and Doppler frequency to extract, and furthermore, the standardized target spectrum obtained for each antenna scan with respect to the same tracking target, over the antenna scan. This is because there are means for averaging, and means for classifying the target using the averaged spectrum.
[0133]
In addition, the labor and skill of the operator required for the target classification process are reduced. The reason is that the function of outputting as a standardized spectrum indicating the relative relationship with the peak value of the spectrum which is hardly dependent on the change in the target speed of the target Doppler spectrum, and this normalized spectrum is averaged over the antenna scanning This is because it has a function of outputting an averaged spectrum, and further has means for automatically performing a target classification process using the averaged spectrum.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a first embodiment of a radar signal processing device according to the present invention.
2A and 2B are graphs showing a Doppler spectrum processing process in the radar signal processing apparatus of FIG. 1, wherein FIG. 2A shows an input target Doppler spectrum, FIG. 2B shows a Doppler spectrum at the time of noise removal processing, and FIG. Is the Doppler spectrum at the time of clutter removal processing.
3A and 3B are graphs showing a Doppler spectrum processing process in the radar signal processing device of FIG. 1, wherein FIG. 3D is a Doppler spectrum at the time of peak detection processing, and FIG. 3E is a normalized spectrum after the spectrum normalization processing. The normalized spectrum held in the spectrum memory, and (f) is the averaged spectrum.
FIG. 4 is a table showing a method of calculating a standardized spectrum in a format suitable for classification processing in the radar signal processing device of FIG. 1;
FIG. 5 is a block diagram showing a second embodiment of the radar signal processing device according to the present invention.
FIG. 6 is a block diagram showing a conventional radar signal processing device.
FIG. 7 is a graph showing an example of a target Doppler spectrum.
FIGS. 8A and 8B are graphs showing a relationship between a Doppler filter of a detection / tracking system and a classification processing system, wherein FIG. 8A is a detection / tracking system and FIG. 8B is a classification processing system.
[Explanation of symbols]
1 Antenna
2 Transceiver
3,33 Radar signal processor
4 Display control unit
5 Detection and tracking system
6,36 Classification system
7 Clutter suppression unit
8 Target detection / location section
9 Target tracking unit
10 Clutter extraction unit
11 Canceller
12 Doppler filter group for detection system
13 CFAR processor
14 Maximum value selector
15 Level judgment device
16 Range judgment device
17 Clutter filter selector
18 FFT processing unit (target spectrum output unit)
19 Unwanted signal remover
20 Spectrum Standardization Department
21,31 Spectrum averaging unit
22 Target classification processing section
23 Noise remover
24 Clutter remover
25 Peak detector
26 Standardized arithmetic unit
27,37 Average calculator
28 Spectrum Memory
29 Invalid scan number calculator
30 integrator

Claims (10)

In a radar signal processing device including a detection and tracking system that performs detection and tracking of the target based on a reflection signal from the target, and a classification processing system that classifies a reflection object based on a Doppler spectrum of the reflection signal,
The classification processing system includes:
A target spectrum output unit that inputs the position of the target from the detection / tracking system and outputs the Doppler spectrum at that position as a target spectrum,
A spectrum normalizing unit that relativizes the power and the Doppler frequency constituting the target spectrum by dividing by the peak power and the Doppler frequency, and outputs the relativized spectrum as a normalized spectrum converted into a predetermined format. When,
A target classification processing unit that classifies the target based on the standardized spectrum,
A signal processing device for radar, comprising: The classification processing system includes:
An unnecessary signal removing unit that removes an unnecessary component corresponding to a noise level from the target spectrum and outputs the signal to the spectrum normalizing unit,
The radar signal processing device according to claim 1. The classification processing system includes:
A spectrum averaging unit that averages a plurality of the normalized spectra for the same target input by a plurality of antenna scans and outputs the average value as an averaged spectrum,
The target classification processing unit classifies the target based on the averaged spectrum,
The radar signal processing device according to claim 1. The spectrum averaging unit includes:
An average value is obtained between the normalized spectrum in the current antenna scanning and the averaged spectrum held in the spectrum memory,
Outputting the average value to the target classification processing unit while holding the average value in the spectrum memory as the averaged spectrum,
The radar signal processing device according to claim 3 . The spectrum averaging unit includes:
For each antenna scan, the integrated value of the normalized power for each normalized Doppler frequency that constitutes the normalized spectrum, and the number of effective scans whose normalized power was an effective value other than 0,
By dividing the integral value by the number of effective scans, an average value of normalized power for each normalized Doppler frequency is calculated,
Outputting the average value to the target classification processing unit as the averaged spectrum,
The radar signal processing device according to claim 3 . The detection and tracking system includes:
A Doppler filter group including a plurality of Doppler filters that extract and output only a signal having a specific Doppler frequency from the reflected signals,
For the output signal of each Doppler filter, a signal whose level is equal to or greater than a specified level and whose range is equal to or greater than a predetermined length is determined as clutter, and the result of determining whether or not clutter exists for each Doppler filter at the target position And a clutter extraction unit that outputs the target classification processing unit,
The radar signal processing apparatus according to claim 1, 2, 3, 4, or 5. The spectrum normalization unit,
Using the Doppler filter information in the detection and tracking system to calculate the Doppler frequency range of the target,
Detecting the peak power of the target spectrum from the Doppler frequency range,
The radar signal processing device according to claim 1, 2, 3, 4, 5, or 6. The target classification processing unit,
Having a database consisting of the standardized spectrum for each type of reflective object,
Classifying the target by determining the degree of coincidence between the averaged spectrum and the database,
The radar signal processing device according to claim 1, 2, 3, 4, 5, 6, or 7. The target classification processing unit,
Having a database constructed for each target aspect angle indicating the angle between the moving direction of the target and the radar direction,
A target position and a target moving direction are input from the detection / tracking system, an aspect angle of the target is calculated, and the target is classified using the database corresponding to the calculated aspect angle.
The radar signal processing device according to claim 1, 2, 3, 4, 5, 6, 7, or 8. The target classification processing unit,
A target RCS is calculated based on a target position and a target received signal amplitude input from the detection / tracking system, and a type of a target assumed is narrowed down based on the target RCS and a target moving speed input from the detection / tracking system. , Categorize goals only for the narrowed types,
The radar signal processing device according to claim 1, 2, 3, 4, 5, 6, 7, 8, or 9.

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