JP2010078364A - Radar apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radar apparatus for detecting reflective objects within a set distance range. <P>SOLUTION: A received signal outputted from a light receiving circuit according to the intensity of reflected light of a laser is converted to a digital signal by an AD converter. Peak extraction means 44 extracts a group of sequential digital signals that are larger than a peak threshold value as a peak region, and assigns a peak number except 0. Map comparison means 60 determines the peak region as an effective peak region when at least one of the digital signals constituting the peak region having a peak number except 0 has a signal value larger than map data stored in a MAP DPRAM 56 for every sampling number, and selects all the digital signals constituting the effective peak region as effective signals. A distance calculation means 64 estimates a peak position of the effective peak region, based on the digital signals constituting the effective peak region, and calculates the distance to a reflective object. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a radar apparatus that detects a reflection object based on a reflected wave with respect to a transmission wave.

2. Description of the Related Art Conventionally, for example, a radar device that measures a distance from a reflecting object based on a time from receiving a reflected wave by irradiating a laser as a transmitted wave and receiving a reflected wave after irradiating the transmitted wave is known. (For example, refer to Patent Document 1). In Patent Document 1, the threshold value is variably adjusted in accordance with the received light value of the external light in order to determine that the reflected light from the reflecting object is received without being affected by the external light such as sunlight and fluorescent lamps. is doing.
JP 2000-356777 A

By the way, not only a laser but the reflected wave with respect to the transmitted wave transmitted in order to detect a reflecting material is reflected and received from every distance. Such reflected waves include unnecessary objects as shown below.
(1) Noise generated when a transmission wave is irradiated.
(2) When the radar device is mounted on the vehicle, a reflected wave of splashing splashed by the immediately preceding vehicle.
(3) When the distance range to be detected is determined, the reflected wave from the reflector in the other distance range.

  However, in Patent Document 1 described above, although the threshold value is variably adjusted according to the received light value of external light, the threshold value is adjusted uniformly. As a result, there is a problem in that it is not possible to select unnecessary reflected waves as described above and effective reflected waves to be detected.

  The present invention has been made to solve the above problem, and an object of the present invention is to provide a radar apparatus that detects a reflector within a set distance range.

  According to the first to sixth aspects of the present invention, the reception unit receives the reflected wave reflected by the reflecting object with respect to the transmission wave, and is set out of the reception signals output by the reception unit according to the intensity of the reflected wave. The signal selection means selects the received signal of the reflected wave reflected from the selected distance range as an effective signal. Then, based on the effective signal selected by the signal selection means, the detection means detects the reflecting object.

  As a result, the reflecting object can be detected based on the effective signal from the set distance range, and therefore the detection means needs to perform the reflecting object detection process on the received signal from outside the set distance range. Absent. As a result, the time required for the reflection detection process can be shortened. Further, it is possible to prevent erroneous detection of a reflected object by processing a received signal from outside the set distance range.

According to the second aspect of the present invention, the detecting means calculates the distance to the reflecting object based on the time from the transmission unit emitting the transmission wave to the location corresponding to the reflecting object in the effective signal.
This eliminates the need for the detection means to calculate the distance to the reflecting object for a received signal from outside the set distance range. As a result, the time required for calculating the distance to the reflecting object can be shortened.

  According to the third aspect of the present invention, the AD conversion unit converts the reception signal output from the reception unit into a digital signal, and the signal selection unit selects the digital signal converted by the AD conversion unit from a set distance range. The reflected reflected wave digital signal is selected as an effective signal.

Thus, by converting the received signal into a digital signal, signal processing on the received signal is facilitated.
According to the fourth aspect of the present invention, the effective signal value set in accordance with the distance range is stored in the effective signal value storage unit for each sampling point that the AD conversion unit performs AD conversion. The digital signal output from the conversion means and the effective signal value are compared at each sampling point, and the digital signal larger than the effective signal value among the digital signals output from the AD conversion means is reflected on the effective reflected wave from the distance range. Select as signal.

  In this way, since the effective signal is selected by comparing the digital signal with the effective signal value at each sampling point for converting the received signal into a digital signal, the distance range and the effective signal value for selecting the effective signal can be freely set. The degree becomes higher.

  By the way, when the digital signal is compared with the valid signal value at each sampling point for converting the received signal into a digital signal and a digital signal larger than the valid signal value is selected as the valid signal, the digital signal below the valid signal value is invalid. Signal. As a result, a portion below the effective signal value is removed from the digital signal forming the peak region corresponding to the reflector. Then, the shape of the peak region formed by the effective signal from which the portion below the effective signal value is formed may be significantly different from the shape of the peak region before the portion below the effective signal value is removed. When the shape of the peak region changes in this way, the peak position of the peak region may deviate from the correct original position. Since the peak position corresponds to the position of the reflector, the position of the reflector may not be detected with high accuracy if the peak position is shifted.

  Therefore, according to the invention described in claim 5, the peak extraction means extracts a signal group continuously larger than a predetermined peak threshold from the digital signal output from the AD conversion means as a peak area, and stores the effective signal value. The means stores an effective signal value set in accordance with the distance range for each sampling point that the AD conversion means performs AD conversion. Then, the signal selection means selects all digital signals in the peak area having a digital signal larger than the effective signal value among the peak areas extracted by the peak extraction means as effective signals.

  Thereby, the digital signal of the peak area which has a digital signal larger than an effective signal value among the peak areas extracted by the peak extracting means is selected as an effective signal including a portion below the effective signal value. As a result, the shape of the peak region selected by the signal selection means is the same as the shape when selected by the peak extraction means. Therefore, the position of the reflector can be detected with high accuracy based on the peak position of the peak region.

  According to the invention described in claim 6, the peak position estimation unit estimates the peak position of the peak region selected by the signal selection unit in the invention described in claim 5, and the detection unit is configured such that the transmission unit emits the transmission wave. Then, the distance to the reflector is calculated based on the time from the peak position to the peak position.

Thereby, based on the peak position estimated with high accuracy, the distance to the reflector can be detected with high accuracy based on the time from irradiation of the transmission wave to the peak position.
The functions of the plurality of means provided in the present invention are realized by hardware resources whose functions are specified by the configuration itself, hardware resources whose functions are specified by a program, or a combination thereof. The functions of the plurality of means are not limited to those realized by hardware resources that are physically independent of each other.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a radar apparatus 10 according to the present embodiment.
(Radar device 10)
The radar apparatus 10 includes a CPU 20, a light emitting circuit 22, a light receiving circuit 24, an external information output circuit 26, an AD converter 30, a distance measuring unit 40, and the like.

  The CPU 20 controls the light emitting circuit 22 and the light receiving circuit 24 by executing a control program stored in a storage device (not shown), and outputs the distance information to the reflecting object output from the distance measuring means 40 as an external information output circuit. 26 to other external ECUs and the like.

  The light emitting circuit 22 serving as a transmission unit includes a laser diode, a light emitting lens, a scanner, and the like. The laser diode is driven by a drive signal from the CPU 20 and irradiates the laser as a transmission wave through the light emitting lens and the scanner. The scanner is composed of, for example, a polygon mirror. As the polygon mirror rotates according to the drive signal from the CPU 20, the laser irradiated by the laser diode scans a predetermined angular range.

  The light receiving circuit 24 as a receiving unit includes a condenser lens and a light receiving element such as a photodiode. The condensing lens condenses a laser that is a reflected wave reflected by the reflector. The light receiving element outputs a voltage signal corresponding to the intensity of the focused laser as a reception signal.

  The AD converter 30 as AD conversion means samples the received signal output from the light receiving circuit 24 at a constant sampling frequency, for example, 160 [MHz], and converts it into a digital signal. At a sampling frequency of 160 [MHz], the sampling period is 6.25 [ns] and the sampling distance unit is 0.9375 [m]. In order to sample in such a short cycle, a pipelined AD converter that operates at high speed is used as the AD converter 30.

  Further, the number of samplings by the AD converter 30 is determined by the maximum distance measured by the radar apparatus 10. Assuming that the maximum measurement distance is X [m], as described above, when the sampling frequency is 160 [MHz] and the sampling distance unit is 0.9375 [m], the sampling number is X / 0.9375.

  The AD converter 30 stops AD conversion when sampling X / 0.9375 times after starting laser irradiation from the light emitting circuit 22, and starts AD conversion at the next laser irradiation. Alternatively, the AD converter 30 continues the AD conversion without stopping the sampling, and the distance measuring means 40 reads out X / 0.9375 data from the AD converter 30 for each measurement process. Reading may be stopped.

  FIG. 3 shows an example of a digital signal sequence 100 obtained by AD converting the reception signal output from the light receiving circuit 24. The digital signal output by the AD converter 30 for each sampling period is given a sampling number according to the sampling order, that is, as time elapses after the laser irradiation.

The distance measuring means 40 is realized by, for example, an FPGA (Field Programmable Gate Array). FIG. 2 is a block diagram showing the configuration of the distance measuring means 40.
The peak threshold value calculation means 42 calculates a peak threshold value for determining whether or not the peak area is a peak area when the peak extraction means 44 described later extracts the peak area.

  By the way, when the reception signal input from the light receiving circuit 24 to the AD converter 30 is AC-coupled, the output of the AD converter 30 is ideally 0 when the light receiving circuit 24 does not receive the reflected wave. . However, in practice, random noise centered at 0 is generated. In order to remove this random noise, it is conceivable to use (average value of random noise × coefficient) as a threshold value. As the average value of the random noise, a value obtained by adding a predetermined number of digital signal output values sampled and output by the AD converter 30 in a state where the light emitting circuit 22 is not irradiated with a laser and dividing the digital signal by the predetermined number is used. . The peak threshold value calculation means 42 calculates an average value of random noise in a state where the light emitting circuit 22 is not irradiating a laser, for example, at a constant cycle every several seconds, and sets (average value of random noise × coefficient) as a peak threshold value. Output as. The peak threshold value does not change until the next calculation cycle, and the same value is output. And if the magnitude | size of random noise changes in a calculation period, the magnitude | size of a peak threshold value will also change.

  It is desirable that the CPU 20 can change a predetermined number for adding the output value of the digital signal when calculating the average value of the random noise and a coefficient for obtaining a product of the average value of the random noise to an appropriate value.

  The peak extraction unit 44 extracts a group of digital signals continuously larger than the peak threshold calculated by the peak threshold calculation unit 42 as a peak region from the digital signal AD-converted by the AD converter 30. As shown in the upper digital signal sequence 100 in FIG. 4 before the peak region extraction and the lower digital signal sequence 110 in FIG. 4 after the peak region extraction, the peak extraction unit 44 is configured to output the digital signal extracted as the peak region. The signal value of the digital signal below the peak threshold is set to 0.

  As shown in the lower part of FIG. 4, the peak extraction unit 44 assigns a peak number to each extracted peak region. The peak number is assigned to each sampling number of the digital signal that constitutes the peak area. For example, as shown in FIG. 5, three digital signals surrounded by a one-dot chain line constituting a peak area of peak number 1 and four digital signals surrounded by a one-dot chain line constituting a peak area of peak number 2 Digital signal, five digital signals surrounded by a one-dot chain line constituting a peak area of peak number 3, one digital signal surrounded by a one-dot chain line constituting a peak area of peak number 4, peak number 5 Peak numbers 1, 2, 3, 4, and 5 are assigned to the sampling numbers of 11 digital signals surrounded by a one-dot chain line that constitutes the peak region of FIG. On the other hand, the peak extraction unit 44 sets the signal value of the digital signal equal to or lower than the peak threshold value to 0, and adds 0 as the peak number to the sampling number of each digital signal.

  The signal value of the digital signal extracted as the peak area is left as it is, and the peak value is obtained for the peak waveform result when the signal value of the digital signal equal to or lower than the peak threshold is 0 and the sampling number of the digital signal AD-converted by the AD converter 30. The numbered peak number results are output from the peak extraction means 44 in synchronization. The peak waveform result is recorded in the peak waveform recording RAM 52 for each sampling number, and the peak number result is recorded in the peak number recording RAM 54 for each sampling number.

  Here, an example of output data of the peak extraction means 44 is shown in FIG. Each of the six columns in FIG. 6 is composed of three stages. The upper part of each column represents the sampling number starting from 0. In FIG. 6, some sampling numbers are omitted. The middle row of each column shows the result of leaving the signal value of the digital signal extracted as the peak region as it is and setting the signal value of the digital signal below the peak threshold to 0. The parentheses in the middle row represent signal values before being set to zero. In FIG. 6, the peak threshold value is set to 200. The lower part of each column indicates the peak number of the peak region. In the peak waveform recording RAM 52, the upper stage (sampling number) and middle stage (signal value) of each column are recorded in association with each other, and the upper stage (sampling number) and lower stage (peak number) of each column are recorded in the peak number recording RAM 54. Are recorded in association with each other.

  When the recording into the peak waveform recording RAM 52 and the peak number recording RAM 54 is completed, the RAM output control means 50 outputs the data recorded in the peak waveform recording RAM 52, the peak number recording RAM 54, and the map DPRAM 56 in synchronization.

  In the map DPRAM 56 as the effective signal value storage means, map data is recorded as an effective signal value for each sampling number. The map data recorded in the map DPRAM 56 can be freely changed by a personal computer (PC) as external rewriting means.

  The map comparison means 60 as the signal selection means inputs data output in synchronization from the peak waveform recording RAM 52, the peak number recording RAM 54, and the map DPRAM 56. Then, the map comparing means 60 includes a signal value of a digital signal constituting a peak region having a peak number other than 0 among the data recorded in the peak waveform recording RAM 52 and the peak number recording RAM 54, and a sample of this digital signal. The map DPRAM 56 corresponding to the number is compared with the map data for filtering.

  If at least one of the digital signals constituting each peak area has a signal value larger than the map data of the corresponding sampling number, the map comparing means 60 determines that the peak area is an effective peak area and constitutes an effective peak area. Select all digital signals as valid signals. Then, the map comparison means 60 records the sampling number and peak number of the digital signal selected as the effective signal in the effective peak number recording RAM 62.

  On the other hand, if the signal values of all the digital signals constituting each peak area are equal to or less than the map data of the corresponding sampling number, the map comparison means 60 determines that the peak area is an invalid peak area, and determines the invalid peak area as the invalid peak area. 0 is added as a peak number to the sampling number of all digital signals to be configured. Then, the map comparison means 60 records the sampling number and peak number 0 of all digital signals constituting the invalid peak area in the effective peak number recording RAM 62.

  Further, the map comparison means 60 sets the corresponding sampling number and peak number 0 to the effective peak for a digital signal whose signal value is 0 before comparing with the map data and whose peak number is 0. Recorded in the number recording RAM 62.

  For example, in FIG. 7, the map comparison means 60 compares the map data 120 set for each sampling number with the digital signal constituting the peak area of the digital signal sequence 110 extracted as the peak area. And the map comparison means 60 deletes the peak area of the peak numbers 1-4, and makes the peak area of the peak numbers 5-12 an effective peak area. The map data 120 in FIG. 7 is set so as to remove a reception signal close to the radar apparatus 10. Therefore, for example, it is possible to remove noise generated when laser is emitted from the light emitting circuit 22 and a reception signal of a reflected wave from splashing splashed by the immediately preceding vehicle.

  In FIG. 8, the map comparison means 60 compares the other map data 130 set for each sampling number with the digital signal constituting the peak area of the digital signal sequence 110 extracted as the peak area. And the peak area | region of the peak numbers 1-5 and the peak numbers 10-12 is deleted, and the peak area of the peak numbers 6-9 is made into an effective peak area | region. The map data 130 in FIG. 8 is set so as to remove the near reception signal and the far reception signal from the radar apparatus 10 and validate the reception signal in the intermediate distance range therebetween.

  In the present embodiment, since map data is set for each sampling number, the distance range for selecting an effective peak region composed of effective signals and the degree of freedom in setting effective signal values are high.

  When the processing of the map comparison means 60 is completed for all sampling elements within the maximum measurement distance and the sampling number and the peak number of the effective peak area are recorded in the effective peak number recording RAM 62, the RAM output control means 50 The recording data is synchronously output to the peak waveform recording RAM 52 and the effective peak number recording RAM 62. The peak waveform recording RAM 52 outputs the same data as the data output to the map comparison means 60.

  Here, in the present embodiment, a group of digital signals that are continuously larger than the peak threshold is extracted from the digital signal output from the AD converter 30 as a peak region, and the map data for filtering is used to extract the peak region from the peak region. The effective peak area was extracted. The reason why the effective peak region is not directly extracted from the digital signal output from the AD converter 30 will be described below.

  As shown in FIG. 9A, when comparing the signal value of the digital signal sequence 140 from which the peak region is not extracted and the map data 150 for each sampling number, the digital signal having a larger signal value than the map data 150 Is valid, and it is determined that a digital signal having a signal value equal to or lower than the map data 150 is invalid. That is, in the digital signal sequence 140 of FIG. 9A, only three digital signals larger than the map data 150 are extracted as valid signals constituting the effective peak region, and other digital signals are signal values as invalid signals. Is set to 0.

  Then, as shown in FIG. 9B, an effective peak region is formed by three digital signals, so that a peak region that is significantly different from the shape corresponding to the peak region is extracted in FIG. It will be. If the peak position is estimated from such a peak region shown in FIG. 9B, there is a risk of deviation from the peak position estimated from the peak region in FIG.

  When the peak position is shifted, the time required from the start of laser irradiation from the light emitting circuit 22 to the peak position is shifted. The distance to the reflector is calculated by the following equation (1) from the time from the start of laser irradiation to the peak position corresponding to the reflector and the speed of light. As a result, when the peak position is deviated, the time from the start of laser irradiation to the peak position is deviated, resulting in an error in the distance to the reflector.

Distance = speed of light × time / 2 (1)
On the other hand, if a group of digital signals continuously larger than the peak threshold value is extracted as a peak area from the digital signal output from the AD converter 30 as in this embodiment, the processing is performed in units of peak areas. it can. As a result, when an effective peak area larger than the map data is extracted from the extracted peak area, the effective peak area can be extracted not in units of digital signals but in units of peak areas. The shape of the effective peak region extracted in peak region units is the same as the shape of the peak region before being extracted as the effective peak region. As a result, the peak position corresponding to the reflector can be estimated with high accuracy from the effective peak area, and the time from the start of laser irradiation to the peak position can be estimated with high accuracy, so the distance to the reflector can be accurately estimated. It can be calculated.

  The distance calculation means 64 as the detection means and the peak position estimation means estimates the peak position of the effective peak area based on the data output from the peak waveform recording RAM 52 and the effective peak number recording RAM 62, and expresses the distance to the reflector. Calculate from (1) and measure. First, the peak position estimation method by the distance calculation means 64 will be described with reference to FIG.

  If the maximum signal value of the digital signal in the effective peak region 160 shown in FIG. 10 is amax, the digital signal sandwiching the value of A calculated by the following equation (2) before and after the peak position of the effective peak region 160 There is one set for each. The distance calculating unit 64 sequentially compares the digital signal constituting the effective peak region 160 and A calculated by the equation (2) to obtain a set of corresponding digital signals. Note that the coefficient k in the equation (2) is set in a range of 0.5 ≦ k ≦ 0.7 from the waveform characteristics of the peak region, for example.

A = amax × k (0 <k <1) (2)
In FIG. 10, (t1, a1) and (t2, a2), (t3, a3) and (t4, a4) are a set of digital signals sandwiching the value of A up and down. tx (x = 1, 2, 3, 4) is the time from when the light emitting circuit 22 irradiates the laser to the sampling point by the AD converter 30, and is a value that is an integral multiple of the sampling period. ax (x = 1, 2, 3, 4) represents the signal value of the digital signal at time tx.

  When the time when the straight line connecting the two points of each set intersects with the signal value represented by A = amax × k is T1 and T2, respectively, and the sampling period is Δt, T1 and T2 are expressed by the following equation ( 3) and (4).

T1 = (A−a1) × Δt / (a2−a1) + t1 (3)
T2 = (a3-A) × Δt / (a3-a4) + t3 (4)
The time Tp corresponding to the peak position of the effective peak region 160 is calculated by the following equation (5).

Tp = (T1 + T2) / 2 (5)
The distance calculation unit 64 calculates the time Tp corresponding to the peak position of each effective peak region in this way, and calculates the distance to the reflector from the equation (1). The reason for calculating the time Tp and estimating the peak position of the effective peak region in this way is that the sampling point does not necessarily become the peak position of the effective peak region.

The estimation of the peak position of the peak region is not limited to the above method. For example, the position of the center of gravity of the digital signal constituting the peak area may be estimated as the peak position.
The distance to the reflecting object calculated by the distance calculating means 64 is output to the CPU 20 via the bus. The CPU 20 outputs the distance to the reflecting object to the outside of the radar apparatus 10 via the external information output circuit 26.

  When the CPU 20 outputs the distance to the reflecting object calculated by the distance calculating means 64 to the outside of the radar apparatus 10, the CPU 20 controls the light emitting circuit 22 to irradiate the next laser. Then, the distance measuring unit 40 performs the same processing as described above on the basis of the digital signal of the received signal output from the light receiving circuit 24 and AD converted by the AD converter 30 to the reflecting object existing in the set distance range. Measure distance.

  In the above-described embodiment, map data is set for each sampling point based on the set distance range, and a peak region having digital data larger than the map data is extracted from the peak region extracted by the peak extraction unit 44. Selected as the effective peak area. Thereby, the measurement process of the distance to the reflector in the set distance range is performed only for the digital data outside the set distance range without performing the process of measuring the distance to the reflector. As a result, it is possible to eliminate the distance measurement process for unnecessary reflectors, so that the time required for the distance measurement process can be shortened. Further, it is possible to prevent a reflection object from being erroneously detected by processing a digital signal outside the set distance range.

[Other Embodiments]
The transmission wave of the radar apparatus is not limited to the laser used in the above embodiment, and for example, a sound wave may be used.

  In the above embodiment, the reception signal output from the light receiving circuit 24 is converted into a digital signal by the AD converter 30, and the digital signal is processed to measure the distance to the reflecting object. On the other hand, the distance to the reflecting object may be measured by subjecting the received signal output from the light receiving circuit 24 to analog signal processing without AD conversion.

  Moreover, in the said embodiment, after extracting the group of digital signals continuously larger than a peak threshold value as a peak area, the peak area which has a digital signal larger than map data is made into an effective peak area comprised from an effective signal. Selected. On the other hand, the process of extracting the peak area based on the peak threshold value may be omitted, and a digital signal larger than the map data may be selected as an effective signal.

  Moreover, in the said embodiment, the distance to the reflector which exists in the set distance range was measured. On the other hand, the distance to the reflecting object is not measured, and the presence of the reflecting object in the set distance range may be detected.

  In the above embodiment, the map data in the map DPRAM 56 can be rewritten from an external personal computer. On the other hand, the CPU 20 may be configured to automatically rewrite the map data of the map DPRAM 56 in accordance with the surrounding situation in which the radar device 10 detects the reflected object, for example, the type of traveling road, illuminance, and the like.

  In the above-described embodiment, the functions of the means corresponding to the signal selection means, detection means, peak extraction means, and peak position estimation means described in the claims are defined by the FPGA (Field Programmable) whose function is specified by the circuit configuration itself. It is realized by hardware by Gate Array). On the other hand, at least a part of the functions of the above means may be realized by an electronic control unit (ECU) whose function is specified by software such as a control program.

  As described above, the present invention is not limited to the above-described embodiment, and can be applied to various embodiments without departing from the gist thereof.

The block diagram which shows the radar apparatus by this embodiment. The block diagram which shows the detail of a distance measurement means. The signal diagram which shows an example of AD conversion result. The signal diagram explaining extraction of a peak area. The signal diagram explaining extraction of a peak area. Explanatory drawing which shows the specific example of the extraction result of a peak area | region. The signal figure which shows the filtering result by map data. The signal diagram which shows the other filtering result by map data. The signal figure which shows the waveform when not performing the peak extraction by a peak threshold value. The signal diagram explaining the estimation method of the peak position of an effective peak area | region.

Explanation of symbols

10: Radar device, 20: CPU, 22: Light emitting circuit (transmitting unit), 24: Light receiving circuit (receiving unit), 30: AD converter (AD converting unit), 40: Distance measuring unit, 44: Peak extracting unit, 56: Map DPRAM (effective signal value storage means), 60: Map comparison means (signal selection means), 64: Distance calculation means (detection means, peak position estimation means)

Claims (6)

In a radar apparatus that irradiates a transmission wave and detects the reflection object based on a reflection wave from the reflection object,
A transmission unit for irradiating the transmission wave;
A receiver that receives the reflected wave reflected by the reflector with respect to the transmitted wave and outputs a received signal according to the intensity of the reflected wave;
Signal selection means for selecting, as an effective signal, a reception signal of the reflected wave reflected from a set distance range among reception signals output by the reception unit;
Detecting means for detecting the reflector based on the effective signal;
A radar apparatus comprising:   The said detection means calculates the distance to the said reflector based on the time to the location corresponded to the said reflector in the said effective signal after the said transmission part irradiates the said transmission wave, It is characterized by the above-mentioned. The radar apparatus according to 1. AD conversion means for converting the received signal output by the receiving unit into a digital signal,
The signal selection means selects, as an effective signal, a digital signal of the reflected wave reflected from the distance range among digital signals output from the AD conversion means.
The radar apparatus according to claim 1 or 2, wherein The AD conversion means further includes an effective signal value storage means for storing an effective signal value set according to the distance range for each sampling point AD converted,
The signal selection means compares the digital signal output from the AD conversion means with the effective signal value for each sampling point, and the digital signal larger than the effective signal value among the digital signals output from the AD conversion means. As an effective signal of the reflected wave reflected from the distance range,
The radar apparatus according to claim 3. Peak extraction means for extracting, as a peak region, a signal group continuously larger than a predetermined peak threshold among the digital signals output by the AD conversion means;
Effective signal value storage means for storing an effective signal value set according to the distance range for each sampling point AD converted by the AD conversion means;
Further comprising
The signal selection unit is configured to select all digital signals in a peak region having a digital signal larger than the effective signal value in the peak region extracted by the peak extraction unit, and an effective signal of the reflected wave reflected from the distance range. Select as the
The radar apparatus according to claim 3. A peak position estimating means for estimating a peak position of the peak area;
The detection means calculates a distance to the reflector based on a time from the transmission unit irradiating the transmission wave to the peak position.
The radar apparatus according to claim 5.

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