JP2007316016A - Radar device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize measurement with high angular accuracy, even when beams are scanned at a high speed. <P>SOLUTION: The radar device converts a transmission wave motion to a transmission beam; therewith matches the arrival direction from a reflecting subject of an object to be observed, with the radiation direction of the transmission beam; performs beam scanning; receiving the reflected waves obtained by a plurality of arranged receiving elements by using a receiving beam; calculates the angular difference between the transmission beam and a reflecting beam thereof, based on the assumed distance between the beam scanning speed and the reflecting subject; selects only the receiving element that receives the receiving beam from among a plurality of receiving elements, in response to the angular difference; and obtains the receiving signal. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a radar apparatus that performs high-speed beam scanning and observes the distance of an object using a plurality of receiving elements.

  Radar devices have been used to measure the position of an object present at a remote point. In radar equipment, waves such as electromagnetic waves and sound waves are radiated into space, the waves reflected by the target object are received, and the received signal is analyzed to measure the distance and angle to the object. . The distance of the object can be measured, for example, by performing pulse modulation on the radiated electromagnetic wave and using the time difference from the transmission pulse emission until the reception pulse as the reflected wave is received. The angle of the position of the object can be observed by making the radiated electromagnetic wave into a beam, scanning the transmission beam in different angular directions, and measuring the received pulse. In particular, a radar apparatus using laser light as an electromagnetic wave is known to enable observation of an object with high angular resolution because the spread of the emitted beam can be extremely small (for example, Non-Patent Document 1). reference).

  In a radar apparatus that performs such beam scanning, the time required for observing a predetermined observation region, that is, the observation period is the width of the observation region, the beam width, the pulse repetition frequency (PRF), the beam scanning. It depends on the speed. For example, in order to shorten the observation period while fixing the width of the observation region and the beam width, the pulse repetition frequency is increased and the beam scanning speed is increased. However, there is a time difference proportional to the distance of the reflecting object between the time when the transmission pulse is emitted and the time when the reflected wave reflected by the object is received by the radar device. Therefore, when the beam scanning speed is increased, the beam direction changes during this time difference, and the directions of the transmission beam and the reception beam are shifted. That is, since the observation is performed by directing the reception beam in a direction different from the direction in which the radio wave is radiated, there arises a problem that the reflected wave cannot be received.

  In order to solve such a problem, a method has been proposed that enables target distance discrimination by using a detection means comprising a multi-detection element array and sequentially switching the reception output of each detection element by a signal processor. (For example, refer to Patent Document 1).

JP 58-96267 A (page 3) A. Akiyama et al. , Optical fiber imaging laser radar, Optical Engineering, vol. 44, no. 1, 2005.

In the case of the method disclosed in Patent Document 1, the resolution for distance discrimination, that is, the distance resolution is determined by the scanning speed. However, in order to obtain a sufficient distance resolution, a considerably high speed beam scanning is required. For example, when a beam width of 0.1 degrees and a distance resolution of 100 m are obtained, the scanning speed is 3 × 10 ⁵ degrees / second. Since it is not easy to obtain such a beam scanning speed, in order to obtain distance resolution, it is considered necessary to use in combination with a method of modulating a transmission wave like a pulse radar. However, Patent Document 1 does not disclose such transmission wave modulation or modulation conditions (pulse width conditions).
Some conventional radar apparatuses, such as that disclosed in Non-Patent Document 1, use a plurality of reception beams having different beam directions and simultaneously observe a plurality of directions. In such a radar apparatus, even if the reflected wave can be received, an error occurs in the target angle measurement in the long-distance observation in which the angle deviation of the transmitted / received beam occurs.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a radar apparatus that realizes measurement with high angular accuracy even when a beam is scanned at high speed.

  A radar apparatus according to the present invention radiates a wave in a space and receives a wave reflected by a reflecting object existing in the space, thereby measuring a reference timing signal in a radar apparatus that measures data related to the reflecting object. Transmitting means for generating a pulse-modulated wave based on the above, a radiating means for shaping the generated wave into a transmission beam and radiating it into the space, and a transmission beam and reception according to a predetermined beam scanning speed and scanning direction instruction Beam scanning means for scanning the beam at the same beam scanning speed and in the same direction or close to each other, receiving beam forming means for capturing only waves coming from a specific direction from the space, and outputting the waves, and shaping Received reflected signal is received by one of a plurality of arranged receiving elements by using the received beam. Based on the stage, a predetermined beam scanning speed, and a plurality of hypothetical reflecting object distances, the distance of the reflecting object is defined as an angle between the transmission and reception of the beam scanned by the beam scanning means in the time from transmission to reception. A transmission / reception gap angle calculation means for calculating each time, and a reception element for generating a switching timing for selecting a receiving element at a position where the reflected wave can be received based on the timing signal and the calculated transmission / reception gap angle In accordance with the switching timing generating means and the generated switching timing, a receiving device that selects only a receiving device at a position where the reflected wave can be received from a plurality of receiving devices and outputs a reception signal of the selected receiving device. An element switching means is provided.

  According to the present invention, a pulse-modulated wave is transmitted as a transmission beam and transmitted by beam scanning, and a reflected wave scanned in synchronization is received by one of a plurality of receiving elements arranged by a reception beam, At this time, the angle difference between the transmitted beam and its reflected wave is used to select only the receiving element received using the received beam. Therefore, the angle between the transmitted beam and the received beam is shifted due to the time difference between the transmitted and received signals. In addition, the reflected wave to be observed can be received without loss, and high-precision measurement that does not cause an error in angle measurement is possible even in long-distance observation with high-speed beam scanning.

Embodiment 1 FIG.
1 is a block diagram showing a functional configuration of a radar apparatus according to Embodiment 1 of the present invention. The radar apparatus according to the first embodiment, including other embodiments, employs a system in which a transmission wave is pulse-modulated in order to obtain distance resolution, and an example in which laser light is used as an electromagnetic wave to be emitted. Will be described.
In FIG. 1, a transmission unit 20 is means for generating laser light (wave) that is pulse-modulated based on a reference timing signal. The radiating unit 30 is a unit that shapes the generated laser light into a beam and radiates it into the space as a transmission beam. The beam scanning unit 40 is a means for scanning the transmission beam and the reception beam at the same beam scanning speed and in the same direction or close to each other in accordance with a predetermined beam scanning speed and a scanning direction instruction. The reception beam forming unit 50 is means for capturing only waves coming from a specific direction from the space and outputting the waves, that is, means for forming a reception beam. The light receiving unit (reception unit) 60 is a unit that receives a reflected wave by any one of a plurality of light receiving elements arranged using a shaped reception beam and obtains a reception signal. Based on a predetermined beam scanning speed and a plurality of assumed reflecting object distances, the transmission / reception deviation angle calculation unit 70 determines the angle of the beam scanning performed by the beam scanning unit 40 in the time from transmission to reception. It is a means for calculating the angle for each distance of the reflecting object. The light receiving element switching timing generating unit (receiving element switching timing generating means) 80 is a switching timing for selecting a receiving element at a position where the reflected wave can be received based on the timing signal and the calculated transmission / reception gap angle. Is a means for generating
The light receiving element switching unit (receiving element switching means) 90 selects only the receiving element at the position where the reflected wave can be received from the plurality of receiving elements in accordance with the generated switching timing, and the selected receiving element Means for outputting the received signal. The AD conversion unit 100 is means for digitally converting the reception signal output from the light receiving element switching unit 90. The detection processing unit 111 is a unit that extracts only the reflected wave component from the reflected object to be observed from the digitally converted received signal, and detects the distance and angle of the reflected object based on the extracted reflected wave component. . The angle correction unit 112 is means for correcting the angle of the reflecting object obtained by the detection processing unit 111 based on the transmission / reception gap angle and the beam scanning angle obtained from the beam scanning unit 40.

Next, the operation will be described.
The transmission unit 20 generates a pulse-modulated laser beam as a transmission pulse. The generation of the transmission pulse is performed at the timing when the reference timing signal generated by the control unit 10 is input to the transmission unit 20. The radiating unit 30 shapes the laser beam generated by the transmitting unit 20 into a beam and radiates it into the space. Specifically, the radiating unit 30 includes a lens or a reflector so that a feeding point that feeds the laser beam output from the transmitting unit 20 and the fed laser beam are focused in the distance or become a plane wave. Consists of a telescope with The laser light emitted from the radiation unit 30 is emitted in one direction in a beam shape, and the beam direction is changed by the beam scanning unit 40.

  The beam scanning unit 40 is supplied with a beam control signal that instructs a predetermined beam scanning speed and a scanning direction from the control unit 10. In accordance with these instructions, the beam scanning unit 40 performs scanning to change the directions of the transmission beam formed by the radiation unit 30 and the reception beam formed by the reception beam forming unit 50. As a method of changing the beam direction, for example, the beam scanning unit 40 is provided with a reflecting mirror, and the beam direction can be changed by mechanically changing the direction of the reflecting mirror surface. Alternatively, the beam scanning unit 40 may include a prism that refracts the beam direction, and the beam direction is changed by mechanically rotating the prism. As another method, there is a method in which the radar apparatus is mounted on a gantry provided with a mechanism that mechanically changes the orientation of the entire radar apparatus. In either case, in order to receive a reflected echo, the same beam scan is used for the transmission beam and the reception beam, except for an angle shift caused by a time difference between transmission and reception, which will be described later, and a difference between the widths of the transmission beam and the reception beam. It is necessary to perform beam scanning so as to be at the same speed and in the same direction or close to each other.

In the reception beam forming unit 50, only a wave coming from a specific direction is captured from the space. The reception beam forming unit 50 is composed of a telescope that forms an image of a reflected wave propagated from one direction to be observed at one point. However, the receiving beam direction is controlled by the beam scanning unit 40.
A light receiving unit 60 is placed at a position where the reflected beam of the reflected wave formed by the receiving beam forming unit 50 forms an image. The position where the reflected wave forms an image changes depending on the arrival direction of the reflected wave. Here, it is assumed that the light receiving unit 60 includes a plurality of light receiving elements, and these elements are arranged in a line. Further, the light receiving unit 60 is arranged so that the imaging position when the beam scanning unit 40 is not performing beam scanning, that is, when the beam is fixed, is the position of the light receiving element in the center of the light receiving unit 60. Suppose that
When the beam scanning is performed by the beam scanning unit 40, the arrival direction of the reflected wave is shifted by an angle determined by the distance of the object to be observed and the beam scanning speed as compared with the case where the beam direction is fixed. The arrangement direction of the light receiving elements is set so that the received beam forms an image on different light receiving elements in the light receiving unit 60 due to the difference between the transmission and reception deviation angles.

  Each light receiving element arranged in the light receiving unit 60 generates an electric signal corresponding to the intensity of the received reflected wave. The reflected wave in this case is received with a delay time corresponding to the distance of the reflecting object. Therefore, the time-series distribution of the electric signal corresponds to the distance distribution of the reflecting object. Of the electric signals output from the respective light receiving elements, only the electric signals of the light receiving elements arranged at the imaging position contain the reflected wave signal. Therefore, the light receiving element switching unit 90 selects a light receiving element at an imaging position of the received beam from the electric signals generated by all the light receiving elements.

The light receiving element as the imaging position is determined by the beam scanning speed and the distance (that is, the delay time) of the reflecting object. Therefore, first, the transmission / reception deviation angle calculation unit 70 calculates the angle difference between the radiation direction of the transmission beam and the arrival direction of the reflected wave based on the beam scanning speed given from the control unit 10 and the distance of the reflection object. Calculated as the deviation angle. Since the gap between transmission and reception differs depending on the distance, it is calculated for each distance. When the beam scanning speed is v _θ and the target observation distance is r, the transmission / reception deviation angle is calculated by equation (1).
θ _d = 2rv _θ / c (1)
Where c is the speed of light.
Here, the number of the central light receiving element is set to 0, and the light receiving elements are numbered 1, 2, 3,..., -1, -2, -3,. The image forming position is schematically shown in FIG. FIG. 2A shows a state in which the direction of the reflected wave input to the reception beam forming unit 50 is the front and forms an image on the light receiving element 0. On the other hand, FIG. 2B shows a state in which the direction of the reflected wave input to the reception beam forming unit 50 is slightly shifted and forms an image on the light receiving element 1. FIG. 2C shows a state in which the direction of the reflected wave is further shifted and an image is formed on the light receiving element 2.

The light receiving element switching timing generation unit 80 receives a reflected wave from a plurality of receiving elements based on the timing signal output from the control unit 10 and the transmission / reception shift angle calculation unit 70. A switching timing for selecting a light receiving element at a position where the light receiving is possible is generated and output to the light receiving element switching unit 90. The light receiving element switching unit (receiving element switching unit) 90 selects a light receiving element at a position where the reflected wave can be received from a plurality of receiving elements according to the switching timing generated by the light receiving element switching timing generation unit 80. To do. And the receiving signal obtained from the light receiving element which received the reflected wave is output.
Here, in the light receiving unit 60, if the interval between the plurality of light receiving elements corresponds to the beam direction angle difference Δθ, the number _nel of the light receiving element selected to receive the reflected wave at the distance r is expressed by the following equation (2). It is represented by
n _el = floor (θ _d /Δθ+0.5) (2)
Here, floor (a) is a function representing a maximum integer equal to or smaller than a.
Next, the expression (2) represents the delay time for receiving the reflected wave (the time difference from the transmission pulse radiation to the reception of the reflected wave) t _d , as shown in the expression (3).
n _el = floor (v _θ t _d /Δθ+0.5) (3)

An example of the light-receiving element switching timing with respect to transmission is shown in FIG. Immediately after the transmission pulse is emitted, the receiving element 0 is selected. Next, when a certain time has elapsed from the transmission pulse radiation, the receiving element 1 is selected. When a certain time further elapses, the receiving element 2 is selected. In this example, when the reception element 2 is switched, the entire reception timing is completed, and the next transmission pulse radiation is performed.
The AD conversion unit 100 converts an analog signal that is a reception signal of the light receiving element at the imaging position of the reception beam output from the light receiving element switching unit 90 into a digital signal. In this case, the AD conversion unit 100 starts AD conversion processing in synchronization with the transmission unit 20. For example, if the measurement is started from the distance 0, the AD conversion unit 100 starts sampling immediately after the emission of the transmission pulse is finished. Actually, the transmission wave may leak into the reception system immediately after the start of transmission. In order to prevent such leakage, a reflected signal reflected from a distance after a set shortest observation distance after the transmission pulse is emitted, that is, AD conversion may be performed. FIG. 3 also illustrates the AD conversion timing.

  Note that the example of FIG. 3 shows the timing when only one light receiving element is selected at a time. However, actually, the reflected light that has been formed may straddle the two light receiving elements depending on the angle between the transmission and reception. In consideration of this, the light receiving element switching unit 90 is configured to operate so as to select two light receiving elements at the same time and output the sum of reception signals obtained by both light receiving elements. That's fine. For example, as shown in FIG. 4, when an image formed by the reception beam forming unit 50 is formed across the light receiving element 0 and the light receiving element 1, the light receiving element switching unit 90 obtains the light receiving element 0 and the light receiving element 1. The sum of the received signals is output. FIG. 5 exemplifies the switching timing of the light receiving elements for the transmission at this time, but shows that the received signals obtained by the respective light receiving elements may be added for the portions where the selected time is the same.

  The signal processing unit 110 includes a detection processing unit 111 that performs detection processing on an AD-converted digital reception signal, and an angle correction unit 112 that corrects angular deviation between transmission and reception. The detection processing unit 111 performs a process of extracting only the reflected wave component from the reflection object to be observed. In addition to the reflected wave component from the reflected object to be observed, the received signal includes noise generated inside the radar apparatus and reflected waves from the reflected object that is not the observed object. For example, when the observation target is a distant terrain and there is rainfall between the radar and the terrain, a reflected wave reflected by raindrops is mixed in the received signal. In this case, since the reflected wave from the raindrop is an unnecessary component, it is removed by the detection process. For such detection processing, a well-known specific method such as CFAR (Constant False Alarm Rate) may be used. The detection processing unit 111 detects the distance and angle of the reflecting object based on the extracted reflected wave component.

Here, pulse modulation of the transmission wave will be described.
The distance r of the reflecting object is obtained from the equation (4) using the time difference t _d between the transmission time of the transmission pulse and the reception time of the reflected wave detected by the detection process.
r = ct _d / 2 (4)
Where c is the speed of light.
In general, in a radar that obtains a distance resolution by pulse-modulating a transmission wave, the distance resolution Δr is expressed by equation (5) depending on the pulse width Δt.
Δr = cΔt / 2 (5)
On the other hand, the distance section length (angle resolution) Δr ′ that can be measured from the received signal by one receiving element determined from the beam scanning speed is expressed by the following equations (1) to (6).
Δr ′ = cΔθ / 2v _θ (6)
If the receiving element is switched during reception of the reflected wave of a certain distance resolution cell, it becomes impossible to receive all of the reflected wave in the distance resolution cell, so that the strength of the received signal may be reduced. In order to solve this problem, the pulse width Δt should be set so that at least Δr <Δr ′ so that a reception signal within the distance resolution can be obtained by one receiving element.

  The direction of radiation of the transmitted beam at the time of observation is an approximate angle. However, the angle data does not take into account the deviation angle between the transmission beam and the reception beam. Therefore, the angle correction unit 112 inputs the beam scanning angle and the transmission / reception gap angle, and corrects the transmission / reception angle deviation angle for the angle data. Through the above processing, the distance of the reflecting object and the correct angle after correction are obtained, and the position of the reflecting object is measured.

In the above description, an example in which beam scanning is performed in only one direction is shown. On the other hand, when beam scanning is performed in the opposite direction, the opposite light receiving element is selected. If only one beam scanning direction is required, the position where the image is formed when the beam scanning speed is 0 may be configured to be the light receiving element at the end of the light receiving unit 60.
In the above description, the case where the beam scanning is performed only in the one-dimensional direction has been described. However, the light receiving elements are two-dimensionally arranged to perform the beam scanning in two dimensions (for example, the elevation angle and the azimuth angle). It may be.
Further, in the above description, a configuration in which the transmission beam is formed by the radiation unit 30 and the reception beam is formed by the reception beam formation unit 50 has been described. In this case, an optical mechanism having a configuration capable of forming a transmission beam and a reception beam may be used so that the radiation unit 30 and the reception beam forming unit 50 can be shared.

  As described above, according to the first embodiment, a pulse-modulated wave is transmitted as a transmission beam and transmitted by beam scanning, and a plurality of receiving elements arranged using a reception beam scanned in synchronization are scanned. The reflected wave is received by one of them, and the angle difference between the transmitted beam and the reflected wave is calculated based on the beam scanning speed and the observation distance, and an image is formed from a plurality of receiving elements according to the angle difference. Since only the selected light receiving element is selected and the received signal is obtained, the reflected wave to be observed can be received without loss even when the angle between the transmitted beam and the received beam is shifted due to the time difference between transmission and reception. It is done. Also, by correcting the angular deviation of the received beam, angle measurement can be accurately performed even when high-speed beam scanning is performed. Further, in the case of a configuration in which a plurality of light receiving elements on which the received beam is imaged at the same time are selected, if the received signals from the selected plurality of light receiving elements are added and used, it depends on the gap between transmission and reception. Therefore, it becomes possible to receive the reflected wave without loss.

Embodiment 2. FIG.
In the first embodiment, the method of selecting the light receiving element of the light receiving unit in accordance with the angular deviation between transmission and reception and performing the detection process on the selected receiving element has been described. In the second embodiment, all the light receiving elements are described. A method for selecting the detection data after performing the detection process will be described.
FIG. 6 is a block diagram showing a functional configuration of a radar apparatus according to Embodiment 2 of the present invention. In the figure, functional parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted in principle. In the second embodiment, the light receiving element switching timing generation unit 80, the light receiving element switching unit 90, the AD conversion unit 100, and the detection processing unit 111 of the first embodiment are not used, and the detection processing unit 121 and the detection data selection unit 122 are used. Newly provided.
The detection processing unit 121 detects the peak value included in each received signal obtained from all the receiving elements of the light receiving unit 60, and calculates the time when each peak value is detected based on the timing signal as the delay time. It is means to do. The detection data selection unit 122 calculates the delay calculated by the detection processing unit 121 from the transmission / reception shift angle calculated by the transmission / reception shift angle calculation unit 70 for each received signal whose peak value is detected by the detection processing unit 121. This is means for extracting a value corresponding to time, and selecting and outputting only the received signal of the light receiving element capable of receiving the reflected wave based on the extracted value of the transmission / reception gap angle.

Next, the operation will be described.
The transmission unit 20, the radiation unit 30, the beam scanning unit 40, the reception beam forming unit 50, and the light receiving unit 60 are used to radiate transmission waves in the form of beams and receive the reflected waves by the light receiving elements of the light receiving unit 60. Obtaining an electric signal having a strength corresponding to the strength is the same as the method described in the first embodiment. However, in the case of the second embodiment, all of the plurality of receiving elements of the light receiving unit 60 are configured to output respective received signals. That is, one of the plurality of receiving elements sends a reception signal of a reflected wave to the detection processing unit 121, but the other receiving elements also use reception beams directed in the direction around the arrival direction of the reflected wave. The received signal is transmitted.
Detection processing is performed by the detection processing unit 121 on electric signals generated by the respective light receiving elements of the light receiving unit 60. This detection process is assumed to be performed on an analog signal. The detection processing unit 121 detects and outputs the peak value of the included echo and the delay time at that time (ie, related to the distance of the reflecting object) for each received signal obtained by the light receiving unit 60. Therefore, the detection processing unit 121 includes a clock, and when a timing signal indicating transmission start timing is input from the control unit 10, the clock time is initialized (becomes time 0). The time when the peak value of the echo is obtained is taken as the peak delay time.

  The transmission / reception deviation angle calculation unit 70 calculates the deviation angle for each distance from the beam scanning speed according to the equation (1). In the detection data selection unit 122, the detection processing unit 121 detects based on the delay time corresponding to the transmission / reception shift angle calculated by the transmission / reception shift angle calculation unit 70 and the peak value detected by the detection processing unit 121. Select the received signal. In this selection process, attention is first focused on one of detection data (a reception signal including a peak value and its delay time) corresponding to each light receiving element output from the detection processing unit 121, and the distance included in the detection data is determined as a delay time. The transmission / reception shift angle calculated by the transmission / reception shift angle calculation unit 70 corresponding to the distance is obtained. If the obtained transmission / reception deviation angle is that of the light receiving element corresponding to the detected detection data, the received signal of the light receiving element is used as the light receiving element receiving the reflected wave from the reflecting object to be observed. Select as a signal. On the other hand, if the deviation angle between the transmission and reception at this time is not that of the light receiving element corresponding to the focused detection data, the detection data can be regarded as a false detection caused by receiver noise, and the detection data is removed . Next, the angle correction unit 112 corrects the angle of the reflection object of the reception signal selected by the detection data selection unit 122 based on the transmission / reception gap angle and the beam scanning angle obtained from the beam scanning hand unit 40. This process is the same as in the first embodiment.

  As described above, according to the second embodiment, any one of a plurality of receiving elements arranged by using a reception beam that is transmitted by scanning a pulse-modulated wave as a transmission beam and scanned in synchronization is used. In addition, the reflected wave is received, and the angle difference between the transmitted beam and the reflected wave is calculated based on the beam scanning speed and the observation distance, and according to the angle difference, the difference between the received signals of the plurality of receiving elements is calculated. Therefore, only the reception signal of the light receiving element that has received the reflected wave to be observed is selected, so even when the angle between the transmitted beam and the received beam is shifted due to the time difference between transmission and reception, the predetermined reflected wave Only the received signal can be extracted. Also, by correcting the angular deviation of the received beam, angle measurement can be accurately performed even when high-speed beam scanning is performed. Further, when the reception signals of a plurality of light receiving elements, on which the reception beam is imaged simultaneously, are selected, if the selected plurality of reception signals are added and used, the transmission / reception deviation angle is not affected. The reflected wave can be received without loss.

Embodiment 3 FIG.
In the first embodiment, the light receiving element of the light receiving unit is switched according to the distance of the reflecting object. When the actual application limits the observation distance section to a narrow range in advance, even if the light receiving element is switched according to the beam scanning speed, the light receiving element to be selected is selected during observation with the beam scanning speed being constant. Can be fixed. In the third embodiment, a processing method when the distance section is limited to a narrow range will be described.
FIG. 7 is a block diagram showing a functional configuration of a radar apparatus according to Embodiment 3 of the present invention. In the figure, functional parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted in principle. In the third embodiment, the light receiving element switching timing generation unit 80 of the first embodiment is not used, and the transmission / reception deviation angle calculated by the transmission / reception deviation angle calculating unit 70 is directly input to the light receiving element switching unit 90. I have to.

  Here, the light-receiving element switching unit 90 is directly inputted with the transmission-and-reception deviation angle calculated by the transmission-and-reception deviation angle calculating unit 70, selects only the light-receiving element at the position corresponding to the transmission-and-reception deviation angle, and receives it. Output a signal. In this case, since the observation distance section of interest is fixed to one and the transmission / reception gap angle is a single value fixed during observation, the light receiving element switching unit 90 corresponds to the transmission / reception deviation angle. It is only necessary to select the light receiving element at the position. Therefore, such a radar apparatus does not require the light receiving element switching timing generation unit 80 using the timing signal output from the control unit 10, and the configuration is simplified as compared with the case of the first embodiment. Can be reduced.

Embodiment 4 FIG.
Each of the above embodiments has been described on the assumption that the transmission beam is a beam having the same width as the reception beam. However, the case where the shapes of the transmission beam and the reception beam are set differently will be described. . A case where the reception beam width is narrower than the transmission beam width will be described.
The radar apparatus according to the fourth embodiment has the same functional configuration as that of FIG. 6 according to the second embodiment. In the reception beam forming unit 50, a reflected wave by the reflecting object obtained by scanning of the beam scanning unit 40 is shaped into a reception beam having the arrival direction, and the beam width is transmitted beam formed by the radiation unit 30. Set to be narrower than the beam width. The relationship between the shapes of the transmission beam and the reception beam at this time is as shown in FIG. 8A shows a state in the case of a short distance, FIG. 8B shows a state in a middle distance, and FIG. 8C shows a state in a long distance. In any case, the transmission beam represented by the alternate long and short dash line has a wide beam width, and the reception beam has a narrower beam width than the transmission beam. In the figure, an example in which the transmission beam has a spread corresponding to three reception beams is shown. Here, the number of light receiving elements of the light receiving unit 60 is larger than the number necessary to cover the transmission beam width (here, 3), and the coverage width of all reception beams is larger than the transmission beam width. It is configured to be wide. The beam scanning unit 40 changes the angle of the entire beam arrangement while maintaining the positional relationship between the beams.

  At a short distance in FIG. 8A, since the angle difference between the transmission and reception is small, the reflected wave is received by the three light receiving elements (solid lines) corresponding to the three central beams. The middle distance in FIG. 8B represents a situation where the angular deviation between transmission and reception is shifted by one light receiving element. Therefore, the reflected wave is received by the three light receiving elements (solid lines) positioned on the right side by one light receiving element interval as compared with FIG. At a further distance, the reflected wave is received by three light receiving elements (solid lines) positioned on the right side by one light receiving element interval as shown in FIG. 8C. However, since the detection processing unit 111 is not configured to select a light receiving element to be detected, the detection processing unit 111 performs a detection process on the reception signals of all the light receiving elements. Then, the detection data selection unit 122 selects only the reception signal of the light receiving element that has received the reflected wave to be observed, and outputs it to the angle correction unit 112.

  FIG. 9 schematically shows a state in which a received beam of reflected waves is received in a pixel pattern. This pattern represents the state before angle correction, the horizontal axis represents the angle, and the vertical axis represents the distance. The graph in the figure is divided into a grid. Each of the divided grids represents a resolution cell having a horizontal resolution as an interval between two reception beams corresponding to two adjacent light receiving elements and a vertical resolution as a distance resolution. Among the resolution cells, the hatched cells are the ones that receive the reflected light. At a short distance, the angle deviation between transmission and reception is small. Therefore, reflected light is received by the three cells in the center at each distance. It is shown that the angle shift between transmission and reception increases as the distance becomes longer, shifts to the right by one when the distance is medium, and further shifts by one when the distance is long. In this way, a reflected wave is received in which different directions are observed depending on the distance. However, since the transmission beam is actually emitted in only one direction, the apparently obtained radar image has distortion. Therefore, the angle correction unit 112 corrects the reception area obtained as shown in FIG. 9 to have the pixel pattern of FIG.

  As described above, according to the fourth embodiment, a plurality of light receiving elements that make a transmission beam wider than a reception beam and cover a wider range than the transmission beam spread for a narrow reception beam. Because the reflected wave is received by this method, the angle measurement is accurate even when high-speed beam scanning is performed by correcting the angle deviation of the received signal of the reflected wave, and an image without distortion can be obtained. Can do. Note that the fourth embodiment has been described by taking the case where it is applied to the configuration of the radar apparatus of the second embodiment as an example, but can also be applied to the configuration of the first embodiment.

In each of the embodiments described above, the invention has been described by taking a radar apparatus using laser light as a pulse-modulated wave as an example. However, the invention is also applicable to an apparatus using a wave such as a radio wave or a sound wave. It can be applied to the above and has the same effect.
For example, when radio waves are used, the radiation unit 30 uses a commonly used radar antenna such as a reflector antenna or a lens antenna, and the reception beam forming unit 50 also uses the same radar antenna as a reception antenna. The receiving unit (corresponding to the light receiving unit 60) is realized by arranging a plurality of primary radiators of the receiving antenna at different positions. The beam scanning unit 40 is realized by a driving mechanism that mechanically rotates the radiation unit 30, the reception beam forming unit 50, and the entire reception unit (corresponding to the light receiving unit 60). In addition, when the whole radar apparatus is reduced in size by using a millimeter wave band as a transmission wave, a driving mechanism that mechanically rotates the entire radar apparatus may be considered.
Further, even when sound waves are used, the radiation unit 30 and the reception beam forming unit 50 can be realized by a parabolic reflector, for example. The receiving unit (corresponding to the light receiving unit 60) is realized by a plurality of microphones arranged at different positions near the focal point of the parabolic reflector serving as the receiving beam forming unit 50. The beam scanning unit 40 is realized by a drive mechanism that mechanically rotates the entire radiation unit 30, reception beam forming unit 50, reception unit (equivalent to the light receiving unit 60), or a drive mechanism that mechanically rotates the entire radar apparatus. Is done.

It is a block diagram which shows the function structure of the radar apparatus by Embodiment 1 of this invention. It is explanatory drawing which represented typically the image formation state to the light receiving element with respect to the receiving beam direction which concerns on Embodiment 1 of this invention. It is explanatory drawing showing the example of the switching timing of the light receiving element with respect to transmission based on Embodiment 1 of this invention. It is explanatory drawing which represented typically the image formation state over two light receiving elements which concern on Embodiment 1 of this invention. It is explanatory drawing showing another example of the switching timing of the light receiving element with respect to transmission which concerns on Embodiment 1 of this invention. It is a block diagram which shows the function structure of the radar apparatus by Embodiment 2 of this invention. It is a block diagram which shows the function structure of the radar apparatus by Embodiment 3 of this invention. It is explanatory drawing showing the relationship of the shape of the transmission / reception beam which concerns on Embodiment 4 of this invention. It is the schematic diagram which represented the state in which the received beam of the reflected wave which concerns on Embodiment 4 of this invention was received with the pixel pattern. It is the schematic diagram which represented the state after the angle correction which concerns on Embodiment 4 of this invention with the pixel pattern.

Explanation of symbols

  20 transmitting unit, 30 emitting unit, 40 beam scanning unit, 50 receiving beam forming unit, 60 light receiving unit (receiving unit), 70 transmission / reception shift angle calculating unit, 80 light receiving element switching timing generating unit (receiving element switching timing generating unit) , 90 light receiving element switching unit (receiving element switching means), 100 AD conversion unit, 111 detection processing unit, 112 angle correction unit, 121 detection processing unit, 122 detection data selection unit.

Claims (9)

In a radar apparatus that measures data on a reflective object by radiating a wave in space and receiving a wave reflected by a reflective object existing in the space,
Transmitting means for generating a pulse-modulated wave based on a reference timing signal;
Radiation means for shaping the generated wave into a transmission beam and radiating it into space;
Beam scanning means for scanning the transmission beam and the reception beam at the same beam scanning speed and in the same direction or close to each other in accordance with a predetermined beam scanning speed and scanning direction instruction;
Receiving beam forming means for capturing only waves coming from a specific direction from space and outputting the waves;
Using the shaped reception beam, receiving means for receiving a reflected wave by any of a plurality of arranged receiving elements and obtaining a received signal;
Based on the predetermined beam scanning speed and a plurality of assumed reflecting object distances, the angle of beam scanning by the beam scanning means in the time from transmission to reception is set as the deviation angle between transmission and reception for each distance of the reflecting object. A transmission / reception gap angle calculating means for calculating
Receiving element switching timing generating means for generating a switching timing for selecting a receiving element at a position where the reflected wave can be received based on the timing signal and the calculated transmission-reception gap angle;
In accordance with the generated switching timing, receiving element switching means for selecting only a receiving element at a position where the reflected wave can be received from the plurality of receiving elements and outputting a reception signal of the selected receiving element. A radar apparatus comprising: AD conversion means for digitally converting the received signal output from the receiving element switching means;
A detection processing means for extracting only the reflected wave component from the reflected object to be observed from the digitally converted received signal, and detecting the distance and angle of the reflected object based on the extracted reflected wave component;
2. The radar according to claim 1, further comprising angle correction means for correcting the angle of the reflecting object obtained by the detection processing means based on a transmission / reception gap angle and a beam scanning angle obtained from the beam scanning means. apparatus.   The receiving element switching means, when a plurality of receiving elements at a position for receiving a receiving beam are selected, adds and outputs the received signals of the selected plurality of receiving elements. Item 3. The radar device according to item 2. In a radar apparatus that measures data on a reflective object by radiating a wave in space and receiving a wave reflected by a reflective object existing in the space,
Transmitting means for generating a pulse-modulated wave based on a reference timing signal;
Radiation means for shaping the generated wave into a transmission beam and radiating it into space;
Beam scanning means for scanning the transmission beam and the reception beam at the same beam scanning speed and in the same direction or close to each other in accordance with a predetermined beam scanning speed and scanning direction instruction;
Receiving beam forming means for capturing only waves coming from a specific direction from space and outputting the waves;
Using the shaped reception beam, receiving means for receiving a reflected wave by any of a plurality of arranged receiving elements and obtaining a received signal;
Based on the predetermined beam scanning speed and a plurality of assumed reflecting object distances, the angle of beam scanning by the beam scanning means in the time from transmission to reception is set as the deviation angle between transmission and reception for each distance of the reflecting object. A transmission / reception gap angle calculating means for calculating
Detection processing means for detecting a peak value included in each received signal obtained from all the plurality of receiving elements, and calculating a time when each peak value is detected based on the timing signal as a delay time;
For each received signal for which the peak value is detected by the detection processing means, a value corresponding to the calculated delay time is extracted from the calculated transmission / reception deviation angle, and the extracted transmission / reception deviation angle value is obtained. A radar apparatus comprising: a detection data selection unit that selects and outputs only a reception signal of a reception element capable of receiving a reflected wave from reception signals of the plurality of reception elements.   5. An angle correction means for correcting the angle of the reflecting object in the received signal selected by the detection data selection means based on the transmission / reception gap angle and the beam scanning angle obtained from the beam scanning means. The radar apparatus described.   6. The detection data selecting means, when a plurality of reception signals of a receiving element that has received a reception beam are selected, adds the selected plurality of reception signals and outputs the sum. The radar apparatus described.   The pulse width for performing pulse modulation in the transmission means is set so that the distance resolution determined by pulse modulating the transmission wave is smaller than the distance section length measurable by one receiving element determined from the beam scanning speed. The radar apparatus according to any one of claims 1 to 6, wherein the radar apparatus is characterized in that:   Instead of using the receiving element switching timing from the receiving element switching timing generating means, the receiving element switching means fixes one observation distance section of interest by fixing one observation distance interval calculated by the sending / receiving gap angle calculating means. 4. The radar device according to claim 1, wherein only a receiving element at a position corresponding to the gap between transmission and reception is selected based on the deviation angle. 5. The reception beam forming means sets the beam width of the reception beam to be formed narrower than the beam width of the transmission beam formed by the radiation means,
The receiving means is provided with an array of receiving elements so that a range in which the coverage areas of the plurality of receiving beams corresponding to the predetermined plurality of receiving elements are combined is wider than the transmission beam, and the reflected wave from the reflecting object is generated. 5. The radar apparatus according to claim 1, wherein reception is performed by the predetermined plurality of receiving elements.

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