JPH1164500A - Radar equipment - Google Patents

Abstract

(57) [Problem] To provide a radar apparatus capable of accurately determining the direction of a target even when a target such as a preceding vehicle is positioned at an end of a radar beam scanning range. SOLUTION: An FM-modulated radar signal is emitted from a transmission / reception antenna 27 while scanning the beam direction with a predetermined beam, and a reflection signal from a target and a part of a transmission signal are mixed by a mixing unit 25. A beat signal 25a is obtained. The effective reflection cross-section calculation unit 33 calculates the effective reflection cutoff based on the reception level when the beam center is irradiated on the target, the antenna gain value at the beam center, and the detected distance to the target. Find the area. The azimuth calculation unit 32 calculates the antenna gain from the received signal level if the target exists slightly outside the scanning range of the radar beam and the effective reflection cross section of the target is known. Then, the azimuth of the target is obtained from the angle-gain characteristics of the radar beam registered in advance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar device,
In particular, the present invention relates to a radar device capable of detecting a direction of a target in a wide range.

[0002]

2. Description of the Related Art The present applicant discloses in Japanese Patent Application Laid-Open No. Hei 6-242230 that one of a plurality of antennas arranged so as to radiate beams having substantially the same radiation pattern while partially overlapping each other. By receiving radio waves with other antennas, by realizing the same function as adding one virtual antenna between adjacent antennas,
We propose a time-division radar system that can achieve high detection accuracy and a wide detection angle range with a limited number of antennas. When reflected waves from a target are received by a plurality of adjacent antennas, the level of each direction is weighted and averaged to detect the direction of the target that caused the reflected wave with high accuracy. be able to.

[0003] The present applicant has disclosed in Japanese Patent Application Laid-Open No. 8-13664.
No. 7, in the FM-CW multi-beam radar apparatus in which a beam transmitting / receiving means for emitting a beam and receiving a signal reflected by the target is arranged so that a part of the beam overlaps each other, when detecting a target. Transmit a beam using one of the beam transmitting and receiving means arranged so that a part of the beam overlaps each other, and receive using a beam transmitting and receiving means arranged so that a part of the beam overlaps each other. Radar system that performs

[0004] The applicant of the present invention has disclosed Japanese Patent Application Laid-open No. Hei 7-31863.
No. 5, multi-beam transmission / reception means, reception level storage means for detecting the intensity of a reflected wave from a target received by each transmission / reception channel and the distance to the target, and sequentially storing the detected level,
A multi-beam pattern storage means for previously creating and storing a multi-beam pattern matrix in which the square of the directivity of each transmission beam is arranged in a matrix corresponding to each transmission / reception channel or its inverse matrix, and storing and storing the same. The reception level of each transmission / reception channel is corrected by arranging reception levels having substantially the same distance in rows or columns corresponding to transmission / reception channels and performing an arithmetic process based on a matrix of a multi-beam pattern or its inverse matrix. There has been proposed a multi-beam radar apparatus that includes an inverse operation means for calculating a value so that a large number of reflection sources distributed in a two-dimensional space can be detected with high resolution by deconvolution processing.

[0005] Further, the present applicant has disclosed in Japanese Patent Application Laid-Open No. Hei 5-28883.
In Japanese Patent Application Publication No. 8 (1996), by calculating target data for each reflection signal received within a certain sampling time and labeling the target data, a relative speed between a plurality of targets is obtained. The proposed relative speed estimation method is proposed.

[0006]

Conventionally, the lateral position (detection angle) of an obstacle detected by a multi-beam radar or the like is determined by an amplitude angle conversion method or a center of gravity calculation method (Japanese Unexamined Patent Publication No.
242230). In principle, these methods calculate the lateral position from the amplitude of the beam surrounding the obstacle, so if the obstacle (target) is located outside the center of the end beam, There was a problem that the horizontal position could not be calculated.

The present invention has been made to solve such a problem, and provides a radar apparatus capable of accurately obtaining the position (direction) of a target even when the target is located at the end of a beam. The purpose is to:

[0008]

A radar device according to the present invention transmits and receives a radar signal and receives a radar signal reflected by a target, and determines a relative distance to the target based on the received signal. A distance detection unit for detecting, an effective reflection cross-section calculation unit for obtaining an effective reflection cross-sectional area of the target based on the relative distance and the received signal level, and a target for which the effective reflection cross-section is obtained is an end of the radar beam. And an azimuth calculation unit for obtaining the azimuth of the target based on the angle-gain characteristics of the radar beam registered in advance, the relative distance to the target, and the received signal level.

[0009] The effective reflection cross-sectional area calculation unit determines the effective reflection cross-sectional area of the target based on the detected distance to the target and the level of the received signal. The azimuth calculation unit, when the target for which the effective reflection cross section is obtained is located at the end of the radar beam,
The azimuth of the target is obtained based on the gain characteristics of the radar beam pattern registered in advance, the distance to the detected target, and the received signal level.

When a target exists slightly outside the scanning range of the radar beam, the antenna gain can be obtained from the received signal level if the effective reflection cross-sectional area of the target is known. Then, the azimuth of the target can be specified from the obtained antenna gain and the gain characteristics of the radar beam pattern registered in advance.

In the radar device according to the present invention, the transmitting / receiving section includes a plurality of transmitting / receiving antennas. When detecting a target, the transmitting / receiving section uses one of the transmitting / receiving antennas arranged so that a part of the beams overlap with each other. Japanese Patent Laid-Open Publication No. Hei 8-
It may be used in a bistatic antenna mode as disclosed in JP-B-136647. By making the antenna that transmits the beam and the antenna that receives the beam different, noise can be reduced, the received signal level can be made more accurate, and the azimuth of the target can be detected more accurately.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram of a radar beam scanning type FM-CW radar apparatus according to the present invention. This radar beam scanning type FM-CW radar device 1
Includes a transmission / reception unit 2 and a signal processing unit 3.

The transmission / reception unit 2 includes a sweep / scan control unit 21 and
It includes an FM signal generator 22, a power distributor 23, a circulator 24, a mixer 25, an antenna coupler 26, a transmitting / receiving antenna 27, an antenna driver 28, and an angle signal generator 29.

As shown in FIG. 2A, the sweep / scan control unit 21 generates a transmission frequency designation voltage signal (modulation signal) 21a having a triangular waveform in a predetermined sweep cycle T. The transmission frequency designation voltage signal 21a is supplied to the FM signal generator 22.

The FM signal generator 22 includes a voltage controlled oscillator for generating a high frequency signal in a quasi-millimeter wave band or a millimeter wave band. For example, it may be configured to include a voltage-controlled oscillator that generates a high-frequency signal of 30 to 150 GHz. The FM signal generator 22 includes a transmission frequency designating voltage signal (modulation signal) 21a.
, An FM signal 22a whose frequency changes at a predetermined sweep cycle T is generated as shown in FIG. FM
The signal 22a is supplied to the power distributor 23.

The power distributor 23 distributes the FM signal 22a into a transmission signal 23a and a local oscillation signal 23b. The transmission signal 23a is supplied to the circulator 24. The local oscillation signal 23b is supplied to the mixing unit 25.

The circulator 24 supplies the transmission signal 23a to the transmission / reception antenna 27 via the antenna coupling section 26. As a result, the FM-modulated radar signal (radar radio wave, radar beam) is transmitted from the transmitting / receiving antenna 27. The received signal of the reflected wave reflected by the target and returned to the transmission / reception antenna 27 is supplied to the circulator 24 via the antenna coupling unit 26. Circulator 24
Separates the received signal and supplies the separated received signal 24a to the mixing unit 25.

The mixing section 25 mixes the received signal 24a and the local oscillation signal 23b, and outputs a signal having a frequency difference between the frequency of the received signal 24a and the frequency of the local oscillation signal 23b as a beat signal 25a. The beat signal 25a is supplied to the signal processing unit 3.

The antenna coupling section 26 is formed using a rotary joint or a flexible waveguide.

As the transmitting / receiving antenna 27, one having a predetermined beam width (transmitting a radar beam having a predetermined beam width) is used. An example of the antenna gain (directivity) of the transmitting / receiving antenna 27 is shown in FIG. It is an example of the angle-gain characteristic about a radar beam.

The antenna driving section 28 swings the transmitting / receiving antenna 27 within a predetermined scanning angle range based on the scan permission signal 21b supplied from the sweep / scan control section 21. FIG. 4 shows an example of the radar beam scanning range.

The angle signal generator 29 is provided with the transmitting / receiving antenna 2
7, and outputs an angle signal 29a indicating the radiation direction of the beam center of the transmitting / receiving antenna 27. The angle signal 29a is supplied to the signal processing unit 3.

As shown in FIG. 2 (c), the sweep / scan control unit 2 switches the frequency of the FM signal 3a from the frequency-up sweep to the frequency-down sweep, and the frequency-down sweep from the frequency-down sweep. During a period until a predetermined time D elapses from the time point when the sweep is switched to the up position, the scan permission signal 21b for disabling the antenna scan is output. The time D during which the scanning of the antenna is not permitted is set according to the maximum detection distance of the radar device. For example, when the maximum detection distance is set to 150 meters, the transmission wave becomes 15
It is set to a time longer than 1 microsecond until it returns after being reflected by the target 0 meters away. During the period in which the beat signal between the reflected signal (reception signal) of the sweep whose frequency increases and the transmission signal of the sweep whose frequency decreases, the beat signal indicating the relative distance to the target cannot be obtained,
During a period in which a beat signal indicating the relative distance is not obtained, the scanning of the antenna is stopped.

The antenna driving section 28 shown in FIG. 1 includes a motor, a gear mechanism, and the like. The antenna driving unit 28 swings the transmission / reception antenna 27 while the scanning permission signal 21b is supplied (in a permission state), and transmits and receives the transmission / reception antenna 2 while the scanning permission signal 21b is not supplied (in a non-permission state).
7 is stopped, and the orientation of the antenna at that time is maintained. The antenna may be rotated by a predetermined angle at a time during which one scan permission signal is supplied.

Note that the antenna driving section 28 supplies the scanning permission signal 21b every time the scanning permission signal 21b is supplied.
The antenna may be rotated by a predetermined angle each time is supplied a predetermined number of times. For example, every time the scanning permission signal 21b is supplied twice, the direction of the antenna is shifted, for example, by one degree, so that the object is subjected to both frequency-up sweep and frequency-down sweep in the same direction. Detection becomes possible. By performing both frequency-up and frequency-down sweeps in the same direction, and measuring the frequency of the beat signal for each sweep, the relative distance to the target and the relative speed of the target can be determined. it can.

In addition, the period during which a beat signal indicating the relative distance to the target is not obtained is sufficiently short as compared with the rotation speed (scanning speed) of the antenna, and the angle range over which the target cannot be detected is extremely narrow and substantially. If the blind angle range does not occur, the antenna may be swung (scanned) regardless of the sweep timing of the FM signal 22a.

The signal processing section 3 includes a distance detecting section 31, an azimuth calculating section 32, an effective reflection cross section calculating section 33, and a target tracking section 34. The signal processing unit 3 may include a CPU, a ROM, and a RAM, or may include a DSP (digital signal processor).

The distance detector 31 analyzes the frequency spectrum of the beat signal 25a and detects the relative distance from the frequency of the beat signal 25a to a target. The distance detection unit 31 supplies information on the detected relative distance to the target tracking unit 34.

The azimuth calculation unit 32 sets the scanning angle of the antenna at which the signal level (beat signal level) of the frequency corresponding to the detected relative distance to the target becomes the maximum as the azimuth angle of the target. The azimuth calculation unit 32 supplies the target tracking unit 34 with information on the azimuth of the detected target and information on the level of the beat signal when the azimuth is determined.

The target tracking unit 34 labels the detected target, and stores the detected time, the relative distance to the target, the signal level, and the azimuth of the target in association with each other. When the target is detected by the next beam scanning, the target tracking unit 34 performs collation with the data of the already detected target. The target tracking unit 34
As a result of the collation, when it is determined that the target is the same target, the time detected by the label name given earlier, the relative distance to the target, the signal level, and the direction of the target are stored in association with each other.

The effective reflection cross section calculating section 33 calculates the effective reflection cross section of the target based on the data on the detected target stored in the target tracking section 34. The effective reflection cross section calculation unit 33 obtains the reception power of the reflection signal from the target received by the transmission / reception antenna 27 based on the level of the beat signal stored in the target tracking unit 34. In the effective reflection cross section calculation unit 33, data of the mixing gain of the mixing unit 25, the loss of the received signal in the circulator 24, and the loss in the antenna coupling unit 26 are registered in advance in an internal memory or the like. The antenna gain of the transmission / reception antenna 27 is registered in the internal memory or the like in the effective reflection cross section calculation unit 33.

The effective reflection cross section calculator 33 calculates the effective reflection cross section based on the radar equation shown in Equation 1.

[0033]

(Equation 1)

In equation (1), Pr is reception power (unit: milliwatt), Pt is transmission power (unit: milliwatt), G is antenna gain (unit: decibel), λ is transmission wavelength (unit: meter), θ is effective reflection cross section (unit: Unit: decibels / square meter), h: ground height of the transmitting / receiving antenna (unit: meter), ht: ground height of the target (unit: meter), R: distance to the target (unit: meter), F: propagation loss (unit: decibel) , L is the circuit loss (in decibels).

Transmission power Pt of FM-CW radar device 1
Is constant. The transmission power Pt is registered in advance in the effective reflection area calculating unit 33. The transmission wavelength λ is registered in advance in the effective reflection sectional area calculation unit 33. The ground height h of the transmitting / receiving antenna is registered in advance in the effective reflection area calculating unit 33. When the transmission / reception antenna 27 is provided with a radome, a loss value due to the radome is registered in advance as a propagation loss F. A predetermined value is registered in advance as the circuit loss L.

When two sets of data having different detection distances for the same target are stored in the target tracking section 34, the effective reflection cross section calculation section 33 substitutes the respective distances and the reception power at each distance. By creating these two radar equations and solving the two radar equations as simultaneous equations, the effective reflection cross section θ of the target and the ground height ht of the target are obtained. At this time, the antenna gain uses the gain value at the beam center. The obtained effective reflection cross-sectional area θ of the target and the ground height ht of the target are stored in the target tracking unit 34 in association with the label of the target.

The effective reflection cross section computing unit 33 does not calculate the effective reflection cross section θ of the target and the ground height ht of the target, but obtains the product of the effective reflection cross section θ and the ground height ht ( θ · ht) may be obtained. in this case,
This eliminates the need for two sets of data with different detection distances for the same target. When two sets of data having different detection distances are not obtained for the same target, the effective reflection cross-sectional area calculation unit 33 sets the ground height ht of the target to, for example, the average ground height of a license plate of a passenger car. Assuming that the effective reflection sectional area θ of the target may be obtained.

The azimuth calculation unit 32 recognizes that the radar beam is at the end of the scanning range based on the angle signal 29a supplied from the angle signal generation unit 29, and reflects the beam from the target with the end beam. When the signal is received, it is determined with reference to the target data stored in the target tracking unit 34 whether the target received by the end beam is a detected target. The azimuth calculation unit 32 determines that the already labeled target has been received by the end beam.
The effective reflection cross section θ and the target height ht that have already been obtained
And the received power received by the end beam is substituted into the radar equation shown in Equation 1 to obtain an antenna gain. The azimuth calculation unit 32 obtains the azimuth of the target from the obtained antenna gain and the antenna gain pattern of the end beam (see FIG. 3).

The target tracking section 34 outputs data such as the detected distance and direction of the target, the relative speed of the target, and the moving direction of the target.

When, for example, the preceding vehicle A exists inside the scanning range shown in FIG. 4, the power of the reflected signal (reception power) is obtained in a state where the center of the radar beam is radiated toward the preceding vehicle A.
Is the largest. The azimuth calculation unit 32 detects, as the azimuth of the preceding vehicle A, the angle at which the power (reception power) of the reflected signal from the preceding vehicle A becomes maximum based on the level of the beat signal 25a.

The effective reflection cross section computing section 33 calculates the effective reflection cross section θ and height ht of the preceding vehicle A based on the distance to the preceding vehicle A and the power of the reflected signal (reception power). When the position of the leading vehicle A is outside the end beam in the scanning range, the azimuth calculation unit 32 determines the received power of the end beam and the effective reflection cross-sectional area θ of the leading vehicle A that has already been obtained and the height. From the value ht, the antenna gain of the end beam is obtained. Then, the azimuth of the preceding vehicle A is obtained from the obtained antenna gain and the antenna gain characteristics shown in FIG. Therefore, even when the leading vehicle A slightly deviates outside the scanning range, the direction of the leading vehicle A can be detected.

Based on the reception level and distance when the leading vehicle A is captured at the center of the beam, the leading vehicle A is captured at the center of the beam from the distance to the preceding vehicle A detected by the end beam. Of the preceding vehicle A from the calculated level and the gain characteristic of the antenna pattern.
May be obtained.

FIG. 5 shows a multi-beam type FM according to the present invention.
FIG. 3 is a block diagram of a CW radar device. The multi-beam FM-CW radar device 11 according to the present invention includes a transmitting / receiving unit 12 and a signal processing unit 13.

The transmission / reception unit 12 includes a sweep / scan control unit 41
, An FM signal generator 42, a power divider 43, a transmission channel switch 44, a mixer 45, a receive channel switch 46, and circulators 47a to 47c for a plurality of channels.
7i and transmitting / receiving antennas 48a to 48 for a plurality of channels.
i.

FIG. 6 is an explanatory diagram showing the radiation direction of the beam. As shown in FIG.
8i is the same radiation pattern (beam pattern)
So that adjacent radiation patterns partially overlap each other. In FIG. 6, the beam pattern of the antenna 48a is shown as Ba, and the beam pattern of the antenna 48i is shown as Bi.

As shown in FIG. 2A, the sweep / scan control unit 41 generates a transmission frequency specifying voltage signal (modulation signal) 41a whose voltage waveform becomes a triangular waveform at a predetermined sweep cycle T. The transmission frequency designation voltage signal 41a is supplied to the FM signal generator 42.

The FM signal generator 42 includes a voltage-controlled oscillator that generates a quasi-millimeter wave band or a millimeter wave band high frequency signal. The FM signal generator 42, based on the transmission frequency designating voltage signal (modulation signal) 41a, as shown in FIG. 2B, changes the frequency of the FM signal 42 at a predetermined sweep period T.
generates a. The FM signal 42a is supplied to the power distributor 43.

The power distributor 43 distributes the FM signal 42a into a transmission signal 43a and a local oscillation signal 43b. The transmission signal 43a is supplied to the transmission channel switching unit 44. Local oscillation signal 43b is supplied to mixing section 45.

The sweep / scan control unit 41 specifies a transmission channel by supplying a transmission channel designation signal 41 T to the transmission channel switching unit 44. Thereby, the power distributor 4
The antenna (transmitting / receiving antenna) 48 of the designated transmission channel is transmitted via the circulator 47n (n = a to i) of the designated transmission channel in which the transmission signal 43a distributed in 3 is transmitted.
n and a radar beam is emitted. The sweep / scan control unit 41 specifies a reception channel by supplying a reception channel designation signal 41R to the reception channel switching unit 46. As a result, the antenna 4 of the designated reception channel
The signal received at 8n is separated by the circulator 47n of the designated channel and supplied to the mixing unit 45 via the reception channel switching unit 46.

The sweep / scan control section 41 includes an antenna 48a
The beam direction of the antenna 48a is scanned by designating the same antenna transmission / reception mode (monostatic antenna mode) for transmitting at the same time and receiving at the same antenna. Next, by specifying a bistatic antenna mode for transmitting by the antenna 48a and receiving by the adjacent antenna 48b, scanning is performed in a direction intermediate between the beam direction of the antenna 48a and the beam direction of the antenna 48b. Next, the beam direction of the antenna 48b is scanned by designating a mode in which transmission and reception are performed by the antenna 48b. Next, the beam direction is sequentially scanned by sequentially repeating the designation of the mode of transmitting by the antenna 48b and receiving by the adjacent antenna 48c.

The mixing section 45 mixes the reception signal 46a supplied from the reception channel switching section 46 and the local oscillation signal 43b, and adjusts the frequency of the reception signal 46a and the local oscillation signal 43b.
A signal having a frequency different from the frequency b is output as a beat signal 45a. Beat signal 45 output from the mixing unit 45
a is supplied to the signal processing unit 13. The transmission channel designation signal 41T and the reception channel designation signal 41R are also supplied to the signal processing unit 13.

The signal processing section 13 includes a distance detecting section 51, an azimuth calculating section 52, an effective reflection cross section calculating section 53, and a target tracking section 54.

The distance detecting section 51 analyzes the frequency spectrum of the beat signal 45a and detects the relative distance from the frequency of the beat signal to the target. The distance detecting section 51 outputs information on the detected relative distance to the target tracking section 5.
4

The azimuth calculation unit 52 recognizes the scanning direction of the radar beam based on the transmission channel designation signal 41T and the reception channel designation signal 41R supplied from the transmission / reception unit 12. The azimuth calculation unit 52 temporarily stores the scanning direction (scanning angle) of the recognized radar beam and the signal level of the frequency corresponding to the relative distance to the detected target. The azimuth calculation unit 52 includes a plurality of adjacent scanning directions (scanning angles).
When the target is detected in each scanning direction (scan angle)
The weight of the beat signal level (the signal level of the frequency corresponding to the distance to the target) in the above is weighted and averaged to obtain the direction of the target that has caused the reflected wave.

The azimuth calculation unit 52 determines whether a reflected signal from a target is detected by any of the beams Bb to Bh other than the beams Ba and Bi at both ends shown in FIG. If the reflected signal is detected at a high level, and if the level detected at one of the adjacent beams is extremely low with respect to the level detected at one of the beams, the reflected signal is set at a high level. It is determined that the center of the detected beam is irradiating the target, and the reception level at that time is supplied to the target tracking unit 54 and stored.

The target tracking section 54 labels the detected target, and stores the detected time, the relative distance to the target, the signal level, and the azimuth of the target in association with each other. When the target is detected by the next beam scanning, the target tracking unit 54 performs collation with the data of the already detected target. The target tracking unit 54
As a result of the collation, when it is determined that they are the same target, the time detected by the label name given earlier, the relative distance to the target, the signal level, and the direction of the target are stored in association with each other.

The effective reflection cross section calculating section 53 calculates the effective reflection cross section of the target based on the data on the detected target stored in the target tracking section 54. The effective reflection cross-section calculation unit 53 obtains the reception power of the reflection signal from the target received by the transmission / reception antenna 48n based on the beat signal level stored in the target tracking unit 54. In the effective reflection area calculating unit 53, data of the mixing gain of the mixing unit 45, the loss of the reception signal in the circulator 47n, and the loss in the reception channel switching unit 46 are registered in advance. Further, the effective reflection cross section calculation unit 33 registers the antenna gain of the transmission / reception antenna 48n.

The effective reflection cross section calculator 53 calculates the effective reflection cross section based on the radar equation shown in Equation 1. Note that the transmission power Pt of the FM-CW radar device 11 is constant, and the transmission power Pt is registered in the effective reflection cross-sectional area calculation unit 53 in advance. The transmission wavelength λ and the ground height h of the transmission / reception antenna are also registered in the effective reflection area calculating unit 33 in advance. When the transmission / reception antenna 27 is provided with a radome, a loss value due to the radome is registered in advance as a propagation loss F. A predetermined value is registered in advance as the circuit loss L.

When two sets of data having different detection distances for the same target are stored in the target tracking section 54, the effective reflection area calculating section 53 substitutes the respective distances and the reception power at the respective distances. By creating these two radar equations and solving the two radar equations as simultaneous equations, the effective reflection cross section θ of the target and the ground height ht of the target are obtained. The obtained effective reflection cross-sectional area θ of the target and the ground height ht of the target are stored in the target tracking unit 54 in association with the label of the target.

Note that the effective reflection cross section computing unit 53 does not calculate the effective reflection cross section θ of the target and the ground height ht of the target, but calculates the product of the effective reflection cross section θ and the ground height ht ( θ · ht) may be obtained. in this case,
This eliminates the need for two sets of data with different detection distances for the same target. When two sets of data having different detection distances are not obtained for the same target, the effective reflection cross-sectional area calculation unit 53 sets the ground height ht of the target to, for example, the average ground height of a license plate of a passenger car. Assuming that the effective reflection sectional area θ of the target may be obtained.

When there is no data in a state where the target is irradiated with the center of the beam, the effective reflection cross-sectional area calculation unit 53 determines the highest reception level based on the target direction obtained by the weighted averaging process. The antenna gain at the angle corresponding to the azimuth of the target in the beam for which is obtained may be obtained, and the effective reflection sectional area θ of the target may be obtained using the obtained antenna gain.

The azimuth calculation unit 52 converts the radar beam into the end beam (Ba or Bi) shown in FIG. 6 based on the transmission channel designation signal 41T and the reception channel designation signal 41R.
And if the reflected signal from the target is received in the end beam, the target tracking unit 54
It is determined whether the target received by the end beam is a detected target by referring to the target data stored in the target. When the target already labeled is received by the end beam, the azimuth calculation unit 52 receives the effective reflection cross-sectional area θ, the height ht of the target, and the end beam already obtained. The antenna gain is obtained by substituting the received power into the radar equation shown in Equation 1. Then, the azimuth calculation unit 52 obtains the azimuth of the target from the obtained antenna gain and the antenna gain pattern of the end beam.

The target tracking section 34 outputs data such as the detected distance / azimuth of the target, the relative speed of the target, and the moving direction of the target.

The radar device according to the present invention can be applied to a pulse type radar. In the case of the pulse type radar, the distance detection unit obtains the distance to the target based on the time difference between the transmission signal and the reception signal. Further, the radar device according to the present invention can be applied to a radar using light other than radio waves.

Further, in the radar apparatus according to the present invention, when the effective reflection area θ of the target to be detected has already been obtained, the reception level of the reflected signal from the target and the detected level of the reflection target θ are determined. Since the antenna gain in the direction in which the target is directed can be obtained from the relative distance and the azimuth of the target can be obtained from the obtained antenna gain, a large number of beams are overlapped with adjacent beams as shown in FIG. , For example, beams Ba, Bc, Be, B
The azimuth of a target located between beams can be accurately obtained with a smaller beam arrangement such as g and Bi.

The signal processing section 3 shown in FIG. 1 may include a sweep / scan control section 21. Signal processing unit 13 in FIG.
May include a sweep / scan control unit 41. Further, the above embodiment is an example of the present invention, and the present invention is not limited to the above embodiment.

[0067]

As described above, according to the radar apparatus of the present invention, when the target for which the effective reflection cross section is obtained is located at the end of the radar beam, the angle-gain of the radar beam registered in advance is obtained. Since the azimuth calculation unit for obtaining the azimuth of the target based on the characteristics, the relative distance to the target, and the received signal level (for example, the beat signal level) is provided, the target is slightly outside the scanning range of the radar beam. Even if the target exists, if the effective reflection cross section of the target is known, the antenna gain is obtained from the received signal level, and the target antenna is obtained from the obtained antenna gain and the angle-gain characteristics of the radar beam registered in advance. The direction can be specified. Therefore, even in a limited scanning range, the azimuth of the target can be detected over a wider range than the scanning range.

[Brief description of the drawings]

FIG. 1 is a simplified block diagram of a radar beam scanning type FM-CW radar device according to the present invention.

FIG. 2 is a waveform diagram of a transmission frequency designating voltage signal, an FM signal, and a scan enable signal.

FIG. 3 is a graph showing the antenna gain (directivity) of a transmission / reception antenna;

FIG. 4 is a simplified explanatory diagram showing an example of a scanning range of a radar beam.

FIG. 5 is a simplified block diagram of a multi-beam FM-CW radar device according to the present invention.

FIG. 6 is a simplified explanatory diagram showing a beam radiation direction of the multi-beam FM-CW radar device shown in FIG.

[Explanation of symbols]

1,11 ... Radar device, 2,12 ... Transceiving unit, 3,13
... Signal processing units, 27,48a to 48i ... Transceiver antennas, 31,51 ... Distance detectors, 32,52 ... Azimuth calculators, 33,53 ... Effective reflection area calculators, 34,54 ...
Target tracking unit.

Claims (2)

[Claims] 1. A transmitter / receiver for transmitting a radar signal and receiving a radar signal reflected by a target, a distance detector for detecting a relative distance to the target based on the received signal, a relative distance and a received signal An effective reflection cross section calculating unit for calculating an effective reflection cross section of the target based on the level; and, when the target for which the effective reflection cross section is obtained is located at an end of the radar beam, the radar beam registered in advance. And a azimuth calculating unit for obtaining the azimuth of the target based on the angle-gain characteristic, the relative distance to the target, and the received signal level. 2. The transmitting / receiving unit includes a plurality of transmitting / receiving antennas,
When detecting a target, a beam is transmitted using one transmitting / receiving antenna arranged so that a part of the beam is overlapped with another, and the other transmitting / receiving antenna is arranged such that a part of the beam is overlapped with each other The radar apparatus according to claim 1, wherein reception is performed by using a radar.