JP2000193738A - Radar device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect a target without changing the frequency of a transmission beam in a digital beam forming system radar device. SOLUTION: A phase shifter 20 is provided corresponding to each of a plurality of element antennas 28, and an irradiation direction is successively changed to a plurality of directions for transmitting a transmission beam. An A/D converter 36 is provided corresponding to each of a plurality of the element antennas 28. A beam former 38 is provided, where the beam former receives the output signal of the A/D converter, and generates a reception beam corresponding to each of a plurality of the directions. A beam scan controller 22 and a beam scan pattern table 52 are provided, and a changing pattern in the irradiation direction in a scan process due to the transmission beam is switched for each scan.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar apparatus, and more particularly, to a digital beam forming type radar apparatus.

[0002]

2. Description of the Related Art Conventionally, for example, see Japanese Patent Application Laid-Open No. 2-162285.
As disclosed in Japanese Unexamined Patent Application Publication No. H11-260, a digital beamforming type radar apparatus (hereinafter, simply referred to as "radar apparatus") is known. FIG. 24 shows a block diagram of a conventional radar device 10. As shown in FIG. The radar device 10 is a device that scans a monitoring area by electrically switching the irradiation direction of a transmission beam, and includes a timing controller 12.
The timing controller 12 is a circuit that generates timing for switching the irradiation direction of the transmission beam. The timing signal generated by the timing controller 12 is
Supplied to

The frequency controller 14 is a circuit for controlling the carrier frequency of the transmission beam, and switches the frequency of the transmission beam to a different value each time a timing signal is issued from the timing controller 12. A transmitter 16 is connected to the frequency controller 14. The transmitter 16 includes the frequency controller 1
4 to generate a transmission signal having a frequency corresponding to the output signal. The transmission signal generated by the transmitter 16 is transmitted to the power divider 1
8 is supplied.

[0006] A plurality of phase shifters 20 are connected to the power distributor 18. The power divider 18 evenly distributes the transmission signal supplied from the transmitter 16 to the plurality of phase shifters 20. All phase shifters 20 include a beam scan controller 22
Supplies a beam scanning control signal for determining the irradiation direction of the transmission beam. Each time the timing signal is issued from the timing controller 12, the beam scanning controller 22
The beam scanning control signal is changed to switch the irradiation direction of the transmission beam.

[0005] A circulator 26 is connected to the phase shifter 20 via a power amplifier 24. Radar device 10
In, the amount of phase delay corresponding to the beam scanning control signal is set in advance for each phase shifter 20. The phase shifter 20 supplies the transmission signal supplied from the power divider 18 to the power amplifier 24 with the phase delayed by the amount of phase delay required for each phase shifter 20. The power amplifier 24 appropriately amplifies the transmission signal beam supplied from the phase shifter 20 and supplies it to the circulator 26.

An element antenna 28 is connected to each of the circulators 26. Circulator 26
Can supply the transmission signal supplied from the power amplifier 24 to the element antenna 28. Element antenna 28
Radiates the transmission signal supplied as described above toward the monitoring area of the radar device 10. A composite wave of beams output from the plurality of element antennas 28 (hereinafter, “transmitted beam 3
“0”) proceeds in a direction corresponding to the phase difference between the transmission signals supplied to the element antennas 28, that is, in a direction corresponding to the beam scanning control signal generated by the beam scanning controller 22.

In the radar apparatus 10, the beam scanning control signal is switched so that the irradiation direction of the transmission beam 30 changes continuously in a predetermined direction every time the timing controller 12 issues a timing signal. Transmitter 1
As described above, the frequency of the transmission beam emitted by 6 is switched every time a timing signal is emitted. Therefore, according to the radar device 10, each time the timing signal is issued, the irradiation direction of the transmission beam 30 and the frequency thereof are switched.

[0008] The element antenna 28 receives the reception beam 32 incident from the monitoring area of the radar apparatus 10 and supplies the reception beam 32 to the circulator 26. The circulator 26 supplies the reception beam to the receiver 34. The receiver 34 includes:
A beam former 38 is connected via an A / D converter 36. When the reception beam 32 is incident on the radar device 10 from a predetermined direction θ, the individual element antennas 2
8 has a phase difference corresponding to the incident direction θ.

In other words, assuming that the reception beams received by the individual element antennas 28 include phase differences corresponding to the respective directions θ, and by generating and combining signals excluding those phase differences, Radar device 10 from a predetermined direction θ
Can be generated according to the reception beam 30 incident on the. In the radar device 10, the beamformer 38 simultaneously generates a plurality of signals respectively corresponding to the reception beams reaching the radar device 10 from a plurality of adjacent directions by using the above-described method.

A plurality of signals (received beams) generated by the beamformer 38 are supplied to a target detector 40. After transmitting the transmission beam in the predetermined direction θ, the target detector 40 detects the distance to the target existing in the θ direction based on the time until the reception beam from the direction θ is received. In addition, the target detector 40, based on the Doppler frequency superimposed on the reception beam from the θ direction,
The target speed existing in the θ direction is detected.

Next, the operation of the radar device 10 will be described with reference to FIGS. FIG. 25 shows the direction of the elevation angle θ2 and the elevation angle θ3 in the monitoring area of the radar device 50.
Shows a state where the target 42 exists near the boundary with the direction.
In FIG. 25, the distance between the target 42 and the radar device 10 is r _M. FIG. 26 is a timing chart for explaining the operation of the radar device 10 under the situation shown in FIG.

The radar apparatus 10 continuously outputs pulses of the transmission beam in the directions θ1 to θ3 (FIG. 26).
(A)). The transmission beam frequency is such that the irradiation direction is θ1 → θ
In synchronization with switching from 2 to θ3, f1 → f2 →
Switching is performed in the order of f3. Of the transmission beams irradiated as described above, the beam of the frequency f2 irradiated in the θ2 direction and the beam of the frequency f3 irradiated in the θ3 direction are reflected to the target 42. On the other hand, the beam of the frequency f1 irradiated in the θ1 direction passes through the space without being reflected by the target 42.

As a result, in the situation shown in FIG.
A receiving beam incident on the radar device 10 from a direction between θ2 and θ3, and a frequency of f3,
A reception beam incident on the radar device 10 from a direction between θ2 and θ3 is generated. These beams incident on the radar device 10 from the direction between θ2 and θ3 are recognized by the radar device 10 as a beam from the θ2 direction and also as a beam from the θ3 direction (FIG. 26). (C) and FIG. 26 (D)).

As described above, the radar apparatus 10 transmits a transmission beam having the frequency f2 in the θ2 direction, and transmits a transmission beam having the frequency f3 in the θ3 direction. Therefore, when a beam having the frequency f3 is incident from the θ2 direction, the radar device 10 can recognize that the beam is originally a beam corresponding to the direction θ3. Similarly, the radar device 10
When a beam of frequency f2 is incident from the θ3 direction,
It can be recognized that the beam is originally a beam corresponding to the θ2 direction.

[0015] More specifically, the radar device 10 is configured as shown in FIG.
6 (C) and FIG. 26 (D), only the beam of the frequency f2 incident from the θ2 direction and the beam of the frequency f3 incident from the θ3 direction are recognized as valid. And the direction θ
It can be recognized that there is a target that reflects the transmission beam near the boundary between 2 and the direction θ3.

After the transmission beam of frequency f2 has been transmitted,
The time t _M = 2r _M / c (where c is the speed of light) until the reception beam of frequency f2 is incident from the direction of θ2, and after the transmission beam of frequency f3 is transmitted, the reception beam of frequency f3 is Time t _M = 2 from the direction of θ3 to incidence
It is the same as r _M / c. Therefore, according to those reception beams, it can be recognized that the target exists at a position at the same distance from the radar apparatus 10 (a position at a distance r _M ) in both the direction θ2 and the direction θ3.

If the target exists near the boundary between the directions θ2 and θ3 and the target can be recognized at a position where the distance from the radar device 10 is equal in both the directions θ2 and θ3, the boundary between the two directions Can be recognized as having the same target 42. Therefore, according to the radar apparatus 10, when the transmission / reception beams shown in FIGS. 26A to 26D are obtained, it is possible to accurately detect that the situation shown in FIG. 25 occurs.

Assuming that the conventional radar device 10 emits a transmission beam having the same frequency in each direction, FIG.
As shown in FIG. 6 (C), the reception beam from the θ2 direction
(1) Reflected signal of transmission beam in θ2 direction (solid line pulse)
And (2) the reflected signal (dashed pulse) of the transmission beam in the θ3 direction, the cause of the two beams cannot be distinguished. In other words, FIG.
When the reception beam shown in (C) is obtained, (a) whether one target exists at the boundary between the θ2 direction and the θ3 direction, or (b) the position and the distance of the distance r _{M in} the direction of θ2 r _L = t _L ·
It cannot be determined whether there are two targets at the position of c / 2 (> r _M ) (where c is the speed of light).

Similarly, when the radar apparatus 10 irradiates a transmission beam having the same frequency in each direction, a reception beam (a beam including both a solid pulse and a dashed pulse) as shown in FIG. 26D is obtained. (A) θ2 direction and θ
Whether there is one target at the boundary with three directions, or
(b) Determining whether two targets exist at a position at a distance r _s = t _S · c / 2 (<r _M ) (where c is the speed of light) and a position at a distance r _M in the direction of θ3 Can not. in this way,
When the frequency of the transmission beam continuously irradiated in each direction by the radar apparatus 10 is the same, when the target is located at the boundary between two adjacent directions, the situation cannot be accurately detected. That is, the conventional radar device 10
By outputting the transmit beam while changing the frequency,
It enables highly accurate target detection.

[0020]

A conventional radar device 10
Is configured as described above, it is necessary to transmit a transmission beam and receive a reception beam at a plurality of frequencies in order to enable highly accurate target detection. For this reason, in the conventional radar device 10, a transmitter 16 capable of handling a plurality of frequencies and a frequency controller 14 for controlling the frequencies are required, and the phase shifter 2
0, the power amplifier 24 and the receiver 34 are required to have performance capable of coping with a predetermined frequency band.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a digital beamforming radar capable of detecting a target with high accuracy without using a plurality of frequencies. This is the first purpose.

[0022]

According to the first aspect of the present invention,
A radar apparatus, comprising: a phase shifter provided corresponding to each of the plurality of element antennas; and a transmission beam generation unit configured to transmit a transmission beam by electronically sequentially switching an irradiation direction to a plurality of directions; A / D converters provided corresponding to the respective element antennas, and a beamformer for receiving an output signal of the A / D converter, and generate a reception beam corresponding to each of a plurality of directions. It is characterized by comprising a receiving beam generating means and an irradiation pattern periodic switching means for periodically switching a switching pattern of the irradiation direction of the transmission beam.

According to a second aspect of the present invention, there is provided a radar apparatus comprising a phase shifter provided corresponding to each of a plurality of element antennas, and electronically changing an irradiation direction to a plurality of directions for transmission. A transmitting beam generating means for transmitting a beam, an A / D converter provided for each of the plurality of element antennas, and a beamformer for receiving an output signal of the A / D converter; Receiving beam generating means for generating a receiving beam corresponding to each of the directions,
A sweep pulse generating means for changing the frequency of the transmission beam in a predetermined sweep pattern; a sweep pattern switching means for switching the predetermined sweep pattern in synchronization with a switching timing of the irradiation direction of the transmission beam; and the sweep pulse generation means. Pulse compression means for changing the frequency of the receive beam with a compression pattern to cancel the sweep pattern used,
A filter for extracting a signal near a predetermined frequency from the reception beam whose frequency has been compressed by the pulse compression means.

According to a third aspect of the present invention, there is provided a radar apparatus comprising a phase shifter provided corresponding to each of a plurality of element antennas, and electronically switching an irradiation direction to a plurality of directions for transmission. A transmitting beam generating means for transmitting a beam, an A / D converter provided for each of the plurality of element antennas, and a beamformer for receiving an output signal of the A / D converter; Receiving beam generating means for generating a receiving beam corresponding to each of the directions,
When receive beams are obtained from two adjacent directions,
Beam scanning angle offset means for giving an offset of a predetermined angle smaller than the beam width in the irradiation direction of the transmission beam.

According to a fourth aspect of the present invention, there is provided a radar apparatus comprising a phase shifter provided for each of a plurality of element antennas, and electronically changing the irradiation direction to a plurality of directions for transmission. A transmitting beam generating means for transmitting a beam, an A / D converter provided for each of the plurality of element antennas, and a beamformer for receiving an output signal of the A / D converter; Receiving beam generating means for generating a receiving beam corresponding to each of the directions,
Modulation pulse generation means for code-modulating a transmission beam, code modulation pattern switching means for switching the code modulation pattern in synchronization with a switching timing of a transmission beam irradiation direction, and code modulation pattern used by the modulation pulse generation means Pulse compression means for demodulating a reception beam with a compression pattern for canceling, and a filter for extracting a reference modulation signal from the reception beam after being demodulated by the pulse compression means, characterized by comprising: is there.

According to a fifth aspect of the present invention, there is provided a radar apparatus comprising a phase shifter provided in correspondence with each of a plurality of element antennas, and transmitting an electronic beam by sequentially switching an irradiation direction to a plurality of directions. A transmitting beam generating means for transmitting a beam, an A / D converter provided for each of the plurality of element antennas, and a beamformer for receiving an output signal of the A / D converter; Receiving beam generating means for generating a receiving beam corresponding to each of the directions,
Doppler frequency detection means for detecting a Doppler frequency superimposed on a reception beam corresponding to each of the plurality of directions, and, when reception beams are received from two adjacent directions, being superimposed on the reception beams. Target determination means for determining whether or not the cause of the reception beams is the same target based on the Doppler frequency being
It is characterized by having.

According to a sixth aspect of the present invention, there is provided a radar apparatus comprising a phase shifter provided corresponding to each of a plurality of element antennas, and electronically changing the irradiation direction to a plurality of directions for transmission. A transmitting beam generating means for transmitting a beam, an A / D converter provided for each of the plurality of element antennas, and a beamformer for receiving an output signal of the A / D converter; Receiving beam generating means for generating a receiving beam corresponding to each of the directions,
An irradiation direction switching means for switching the irradiation direction of the transmission beam in a pattern in which the transmission beam is not continuously irradiated in the adjacent direction.

According to a seventh aspect of the present invention, there is provided a radar apparatus comprising a phase shifter provided corresponding to each of a plurality of element antennas, and electronically changing an irradiation direction to a plurality of directions for transmission. A transmitting beam generating means for transmitting a beam, an A / D converter provided for each of the plurality of element antennas, and a beamformer for receiving an output signal of the A / D converter; Receiving beam generating means for generating a receiving beam corresponding to each of the directions,
After receiving beams from two adjacent directions,
An irradiation pattern switching means for changing a switching pattern of the irradiation direction of the transmission beam so that the transmission beam is not continuously irradiated in the two directions.

The invention according to claim 8 is the radar device according to any one of claims 1 to 7, wherein when reception beams are obtained from a plurality of adjacent directions, the intensity ratio of the reception beams is obtained. Is provided with an angle measurement processor for performing angle measurement processing for obtaining details of the target existence angle based on.

According to a ninth aspect of the present invention, in the radar apparatus according to the eighth aspect, when receiving beams are received from three or more adjacent directions, optimal receiving to be subjected to angle measurement processing is performed. It is characterized by comprising a beam selecting means for selecting a beam.

[0031]

Embodiments of the present invention will be described below with reference to the drawings. Elements common to the drawings are denoted by the same reference numerals, and redundant description will be omitted.

Embodiment 1 FIG. 1 shows a digital beamforming radar device 5 according to a first embodiment of the present invention.
FIG. The radar device 50 is a device that continuously generates a series of transmission beams at predetermined time intervals and monitors a monitoring area. In the radar device 50, a series of transmission beams that scan the monitoring area are generated by continuously outputting pulsed transmission beams while electrically switching the irradiation direction.

The radar device 50 has a timing controller 12. The timing controller 12 starts the scanning by the transmission beam (scanning start timing),
And a circuit for generating a timing for switching the irradiation direction of the transmission beam (direction switching timing). The signal generated by the timing controller 12 is supplied to a transmitter 16. The transmitter 16 receives a timing signal emitted from the timing controller 12 and generates a transmission signal of the frequency fc. The transmission signal generated by the transmitter 16 is supplied to the power distributor 18.

A plurality of phase shifters 20 are connected to the power distributor 18. The power divider 18 evenly distributes the transmission signal supplied from the transmitter 16 to the plurality of phase shifters 20. All phase shifters 20 include a beam scan controller 22
Supplies a beam scanning control signal. The beam scanning control signal is a signal for determining the irradiation direction of the transmission beam, and more specifically, is a signal for instructing each phase shifter 20 of the magnitude of the phase delay to be generated. .

In this embodiment, the individual phase shifters 20
For each of them, the relationship between the beam scanning control signal and the amount of phase delay is predetermined. Upon receiving the beam scanning control signal and the transmission signal as described above, the phase shifter 20 generates a transmission signal whose phase is delayed with respect to the received transmission signal by a phase delay amount corresponding to the beam scanning control signal. Output. Therefore, each phase shifter 20 appropriately changes the phase delay amount of the transmission signal every time the direction switching timing is issued.

The transmission signal output from phase shifter 20 is supplied to element antenna 28 via power amplifier 26 and circulator 26. The transmission signal that has reached the element antenna 28 is thereafter output toward the monitoring area of the radar device 50. The composite wave of the beams output from the plurality of element antennas 28 (that is, the transmission beam 30) travels in a direction corresponding to the phase difference between the transmission signals supplied to the element antennas 28. Therefore, according to the radar device 50, the irradiation direction of the transmission beam 30 is switched every time the direction switching timing is issued from the timing controller 12.

The element antenna 28 receives the reception beam 32 incident from the monitoring area of the radar device 50 and supplies a reception signal to the circulator 26. Circulator 2
6 supplies the received signal to the receiver 34. Receiver 3
4 has a beamformer 38 via an A / D converter 36.
Is connected. When the reception beam 32 is incident on the radar device 50 from a predetermined direction θ, the reception beams received by the individual element antennas 28 have a phase difference corresponding to the incident direction θ.

In other words, assuming that the reception beams received by the individual element antennas 28 include the phase differences corresponding to the directions θ, and generate and combine signals excluding those phase differences, Radar device 50 from a predetermined direction θ
At the same time, a signal corresponding to the receiving beam 30 that is incident on the device can be generated. The beamformer 38 recognizes the monitoring area of the radar device 50 as a plurality of spatially divided areas, and uses the above-described technique to generate a signal corresponding to a reception beam incident from the direction of each area. Are generated at the same time.

The plurality of signals generated by the beamformer 38 are supplied to a target detector 40. The target detector 40 is configured to transmit a transmission beam in a predetermined direction θ, and then to a target existing in the θ direction based on a time until a reception signal resulting from the reception beam from the direction θ is received. Detect distance. Hereinafter, for convenience, the signal received by the beamformer 38 is also referred to as a “reception beam”, and the signal supplied to the transmission antenna 28 is also referred to as a “transmission beam”. The target detector 40 detects the speed of a target existing in the θ direction based on the Doppler frequency superimposed on the reception beam from the θ direction.

The radar apparatus 50 according to the present embodiment is characterized in that it has a beam scanning pattern table 52. A timing signal (scanning start timing and direction switching timing) is supplied from the timing controller 12 to the beam scanning pattern table 52. The beam scanning pattern table 52 performs (1) switching of the irradiation direction switching pattern every time the scanning start timing is issued, and (2) every time the direction switching timing is issued,
The switching of the irradiation direction is instructed to the beam scanning controller 22 according to the irradiation direction switching pattern in use.

FIG. 2 shows a beam scanning pattern table 52.
5 is a table showing the contents of an instruction. In the following description, for simplicity, it is assumed that the radar apparatus 50 sets three spatially adjacent directions, that is, the θ1, the θ2, and the θ3 directions as the monitoring areas.

As shown in FIG. 2, according to the beam scanning pattern table 52, during the first scan (first scan), the irradiation direction of the transmission beam 30 is changed from θ1 → θ2 → θ.
A switching pattern that changes in the order of 3 is used. In this case, in the spatially adjacent θ1 and θ2 directions,
The transmission beam 30 is continuously irradiated in the θ2 direction and the θ3 direction.

According to the beam scanning pattern table 52, at the time of the second scanning (second scanning), a switching pattern in which the irradiation direction of the transmission beam 30 changes in the order of θ2 → θ1 → θ3 is used. In this case, the transmission beam 30
Is one spatially adjacent combination (θ2 direction and θ
One direction) is continuously irradiated, while the other spatially adjacent combination (θ2 direction and θ3 direction) is discontinuously irradiated.

According to the beam scanning pattern table 52, the switching pattern of the irradiation direction is changed each time the scanning by the transmission beam 30 is repeated. For this reason, according to the radar device 50 of the present embodiment, it is possible to avoid a situation in which the transmission beam 30 is continuously irradiated in two adjacent directions continuously. Less than,
FIGS. 3 to 5 and 25 together with FIGS. 1 and 2
The operation of the radar device 50 of the present embodiment will be described in more detail with reference to FIG.

FIG. 3 is a timing chart for explaining the operation of the radar device 50 when a single target 42 exists near the boundary between the θ2 direction and the θ3 direction as shown in FIG. The radar device 50 of the present embodiment includes:
In the first scan, the transmitting beam is continuously output in the order of θ1 → θ2 → θ3. In this case, a transmission waveform composed of three continuous beams 54, 56 and 58 is obtained as shown in FIG.

Of the transmission beam 30 output from the radar device 50, the beam 54 irradiated in the θ1 direction passes through the space without being reflected by the target. On the other hand, the beam 56 radiated in the θ2 direction and the beam 58 radiated in the θ3 direction are reflected by the target 42, respectively, and then received by the reception beam heading from the vicinity of the boundary between the θ2 direction and the θ3 direction toward the radar device 50. Become. The beam incident from such a direction is recognized by the radar device 50 as a beam from the θ2 direction and also as a beam from the θ3 direction. For this reason, the radar device 50 recognizes a beam composed of two continuous beams 60 and 62 as a received beam from the θ2 direction, and a beam including two continuous beams 64 and 66 as a received beam from the θ3 direction. (FIG. 3 (C) and FIG.
(D)).

The situation in which the timing chart shown in FIG. 3 can be obtained is not limited to the case where the target exists near the boundary between the θ2 direction and the θ3 direction as shown in FIG.
FIG. 4 shows another situation in which the timing chart shown in FIG. 3 can be obtained. FIG. 4 specifically shows the distance r _{M in the} θ2 direction.
This shows a situation in which targets 68 and 70 exist at the position of distance r and distance r _L respectively, and targets 72 and 74 exist at the position of distance r _S and distance r _{M in} the θ3 direction, respectively.

In the situation shown in FIG. 4, when the transmission beam 30 having the waveform shown in FIG. 3A is irradiated, the transmission beam in the θ2 direction is reflected by the targets 68 and 70, respectively. Receive beams 60 and 62 shown in FIG. 3 (C) are generated. Similarly, the transmission beam in the θ3 direction is reflected by the targets 72 and 74, so that
The reception beams 64 and 66 shown in FIG. 3D are generated. Therefore, in the radar device 50 of the present embodiment,
When the reception beam 30 having the waveforms shown in FIGS. 3B to 3D is obtained, the target state cannot be determined based only on the reception beam 30.

FIG. 5 is a timing chart for explaining the operation of the radar apparatus 50 in the second scan under the situation shown in FIG. 25 or FIG. Specifically, FIG.
5A shows the waveform of the transmission beam in the second scan, and FIG.
(B) to FIG. 5 (D) show the waveform of the reception beam obtained under the situation shown in FIG. 25, and FIGS. 5 (E) to 5 (G) show the reception beam obtained under the situation shown in FIG. 3 shows the waveforms of FIG.

As described above, the radar device 50 of the present embodiment continuously outputs transmission beams in the order of θ2 → θ1 → θ3 in the second scan. As a result, as shown in FIG. 5A, a beam 56 corresponding to θ2, a beam 54 corresponding to θ1, and a beam 58 corresponding to θ3 are continuously output. A single target 4 at the boundary between the θ2 direction and the θ3 direction
When 2 exists (in the case of FIG. 25), the reflected wave of the beam 56 irradiated in the θ2 direction is simultaneously received as the reception beam 60 from the θ2 direction and the reception beam 64 from the θ3 direction. And their beams 60 and 64
Is received, at predetermined intervals, the reflected waves of the beam 58 irradiated in the θ3 direction are simultaneously received as the reception beam 62 from the θ2 direction and the reception beam 66 from the θ3 direction (FIG. 5 ( C) and FIG. 5 (D)).

On the other hand, when there are a plurality of targets in each of the θ2 direction and the θ3 direction (in the case of FIG. 4),
Received beams 60 and 62 generated by reflecting beams 56 irradiated in two directions on targets 68 and 70 continuously enter radar device 50 from the θ2 direction. The beam 58 irradiated in the θ3 direction is substantially synchronized with the time when the beam 62 arrives at the radar device 50.
Beam 64 generated by reflection at and 74
And 66 continuously start to enter the radar apparatus 50 from the θ3 direction (FIGS. 5F and 5G).

As described above, according to the radar device 50, 2
By performing the scanning operation, the situation shown in FIG. 4 and the situation shown in FIG. 25 can be distinguished. That is, according to the radar device 50 of the present embodiment, the adjacent two
By avoiding the situation where the transmit beam is continuously irradiated in one direction, the situation where the target exists at the boundary of the adjacent direction and the situation where different targets exist in those directions are considered. It can be determined accurately. Therefore, according to the radar device 50 of the present embodiment, highly accurate target detection can be performed without changing the frequency of the transmission beam.

In the above embodiment, the timing controller 12, the transmitter 16, the power distributor 18, the phase shifter 2
0, the power amplifier 24, the circulator 26, and the element antenna 28 are the "transmission beam generating means" according to claim 1, and the element antenna 28, the circulator 26, the receiver 34, the A / D converter 36, and the beam former 38 are the same. The “receiving beam generating means” according to claim 1, further comprising: a beam scanning pattern table (52) and a beam scanning controller (22).
2. The "irradiation pattern periodic switching means" according to claim 1.
, Respectively.

Embodiment 2 Next, a second embodiment of the present invention will be described with reference to FIGS. FIG.
Shows a block diagram of the radar device 80 of the present embodiment. The radar device 80 is a frequency sweep type pulse compression radar, and includes a pulse compression pattern table 82. The timing signal is supplied from the timing controller 12 to the pulse compression pattern table 82. The pulse compression pattern table 82 stores a plurality of pulse sweep patterns for generating a sweep pulse for appropriately changing the carrier frequency fc as a center frequency.

FIGS. 7 to 9 show three pulse sweep patterns P1 to P3 stored in the pulse compression pattern table 82, respectively. Pattern P1 shown in FIG.
Is a pattern in which the frequency of the sweep pulse changes linearly from fc−Δf1 to fc + Δf1 during a time corresponding to the pulse width PW. The pattern P2 shown in FIG. 8 is a pattern in which the frequency of the sweep pulse changes linearly from fc + Δf2 to fc−Δf2 during a time corresponding to the pulse width PW. Further, a pattern P3 shown in FIG. 9 is a pattern in which the frequency of the sweep pulse changes linearly from fc−Δf3 to fc + Δf3 during a time corresponding to the pulse width PW. In the present embodiment, the pulse compression pattern table 82 stores P
The pulse sweep pattern to be used is changed in the order of 1 → P2 → P3.

A sweep pulse generator 84 is connected to the pulse compression pattern table 82. The sweep pulse generator 84 generates a sweep pulse having the carrier frequency fc as a reference frequency in accordance with the pulse sweep pattern supplied from the pulse compression pattern table 82. FIG. 10 shows a continuous waveform of three sweep pulses generated by the sweep pulse generator 84. As shown in FIG. 10, the sweep pulse generator 84 includes a pulse swept according to the pattern P1, a pulse swept according to the pattern P2, and a pattern P3.
Are continuously generated, and the three sweep pulses are sequentially output at each irradiation direction switching timing.

The sweep pulse output from the sweep pulse generator 84 passes through the transmitter 16 and the like, and then passes through the element antenna 2.
From 8, the light is emitted to the monitoring area of the radar device 80. For this reason, in the radar device 80 of the present embodiment, the receiving antenna 32 that changes the frequency in the sweep pattern corresponding to any of the patterns P1 to P3 is received by the element antenna 28. In the radar device 80, the reception beam 32
Are the same as in the first embodiment, the receiver 34, the A / D
It is processed by the converter 36 and the beamformer 38. As a result, a reception beam in each direction θ1, θ2, or θ3 is generated.

The received beam generated by the beam former 38 is supplied to a pulse compressor 86. Pulse compressor 8
Reference numeral 6 denotes a target detector 4 which compresses the received beam based on the sweep pattern (P1 to P3) stored in the pulse compression pattern table 82, performs appropriate filtering, and
Output to 0.

More specifically, the pulse compressor 86 performs a pulse compression process for canceling the sweep pattern P1 on the reception beam in the θ1 direction. According to the above processing, of the reception beams incident from the θ1 direction, the reception beam on which the sweep pattern P1 is reflected, that is, θ
The reception beam resulting from the transmission beam in one direction becomes a signal near the carrier frequency fc.

On the other hand, a reception beam on which the sweep pattern P1 is not reflected, that is, a reception beam incident from another direction adjacent to the θ1 direction becomes a signal having a frequency greatly deviating from the carrier frequency fc. The pulse compressor 86 performs filtering for extracting only a signal near the carrier frequency fc from these signals, and supplies only the resulting signal to the target detector 40 as a reception beam from the θ1 direction. As a result, the target detector 40 has θ1
Only the reception beam resulting from the transmission beam irradiated in the direction is received as the reception beam in the θ1 direction.

The pulse compressor 86 performs the same processing as that for the reception beam in the θ1 direction for the reception beam in the θ2 direction and the reception beam in the θ3 direction. Therefore, the target detector 40 can obtain an accurate reception beam from which reception beams entering from adjacent directions have been removed in all directions.

FIG. 11 is a timing chart for explaining the operation of the radar device 80 under the situation shown in FIG. As shown in FIG. 11A, according to the radar device 80, the transmission beam swept by the pattern P1, the transmission beam swept by the pattern P2, and the pattern P3
Are transmitted in directions θ1 and θ2, respectively.
It is continuously transmitted in the directions of 2 and θ3. As a result, the radar device 80 includes the signals shown in FIGS.
The reception beam shown in (D) is received. That is, the radar apparatus 80 receives a reception beam including the beam reflected by the pattern P2 and the beam reflected by the pattern P3,
It is received as a receive beam in the θ2 direction and as a receive beam in the θ3 direction.

The pulse indicated by the broken line in FIG. 11C (the beam reflected by P3) and the pulse indicated by the broken line in FIG. 11D (the beam reflected by P2)
Are excluded from the receive beam by the pulse compressor 86. Therefore, according to the radar device 80 of the present embodiment, even if the frequency of the transmission beam is not largely changed, an accurate target can be obtained similarly to the conventional radar device (see FIG. 24) that greatly changes the frequency. Detection can be performed.

By the way, in the above embodiment, a pattern in which the frequency of the sweep pulse is changed linearly is used as the pulse sweep pattern, but the pulse sweep pattern is not limited to this. Alternatively, a pattern that changes the frequency of the pulse nonlinearly may be used.

In the above embodiment, the timing controller 12, the transmitter 16, the power distributor 18, the phase shifter 2
0, the power amplifier 24, the circulator 26, and the element antenna 28 are the "transmission beam generating means" according to the second embodiment, and the element antenna 28, the circulator 26, the receiver 34, the A / D converter 36, and the beam former 38 are the same. The "reception beam generating means" according to claim 2, the sweep pulse generator 84 is "sweep pulse generating means" according to claim 2, and the pulse compression pattern table 82 is "sweep pattern switching means" according to claim 2. The pulse compressor 86 corresponds to the "pulse compression means" and the "filter" in the second aspect, respectively.

Embodiment 3 Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 12 shows a block diagram of a radar device 90 according to Embodiment 3 of the present invention. The radar device 90 of the present embodiment includes a beam scanning angle offset controller 92. A signal representing the state of the target is supplied from the target detector 40 to the beam scanning angle offset controller 92. Target detector 40
Determines that there is a possibility that a target exists near the boundary between two adjacent directions when similar reception beams are received at the same timing from two adjacent directions.

When the target detector 40 makes the above determination, the beam scanning angle offset controller 92 outputs a signal for offsetting the irradiation direction of the transmission beam to any direction by a predetermined angle. To the vessel 22. In the present embodiment, the offset angle is
The predetermined angle smaller than the transmission beam width, more specifically,
The angle θb / 2 is set to half the transmission beam width. Therefore, according to the radar device 90, the normal mode in which the transmission beam is continuously radiated in the directions of θ1, θ2, and θ3, and the transmission beam has the θ1-θb / 2, θ2-
θb / 2 and θ3-θb / 2 (or θ1 +
The offset mode in which irradiation is continuously performed in the directions θb / 2, θ2 + θb / 2, and θ3 + θb / 2) can be selectively realized.

FIG. 13 is a timing chart for explaining the operation when the normal mode operation is performed under the situation shown in FIG. As shown in FIG. 13A, the radar device 90 has θ1, θ2 and θ3 in the normal mode.
The transmission beam is continuously irradiated in the direction of. In this case, if the target 42 exists near the boundary between θ2 and θ3,
As shown in FIGS. 13B to 13D, a reception beam including two continuous pulse waveforms is received from both the θ2 direction and the θ3 direction. Even on the basis of only such a reception beam, the target state cannot be accurately detected as in the case of the first embodiment.

When the reception beam shown in FIG. 13 is received, the radar device 90 of this embodiment offsets the transmission direction of the transmission beam by a predetermined angle θb / 2. FIG.
Indicates a relationship between the transmission beam 30 and the reception beam 32 generated after the above-described offset is performed and the position of the target 42. When the above-described offset is performed, the area near the boundary between the θ2 direction and the θ3 direction becomes an area located substantially at the center in the direction of θ2−θb / 2.

FIG. 15 is a diagram for explaining the operation of the radar device 90 after the situation shown in FIG. 25 changes to the situation shown in FIG. 14 by starting the offset mode. As shown in FIG. 15A, in the offset mode, in the offset mode, θ1−θb / 2, θ2−θb / 2
And a transmission beam is continuously irradiated in the directions of θ3 and θb / 2. In this case, the irradiated beam is θ2-
The light is reflected by the target 42 only in the θb / 2 direction. As a result, as shown in FIGS. 15B to 15D, a reception beam including only a single pulse is incident on the radar device from the θ2-θb / 2 direction.

The radar device 90 is shown in FIGS.
When the reception beam shown in (D) is obtained, θ2−θb
It can be accurately recognized that a single target 42 exists in the / 2 direction. Therefore, the radar device 9 of the present embodiment
According to 0, the target in the monitoring area can be detected with high accuracy without changing the frequency of the transmission beam.

In the above embodiment, in the offset mode, the irradiation direction of the transmission beam is always offset by θb / 2 degrees. However, the present invention is not limited to this. May be set to different widths within a range smaller than the beam width of the transmission beam. Furthermore, if the position of the target 42 existing near the boundary in the adjacent direction can be detected in detail by the angle measurement processing described later, the target 42
The offset width may be determined so that the position is near the center of the transmission beam.

In the above embodiment, the timing controller 12, the transmitter 16, the power distributor 18, the phase shifter 2
0, the power amplifier 24, the circulator 26, and the element antenna 28 are the “transmission beam generating means” according to the third embodiment, and the element antenna 28, the circulator 26, the receiver 34, the A / D converter 36, and the beam former 38 are the same. The beam scanning angle offset controller 92 corresponds to the “receiving beam generating means” of the third aspect, and corresponds to the “beam scanning angle offset means” of the third aspect.

Embodiment 4 Next, FIG. 16 and FIG.
Embodiment 4 of the present invention will be described with reference to FIG.
FIG. 16 is a block diagram of the radar apparatus 100 according to the present embodiment. The radar device 100 is a code modulation pulse compression radar, and includes a code modulation pattern table 102. A timing signal (irradiation direction switching timing and scanning start timing) is supplied from the timing controller 12 to the code modulation pattern table 102.
The code modulation pattern table 102 stores a plurality of modulation patterns for generating code modulation pulses. The code modulation pattern table 102 changes the modulation pattern to be used every time the irradiation direction switching timing is issued.

A modulation pulse generator 104 is connected to the code modulation pattern table 102. The modulation pulse generator 104 generates a modulation pulse modulated in a predetermined pattern according to the modulation pattern supplied from the code modulation pattern table 102. FIG. 17 shows a continuous waveform of three modulation pulses generated by the modulation pulse generator 104. As shown in FIG. 17, the modulation pulse generator 104 uses the modulation pattern 1 when the irradiation direction is θ1, the modulation pattern 2 when the irradiation direction is θ2, and uses the modulation pattern 2 when the irradiation direction is θ3. In some cases, modulation pulses are generated using the modulation pattern 3.

In the present embodiment, the modulation pulse is composed of a combination of a “0” signal having an amplitude at a reference phase and a “π” signal having a deviation of π from the phase.
This is a bit signal. The modulation patterns 1 to 3 are a pattern in which the third bit is “π”, a pattern in which the fifth bit is “π”, and a pattern in which the second, third, and fifth bits are “π”.

The sweep pulse output from the modulation pulse generator 104 passes through the transmitter 16 and the like, and then is emitted from the element antenna 28 to the monitoring area of the radar device 100. For this reason, in the radar apparatus 100 of the present embodiment, the receiving beam 32 having a pattern corresponding to any one of the modulation patterns 1 to 3 is received by the element antenna 28.
In the radar device 100, the reception beam 32 includes a receiver 34 and an A / D converter 36, as in the first embodiment.
And a beamformer 38. As a result, a reception beam in each direction θ1, θ2, or θ3 is generated.

The reception beam generated by the beam former 38 is supplied to a pulse compressor 106. The pulse compressor 106 compresses the received beam based on the modulation patterns 1 to 3 stored in the code modulation pattern table 102, performs appropriate filtering, and outputs the result to the target detector 40.

More specifically, the pulse compressor 106
A pulse compression process for canceling the modulation pattern 1 is performed on the reception beam in the direction. According to the above processing, of the reception beams incident from the θ1 direction, the reception beam on which the modulation pattern 1 is reflected, that is, the reception beam
Receive beams resulting from transmit beams in the direction are properly demodulated.

On the other hand, a reception beam on which the modulation pattern 1 is not reflected, that is, a reception beam incident from another direction adjacent to the θ1 direction, becomes an abnormal signal without being appropriately demodulated. The pulse compressor 106 performs filtering for extracting only a properly demodulated signal from those signals, and converts only the resulting signal into θ
The beam is supplied to the target detector 40 as a reception beam from one direction. As a result, the target detector 40 displays only the reception beam resulting from the transmission beam irradiated in the θ1 direction as θ
It is received as a one-way receive beam.

The pulse compressor 106 also detects the reception beam in the θ2 direction and the reception beam in the θ3 direction by θ1
The same processing as that for the reception beam in the direction is performed. Therefore, the target detector 40 can obtain an accurate reception beam from which reception beams entering from adjacent directions have been removed in all directions. For this reason, according to the radar device 100 of the present embodiment, the conventional radar device (see FIG. 24) that largely changes the frequency of the transmission beam even though the frequency of the transmission beam is not changed, or the above-described embodiment. Similar to the radar device 80 according to the second aspect, accurate target detection can be performed.

By the way, in the above-described embodiment, for the sake of explanation, it is assumed that a modulation pulse is generated using 5-bit code modulation. However, the present invention is not limited to this. The modulation code may be generated by a method using a code, an M sequence, or the like.

In the above embodiment, the timing controller 12, the transmitter 16, the power distributor 18, the phase shifter 2
0, the power amplifier 24, the circulator 26, and the element antenna 28 are the "transmitting beam generating means" according to the fourth embodiment, and the element antenna 28, the circulator 26, the receiver 34, the A / D converter 36, and the beam former 38 are the same. The "modulation pulse generator" of the fourth aspect is the "modulation pulse generator", and the code modulation pattern table 102 is the "code modulation pattern switching" of the fourth aspect. The pulse compressor 106 corresponds to the “means”, and corresponds to the “pulse compression means” and the “filter” in the fourth aspect, respectively.

Embodiment 5 Next, referring to FIG.
Embodiment 5 of the present invention will be described. FIG. 18 shows a block diagram of a radar apparatus 110 according to Embodiment 5 of the present invention. The radar device 110 includes the coherent integrator 1
12 are provided. The radar device 110 is the first embodiment.
As in the case of the apparatus described above, the monitoring area is repeatedly scanned every predetermined time. The beam former 38 simultaneously generates a reception beam corresponding to each direction each time an individual scan is performed. The coherent integrator 112 coherently integrates the reception beam in each direction over a predetermined period.

The result of the coherent integration reflects the phase information of the received beam obtained corresponding to each scan. The above coherent integration result is supplied to the target detector 40 and to the Doppler frequency determiner 114. The target detector 40 performs target detection for each direction based on the coherent integration result. On the other hand, the Doppler frequency determination unit 114 determines the target Doppler frequency detected for each direction by processing the result of the coherent integration with the Doppler filter.

The detection result of the target detector 40 and the determination result of the Doppler frequency determination unit 114 are
6. The target determiner 116 determines whether the targets detected in each of the two adjacent directions indicate the same Doppler frequency based on the results. If the targets are the same, the two Doppler frequencies should be equal because the relative speed with the radar device 110 is the same. On the other hand, if the targets are different, the two Doppler frequencies should have different values. From the above viewpoint, the target determiner 1
16 judges that the targets detected in the two adjacent directions are the same target when both of them show the same Doppler frequency. On the other hand, if the two targets have different Doppler frequencies, it is determined that different targets exist in two adjacent directions.

According to the above processing, it is possible to accurately discriminate between the case where a single target exists near the boundary between two adjacent directions and the case where different targets exist in the two directions. it can. Therefore, according to the radar apparatus 110 of the present embodiment, highly accurate target detection can be performed without changing the frequency of the transmission beam.

In the above embodiment, the timing controller 12, the transmitter 16, the power distributor 18, the phase shifter 2
0, the power amplifier 24, the circulator 26, and the element antenna 28 are the "transmission beam generating means" according to claim 5, and the element antenna 28, the circulator 26, the receiver 34, the A / D converter 36, and the beam former 38 are the same. The Doppler frequency determination unit 114 may be included in the “reception beam generation unit” according to claim 5, and the target determination unit 116 may be included in the “Doppler frequency detection unit” according to claim 5.
These correspond to “target determination means” described above.

Embodiment 6 FIG. Next, FIG. 24 and FIG.
Embodiment 6 of the present invention will be described with reference to FIG.
The radar apparatus according to Embodiment 6 of the present invention has the same system configuration as the conventional radar apparatus 10 shown in FIG. The radar device according to the present embodiment is realized by using a predetermined pattern described later as the irradiation direction switching pattern of the transmission beam when scanning the monitoring area with the transmission beam.

FIG. 19 is a view for explaining an irradiation direction switching pattern used in the radar apparatus of the present embodiment. As shown in FIG. 19, the radar apparatus of the present embodiment irradiates a transmission beam in five directions from θ1 to θ5. Further, the radar apparatus according to the present embodiment has a pattern in which a transmission beam is not continuously irradiated in two adjacent directions in the five directions, for example, θ1 → θ
The transmission beam is irradiated in the order of 3 → θ5 → θ2 → θ4.

According to the above-described irradiation direction switching pattern, the target 42 is located near the boundary between two adjacent directions, for example, θ2
Even if it exists near the boundary between the direction and the θ3 direction, θ2
Neither the reception beam from the direction nor the reception beam from the θ3 direction becomes a continuous reception signal. Therefore, according to the radar device 60 of the present embodiment, similarly to the case of the first embodiment, highly accurate target detection can be performed without changing the frequency of the transmission beam.

In the above embodiment, the timing controller 12, the transmitter 16, the power distributor 18, the phase shifter 2
0, the power amplifier 24, the circulator 26, and the element antenna 28 are the "transmission beam generating means" according to the above-described claim 6, and the element antenna 28, the circulator 26, the receiver 34, the A / D converter 36, and the beam former 38 are the same. The beam scanning controller 22 corresponds to the “reception beam generating means” according to claim 6, and the beam scanning controller 22 changes the irradiation direction of the transmission beam in a pattern in which the transmission beam is not continuously irradiated in the adjacent direction. By performing the switching, the “irradiation direction switching means” according to claim 6 is realized.

Embodiment 7 FIG. Next, referring to FIG.
Embodiment 7 of the present invention will be described. FIG. 20 shows a block diagram of a radar apparatus 120 according to Embodiment 7 of the present invention. The radar device 90 of the present embodiment includes a beam scanning pattern table 122 and a table switch 124. The table detector 124 includes the target detector 4
From 0, a signal representing the target state is supplied. When a similar reception beam is received at the same timing from two adjacent directions, the target detector 40 determines that there is a possibility that a target exists near the boundary between the two directions.

The table switch 124 is provided for the target detector 40.
When the above determination is made, the irradiation direction switching pattern of the transmission beam is switched to a pattern in which the transmission beam is not continuously irradiated in the two adjacent directions. For example, as shown in FIG.
Is present near the boundary between the θ2 direction and the θ3 direction, θ
By using a pattern for switching the irradiation direction in the order of 1 → θ2 → θ3, it is recognized that the target 42 may be present near the boundary between the θ2 direction and the θ3 direction. in this case,
At the time of the next scan, in order to avoid continuous transmission beam irradiation in the θ2 direction and the θ3 direction, θ2 → θ1 →
A pattern for switching the irradiation direction in the order of θ3 is used.

According to the pattern in which the irradiation direction is switched in the order of θ2 → θ1 → θ3, as in the first embodiment, is there a single target near the boundary between two adjacent directions? Alternatively, it can be determined whether the target exists in each of the two directions. For this reason, according to the radar apparatus 120 of the present embodiment, accurate target detection can be performed without changing the frequency of the transmission beam.

In the above embodiment, the timing controller 12, the transmitter 16, the power distributor 18, the phase shifter 2
0, the power amplifier 24, the circulator 26, and the element antenna 28 are the "transmission beam generating means" according to the above-mentioned claim 7, and the element antenna 28, the circulator 26, the receiver 34, the A / D converter 36, and the beam former 38 are the same. 8. A beam scanning pattern table 122 and a table switching unit 12 according to claim 7, wherein
4 is the "irradiation pattern switching means" according to claim 7,
Each is equivalent.

Embodiment 8 FIG. Next, FIG. 21 and FIG.
Embodiment 8 of the present invention will be described with reference to FIG.
FIG. 21 shows a block diagram of a radar apparatus 130 according to Embodiment 8 of the present invention. The radar device 130 of the present embodiment
Has an angle measurement processor 132 in addition to the system configuration of the radar device 50 (see FIG. 1) of the first embodiment. The angle measurement processor 132 is a circuit for specifying in detail the position of the target recognized by the target detector 40 as existing near the boundary between two adjacent directions using a known amplitude comparison angle measurement method.

[0098] The radar apparatus 130 of the present embodiment executes the target detection process by switching the irradiation direction switching pattern for each scan, similarly to the radar apparatus 50 of the first embodiment. FIG. 22A shows the waveform of the transmission beam emitted from the radar device 130 at the first scan and the second scan. FIGS. 22B to 22D show the case where the target 42 exists near the boundary between the θ2 direction and the θ3 direction, more specifically, at a position slightly offset from the boundary in the θ2 direction. 4 shows a waveform of a reception beam obtained.

As in the first embodiment, when the target 42 exists near the boundary between the θ2 direction and the θ3 direction,
A reception beam including two consecutive pulses is obtained in both the θ2 direction and the θ3 direction corresponding to the transmission beam of the first scan. In this case, a reception beam including two discontinuous pulses in both the θ2 direction and the θ3 direction is obtained corresponding to the transmission beam in the second scan. The target detector 40 can recognize that the target 42 exists near the boundary between the θ2 direction and the θ3 direction based on these received beams.

By the way, the amplitude (intensity) of the reception beam caused by the transmission beam irradiated in the θ2 direction increases as the target 42 is located near the center in the θ2 direction. Similarly, the amplitude (intensity) of the reception beam caused by the transmission beam irradiated in the θ3 direction increases as the target 42 is located near the center in the θ3 direction. Therefore, the amplitudes of the two reception beams obtained when the target 42 exists near the boundary between the θ2 direction and the θ3 direction, that is, the amplitude of the reception beam due to the transmission beam in the θ2 direction and the amplitude of the transmission beam in the θ3 direction. A difference occurs in the amplitude of the reception beam according to the position of the target 42.

FIGS. 22 (C) and 22 (D) show that the amplitude of the receiving beam caused by the transmitting beam in the θ2 direction is smaller than that of the transmitting beam in the θ3 direction because the target 42 is located in the direction θ2. In this case, the amplitude of the received beam exceeds the amplitude of the received beam. In the present embodiment, when the target detector 40 recognizes that the target 42 exists near the boundary between the direction θ2 and the direction θ3, the reception beam including the information on the magnitude of the amplitude is supplied to the angle measurement processor 132. Is done.

The angle measurement processor 132 calculates a ratio between the amplitude of the reception beam caused by the transmission beam in the θ2 direction and the amplitude of the reception beam caused by the transmission beam in the θ3 direction.
An amplitude comparison angle measurement for detecting a detailed position of the target 42 is performed.
Therefore, according to the radar device 130 of the present embodiment, when the target 42 exists near the boundary between two adjacent directions, the position of the target 42 can be detected in detail.

In the above-described embodiment, the angle measurement processor 132 is combined with the radar device 50 of the first embodiment. However, the present invention is not limited to this. 132 may be combined with the radar device according to any of the second to seventh embodiments.

Embodiment 9 FIG. Next, referring to FIG.
A ninth embodiment of the present invention will be described. FIG. 23 is a block diagram showing a radar apparatus 140 according to Embodiment 9 of the present invention. The radar device 140 of the present embodiment further includes a beam selection processor 142 in addition to the system configuration of the eighth embodiment. In the present embodiment, the output signal of the target detector 40 is supplied to the beam selection processor 142.

The radar apparatus 140 divides a monitoring area having a three-dimensional spread into a plurality of areas, and performs target detection processing by sequentially irradiating these areas with transmission beams. Inside such a monitoring area, a situation may occur in which a target is located at a boundary in three or more directions. The beam selection processor 142 can be used to determine if the target is likely to be located across three or more direction boundaries, from each of those directions.
Two directions for generating a reception beam having a large amplitude are selected. The angle measurement processor 132 performs amplitude comparison angle measurement in the same manner as in the eighth embodiment, based on the reception beams in the two directions selected as described above. Therefore, according to the radar apparatus 140 of the present embodiment, a target position can be detected with high accuracy by a simple process for a monitoring area having a three-dimensional spread.

[0106]

Since the present invention is configured as described above, it has the following effects. Claim 1
According to the described invention, the switching pattern of the irradiation direction of the transmission beam is periodically switched. When the target is located at the boundary between the two directions, the reception beams from the two directions always have substantially the same waveform regardless of the irradiation direction switching pattern. On the other hand, when the switching pattern of the irradiation direction of the transmission beam changes in a situation where the target exists at a position other than the boundary, the reception beams from the two directions do not always have the same waveform. Therefore, according to the present invention, highly accurate target detection can be performed without changing the frequency of the transmission beam.

According to the second aspect of the present invention, the sweep pattern of the transmission beam is periodically switched, and the reception beam is subjected to compression processing. In this case, it is possible to accurately discriminate a reception beam incident from a specific direction from a reception beam incident from an adjacent direction.
Therefore, according to the present invention, highly accurate target detection can be performed without greatly changing the frequency of the transmission beam.

According to the third aspect of the present invention, two adjacent
When the receiving beam is obtained from one direction, the irradiation direction of the transmitting beam is offset. By giving an offset to the irradiation direction of the transmission beam, the target existing at the boundary between two adjacent directions can be relatively moved to the vicinity of the center of the specific irradiation direction. Therefore, according to the present invention, highly accurate target detection can be performed without changing the frequency of the transmission beam.

According to the fourth aspect of the present invention, the code modulation pattern of the transmission beam is periodically switched, and
Demodulation processing is performed on the reception beam. In this case, it is possible to accurately discriminate a reception beam incident from a specific direction from a reception beam incident from an adjacent direction. Therefore, according to the present invention, highly accurate target detection can be performed without changing the frequency of the transmission beam.

According to the fifth aspect of the present invention, two adjacent
When the receiving beams are obtained from two directions, based on the Doppler frequency superimposed on the receiving beams,
It can be determined whether the cause of these two reception beams is the same target. Therefore, according to the present invention, highly accurate target detection can be performed without changing the frequency of the transmission beam.

According to the invention of claim 6, it is possible to prevent the transmission beam from being continuously irradiated in the adjacent direction. When a target exists at the boundary between two adjacent directions, the reception beams incident from those two directions have substantially the same waveform. On the other hand, according to the present invention, when different targets are present in two adjacent directions, different reception beams are incident from the two directions. Therefore, according to the present invention, highly accurate target detection can be performed without changing the frequency of the transmission beam.

According to the seventh aspect of the present invention, two adjacent
When the receiving beam is obtained from one of the two directions, a situation where the transmitting beam is not continuously irradiated in the two directions can be formed. When the transmission beam is not transmitted continuously in two adjacent directions, an existing target in those directions can be accurately detected. Therefore, according to the present invention, highly accurate target detection can be performed without changing the frequency of the transmission beam.

According to the eighth aspect of the present invention, two adjacent two
When receiving beams are obtained from two directions, angle measurement processing is executed based on the intensities of the two receiving beams.
Therefore, according to the present invention, when a target exists at a boundary between two adjacent directions, the position of the target can be accurately detected.

According to the ninth aspect of the present invention, when receiving beams are obtained from three or more spatially adjacent directions, an appropriate beam is selected from these receiving beams and angle measurement is performed. be able to. For this reason, according to the present invention, when a target exists at the boundary in three or more directions spatially adjacent to each other, the position of the target can be accurately detected by a simple process.

[Brief description of the drawings]

FIG. 1 is a block configuration diagram of a radar device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing the contents of a beam scanning pattern table used in the first embodiment.

FIG. 3 is a timing chart (part 1) for explaining the operation of the radar apparatus according to the first embodiment;

FIG. 4 is an example of a situation in which the timing chart shown in FIG. 3 can be obtained.

FIG. 5 is a timing chart (part 2) for explaining the operation of the radar apparatus according to the first embodiment;

FIG. 6 is a block diagram of a radar apparatus according to Embodiment 2 of the present invention.

FIG. 7 is a first example of a sweep pattern used in the second embodiment.

FIG. 8 is a second example of the sweep pattern used in the second embodiment.

FIG. 9 is a third example of the sweep pattern used in the second embodiment.

FIG. 10 is a waveform of a sweep pulse generated in the second embodiment.

FIG. 11 is a timing chart for explaining an operation of the radar apparatus according to the second embodiment.

FIG. 12 is a block diagram of a radar apparatus according to Embodiment 3 of the present invention.

FIG. 13 is a timing chart (part 1) for explaining the operation of the radar apparatus according to the third embodiment;

FIG. 14 is a diagram illustrating a situation realized with the operation of the third embodiment.

FIG. 15 is a timing chart (2) for explaining the operation of the radar apparatus according to the third embodiment;

FIG. 16 is a block diagram of a radar apparatus according to Embodiment 4 of the present invention.

FIG. 17 is a waveform of a code modulation pulse generated in the fourth embodiment.

FIG. 18 is a block diagram of a radar apparatus according to Embodiment 5 of the present invention.

FIG. 19 is a diagram for explaining the operation of the radar device according to the sixth embodiment.

FIG. 20 is a block diagram of a radar apparatus according to Embodiment 7 of the present invention.

FIG. 21 is a block diagram of a radar apparatus according to Embodiment 8 of the present invention.

FIG. 22 is a timing chart for explaining the operation of the radar apparatus according to the eighth embodiment.

FIG. 23 is a block diagram of a radar apparatus according to Embodiment 9 of the present invention.

FIG. 24 is a block diagram of a conventional radar device.

FIG. 25 is a diagram illustrating a situation in which a target exists near a boundary between two adjacent directions.

FIG. 26 is a timing chart for explaining the operation of a conventional radar device.

[Explanation of symbols]

12 timing controller, 16 transmitter, 18
Power divider, 20 phase shifter, 22 beam scanning controller, 24 power amplifier, 26 circulator, 28 element antenna, 30 transmit beam, 32 receive beam, 42, 68, 70, 7
2,74 goals, 50; 80; 90; 100; 11
0; 120; 130; 140 radar device, 52
Beam scan pattern table, 82 pulse compression pattern table, 84 sweep pulse generator, 8
6 pulse compression pattern table, 92 beam scanning angle offset controller, 102 code modulation pattern table, 104 modulation pulse generator, 106
Pulse compressor, 112 coherent integrator,
114 Doppler frequency determiner, 116 target determiner, 122 beam scanning pattern table, 1
32 Angle measurement processor, 142 Beam selection processor.

[Procedure amendment]

[Submission date] December 25, 1998 (1998.12.
25)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] FIG.

[Correction method] Change

[Correction contents]

FIG. 21

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] FIG.

[Correction method] Change

[Correction contents]

FIG. 23

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 5J070 AA14 AB08 AB09 AB11 AC01 AC02 AC06 AC11 AC13 AD09 AD10 AE04 AG03 AG08 AG09 AH02 AH23 AH31 AH33 AH34 AH39 AH50 AJ10 AJ13 AK13 AK22 BA01 BB02 BB05 BB21

Claims (9)

[Claims] 1. A transmission beam generating means, comprising: a phase shifter provided corresponding to each of a plurality of element antennas, and transmitting a transmission beam by electronically changing an irradiation direction to a plurality of directions sequentially; A provided for each of the element antennas
A / D converter, a beam former for receiving an output signal of the A / D converter, a receiving beam generating means for generating a receiving beam corresponding to each of a plurality of directions, and a switching of an irradiation direction of a transmitting beam A radiation pattern periodic switching means for periodically switching a pattern. 2. A transmission beam generating means, comprising: a phase shifter provided corresponding to each of a plurality of element antennas, and transmitting a transmission beam by electronically switching an irradiation direction to a plurality of directions; A provided for each of the element antennas
A / D converter, a beamformer for receiving an output signal of the A / D converter, a receiving beam generating means for generating receiving beams corresponding to each of a plurality of directions, A sweep pulse generating means for changing a sweep pattern, a sweep pattern switching means for switching the predetermined sweep pattern in synchronization with a switching time of a transmission beam irradiation direction, and a sweep pulse generating means for canceling a sweep pattern used by the sweep pulse generating means. A radar comprising: a pulse compression unit that changes a frequency of a reception beam in a compression pattern; and a filter that extracts a signal near a predetermined frequency from the reception beam whose frequency has been compressed by the pulse compression unit. apparatus. 3. A transmission beam generating means, comprising: a phase shifter provided corresponding to each of a plurality of element antennas, and transmitting a transmission beam by electronically changing an irradiation direction to a plurality of directions sequentially; A provided for each of the element antennas
A / D converter, a beam former for receiving an output signal of the A / D converter, a receiving beam generating means for generating a receiving beam corresponding to each of a plurality of directions, and receiving from two adjacent directions When a beam is available,
A beam scanning angle offset means for giving an offset of a predetermined angle smaller than a beam width in an irradiation direction of a transmission beam. 4. A transmission beam generating means comprising: a phase shifter provided corresponding to each of a plurality of element antennas, and transmitting a transmission beam by electronically switching an irradiation direction to a plurality of directions; A provided for each of the element antennas
A / D converter, a beam former for receiving an output signal of the A / D converter, a receiving beam generating means for generating a receiving beam corresponding to each of a plurality of directions, and a modulation for code-modulating the transmitting beam. A pulse generation unit, a code modulation pattern switching unit that switches the code modulation pattern in synchronization with a switching timing of a transmission beam irradiation direction, and a compression pattern for canceling the code modulation pattern used by the modulation pulse generation unit. A radar apparatus comprising: a pulse compression unit that demodulates a reception beam; and a filter that extracts a reference modulation signal from the reception beam demodulated by the pulse compression unit. 5. A transmission beam generating means, comprising: a phase shifter provided corresponding to each of a plurality of element antennas, and transmitting a transmission beam by electronically switching an irradiation direction to a plurality of directions; A provided for each of the element antennas
A / D converter, a beam former for receiving an output signal of the A / D converter, a receiving beam generating means for generating a receiving beam corresponding to each of a plurality of directions, Doppler frequency detection means for detecting a Doppler frequency superimposed on a corresponding reception beam, and when reception beams are received from two adjacent directions, based on the Doppler frequency superimposed on those reception beams, And a target determining means for determining whether or not the cause of the generation of the received beams is the same target. 6. A transmission beam generating means, comprising: a phase shifter provided corresponding to each of a plurality of element antennas, and transmitting a transmission beam by electronically switching an irradiation direction to a plurality of directions; A provided for each of the element antennas
A / D converter, a beam former for receiving an output signal of the A / D converter, a receiving beam generating means for generating a receiving beam corresponding to each of a plurality of directions, and continuously in adjacent directions. An irradiation direction switching unit that switches the irradiation direction of the transmission beam in a pattern in which the transmission beam is not irradiated. 7. A transmission beam generating means, comprising: a phase shifter provided corresponding to each of a plurality of element antennas, and transmitting a transmission beam by electronically switching an irradiation direction to a plurality of directions; A provided for each of the element antennas
A / D converter, a beam former for receiving an output signal of the A / D converter, a receiving beam generating means for generating a receiving beam corresponding to each of a plurality of directions, and receiving from two adjacent directions After the beam is received,
An irradiation pattern switching unit that changes a switching pattern of an irradiation direction of the transmission beam so that the transmission beam is not continuously irradiated in the two directions. 8. An angle measurement processor for performing angle measurement processing for obtaining details of a target existence angle based on an intensity ratio of the reception beams when reception beams are obtained from a plurality of adjacent directions. The radar device according to claim 1, wherein: 9. The apparatus according to claim 8, further comprising: a beam selecting unit that selects an optimum reception beam to be subjected to angle measurement processing when reception beams are received from three or more adjacent directions. The described radar device.