JP2002022819A - Electronic scanning radar apparatus and goniometric processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic scanning radar apparatus which is provided with a function identical to that of a monopulse system and which reduces the scale of hardware so as to be made low-cost due its reduction. SOLUTION: From a multipath goniometric processor 6, information on a measuring direction is given to a phase-shift-amount controller 2. Offset amounts in the horizontal direction and the vertical direction of a reception beam with reference to the direction of the measuring center are set. Thereby, in an antenna 1, a phase shift amount with reference to the direction of the measuring center is set in a transmission, and phase shift amounts which are offset in the horizontal direction and the vertical direction are changed over and set sequentially in every PRI with reference to the direction of the measuring center in a reception. A reception signal which is obtained by every PRI is collectively processed by the processor 6, and an error in an angle in a target direction with reference to the measuring center is calculated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar device for detecting a target by using an electronic scanning antenna, and more particularly to a small radar device for an airborne vehicle and a radar for an air bone, which are required to be reduced in size and cost. It relates to a device suitable for a device.

[0002]

2. Description of the Related Art As is well known, in a radar apparatus,
Target information (distance, angle, etc.) is obtained by irradiating radio waves in the target direction by itself and processing signals reflected by the target. Among these radar systems, the monopulse system is currently most frequently used as a method of calculating a target angle error.

FIG. 5 shows an example of a radar apparatus using an electronic scanning antenna using a monopulse system. In FIG. 5, reference numeral 11 denotes an electronic scanning antenna, and a phase shift amount controller 12
The transmission beam and the reception beam can be oscillated in the azimuth direction and the height direction according to the phase shift amount from the signal. This antenna 11
Is supplied through a comparator (distribution / combiner) 13.

[0004] The transmitter 14 generates a transmission pulse at a constant repetition period. This transmission pulse is applied to the circulator 15
And is radiated from the antenna 11 in a designated direction. If there is a target object in this direction,
The transmission pulse is reflected by the target, and the reflected pulse returns to the electronic scanning antenna 11.

[0005] Here, the monopulse system is a system for detecting an angular error by using a pair of two partially overlapped antenna beams. When detecting an angular error in both the azimuth and the elevation, as shown in FIG. 5, for example, the radiating element of the antenna 11 is divided into four in the azimuth direction and the elevation direction, and four antenna beams (A, B in FIG. 5) , C, D)
To form

The outputs A to D of the radiating elements forming these four antenna beams are supplied to a comparator 13.
The comparator 13 combines the radiating element outputs of the respective areas A to D to obtain a sum signal (Σ) and a difference signal (Δ). As the difference signal (Δ), an azimuth angle difference signal (ΔAz) and an elevation angle difference signal (ΔEl) are generated. The sum signal (Σ) is supplied to the three-channel receiver 16 via the circulator 15,
The azimuth angle difference signal (ΔAz) and the elevation angle difference signal (ΔEl) are directly supplied to the three-channel receiver 16 to be video-detected, respectively, and supplied to the angle measurement processing unit 17.

FIG. 6 shows a specific angle measurement calculation process. The beam patterns representing the angle-gain characteristics in the azimuth direction and the elevation direction are respectively a Σ pattern (solid line) and a Δ pattern (dotted line) as shown in FIG. In the angle measurement calculation processing,
Using this characteristic, a method of dividing the difference signal (Δ) by the sum signal (Σ), that is, normalizing the difference signal (Δ) is used. At this time, assuming that the angle error voltage is εv, εv = Δ / Σ, and the angle error ε0 can be obtained by applying the monopulse S-curve characteristic as shown in FIG. 6B. Therefore, assuming that the measurement center direction is θa and the angle error obtained by the monopulse method is ε0, the target direction θ0 is represented by θ0 = θa + ε0.

In the above monopulse system, since it is necessary to simultaneously process the sum and difference signals of one received pulse, three receiving systems are usually required as shown in FIG. 5 (azimuth direction and high and low directions). In a system that processes directions in a time-division manner, there may be two reception systems.)

[0009] In addition to the monopulse system, a relatively old type of radar employs a system in which an antenna beam is continuously scanned near a target and the received signal intensity is averaged to perform angle measurement. A typical example is a conical scan method.

However, in these conventional systems, only one receiving system (sum signal system) is required, which has the advantage of simplifying the hardware, but has the disadvantage that it is susceptible to the temporal fluctuation of the received signal. There is. This is because the transmission / reception beam continuously scans the vicinity of the target, so that the center direction of the transmission beam changes every moment and is always in a different direction.

In this case, if a complicated clutter exists near the target, the radio wave reflected from the clutter and the radio wave reflected from the target are synthesized and incident. For this reason, when the radio wave reflected from the clutter changes significantly depending on the beam scanning direction, the received signal also changes accordingly.

[0012]

As described above, the angle error in the current radar apparatus is generally calculated by the monopulse system which is hardly affected by the fluctuation element of the received signal strength. However, there are disadvantages that three receiving systems are required, the hardware scale is large, and the product price is accordingly high.

The angle measurement by the conventional beam scanning method such as the conical scanning method can simplify the hardware, but the received signal intensity of the radio wave reflected from the target because the transmitting beam always changes its radiation direction. Fluctuates over time. Therefore, there is a disadvantage that the angle measurement accuracy is deteriorated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has the same function as that of the monopulse system, and can reduce the scale of hardware and thereby reduce the price. It is an object to provide an apparatus and an angle measurement processing method.

[0015]

In order to achieve the above object, an electronic scanning radar apparatus according to the present invention comprises a transmitting beam,
An electronic scanning antenna for forming a reception beam in a specified direction; and forming the transmission beam in a specified measurement direction with respect to the electronic scanning antenna. Beam forming control means for controlling the measurement center point so as to be switched and symmetrically provided with an offset for any one of the elevation directions, and the reception signal of the reception beam switched for each transmission repetition cycle by this means. Angle measurement means for obtaining an angle error in a target direction with respect to the measurement center point from the received signals of the beams having a symmetrical relationship.

In particular, in the angle measurement processing method according to the present invention, the transmission beam is formed in a designated measurement direction, and the reception beam is formed in at least one of the horizontal direction and the elevation direction at every repetition period of the transmission pulse. The method is characterized in that a measurement center point is formed by being switched symmetrically with an offset, and an angle error in a target direction with respect to the measurement center point is obtained using a reception signal of a reception beam having a symmetric relationship.

That is, according to the present invention, the transmission beam is always radiated in a fixed direction by switching the radio wave radiation direction of the transmission beam and the reception beam, the temporal fluctuation of the reception signal is reduced as much as possible, and the reception signal is comprehensively processed. And angle measuring means for calculating an angle error.

In particular, the difference from the angle measurement method using the old beam scanning method is that the transmission beam direction is always directed toward the center of the measurement in order to minimize the temporal fluctuation of the radio wave reflected from the target as described above. In this case, only the reception beam is received at an angle offset from the transmission beam by a predetermined value.

In the angle measuring method having the above means, it is possible to calculate an angle error using only a single receiving system (sum signal system), thereby reducing the hardware scale of the radar device. Accordingly, miniaturization and cost reduction can be realized.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows the configuration of an electronic scanning radar apparatus according to an embodiment of the present invention. In FIG. 1, 1
Is an electronic scanning antenna capable of switching the beam direction at high speed by transmission / reception, and its beam forming direction is determined by the phase shift amount given from the phase shift amount controller 2. When the measurement direction information is given, the phase shift amount controller 2 sends the phase shift amount corresponding to the direction to the antenna 1.

The transmitter 3 generates and outputs a transmission pulse at a constant period. The transmission pulse is sent to the antenna 1 via the circulator 4 and is transmitted in a direction corresponding to the phase shift amount from the phase shift amount controller 2. Sent out. The antenna 1 forms a reception beam corresponding to the phase shift amount from the phase shift amount controller 2, and upon receiving the reflected wave of the transmission pulse, combines all the radiating element outputs to generate a sum signal (Σ). . This sum signal is sent to the one-channel receiver 5 via the circulator 4 and video-detected. The output of the receiver 5 is supplied to a multi-pulse angle measurement processing device 6.

This multi-pulse angle measurement processing device 6 has the configuration shown in FIG.
As shown in (2), the phase shift amount controller 4 is instructed to form the transmission beam in the designated direction, and further, in the horizontal and vertical directions so as to be point-symmetric with respect to the measurement center T of the transmission beam. Receive beam A, B, C, D with offset
Is switched at the transmission repetition period (PRI) as shown in FIG. Then, video signals obtained by the respective receiving beams A to D are sequentially captured and stored, and a target angle in the horizontal direction is obtained from the video signals of the receiving beams A and B having an offset in the horizontal direction. From the video signals of the receiving beams C and D having

The processing operation of the above configuration will be described below.

First, as an initial setting, information on the measurement direction (or direction, if the existence of the target is known) is given from the multi-pulse angle measurement processing device 6 to the phase shift amount controller 2, and the measurement center T Are set in the horizontal and vertical directions of the reception beams A to D with respect to the direction of. This allows
In the antenna 1, the phase shift amount corresponding to the direction of the measurement center T is set at the time of transmission, and the phase shift amount offset horizontally and vertically with respect to the direction of the measurement center T at the time of reception is sequentially switched for each PRI. Is set.

The processing within the first PRI is as follows. First, a phase shift amount capable of forming a beam in the direction of the measurement center T is set to the electronic scanning antenna 1, and power is supplied from the transmitter 3 to the electronic scanning antenna 1, so that a transmission wave is directed toward the measurement center T in space. Radiate. Next, at the time of reception, immediately after the end of the transmission period, the amount of phase shift capable of forming a beam in the direction A shifted from the measurement center T by a predetermined angle horizontally leftward is set in the electronic scanning antenna 1 and the reflection from the target is set. Receive the waves. The received wave is frequency-converted by the receiver 5 and video-detected, and then input to the multipath angle measurement processing device 6, where it is temporarily stored as a received signal Sa.

In the next PRI processing, the transmission beam is
Radio waves are emitted toward the same measurement center T as RI. At the time of reception, the phase shift amount capable of forming a beam in the B direction, which is shifted from the measurement center T, which is point-symmetric to the previous PRI (the reference point at this time is the measurement center T), by a predetermined angle in the horizontal right direction, is calculated. The multi-pulse angle measurement processor 6 sets the scanning antenna 1 to receive a radio wave reflected from the target, and stores the received signal as Sb.

In the next PRI processing, the transmission beam is
Radio waves are emitted toward the same measurement center T as RI. At the time of reception, C deviated from the measurement center T by a predetermined angle in the vertical direction
Electronic scanning antenna 1
And the radio wave reflected from the target is received, and the received signal is stored in the multi-pulse angle measurement processor 6 as Sc.

In the next PRI processing, the transmission beam is
Radio waves are emitted toward the same measurement center T as RI. At the time of reception, the phase shift amount is set so that the beam can be formed in the D direction which is shifted by a predetermined angle from the measurement center T, which is a point symmetrical direction with respect to the previous PRI (the reference point at this time is the measurement center T), in the high-low direction. Is set in the electronic scanning antenna 1, the radio wave reflected from the target is received, and the received signal is stored in the multi-pulse angle measurement processor 6 as Sd.

In the multi-pulse angle measurement processing device 6,
The target direction M is measured from the beam reception signals Sa to Sd by the following method. First, the patterns of the receiving beams A and B in the azimuth direction are bilaterally symmetric with respect to the pattern (solid line) of the transmitting beam directed to the measurement center T, as shown in FIG. For this reason, assuming that the reception signal output voltages of the reception beams A and B are Sa and Sb, the angle error voltage εhv in the target direction can be expressed as εhv = (Sa−Sb) / (Sa + Sb). An S-shaped curve characteristic as shown in FIG. 4B is obtained between the angle error and the angle error voltage.
By applying the angle error voltage εhv to this characteristic, the angle error ε0
, And adding the angle error εh0 to the direction θha of the measurement center T as in the following equation, the target horizontal direction angle θh0 can be obtained.

Θh0 = θha + εh0 By performing the same angle measurement processing using the reception signal output voltages Sc and Sd of the reception beams C and D, the target elevation angle θv0 is obtained.
Can be requested. Therefore, the target direction M can be obtained by combining the values of both angles.

Therefore, according to the above configuration, all PRIs
By radiating radio waves in the direction of the measurement center T, which is a certain direction, temporal fluctuations of the received signal S can be reduced as compared with a conventional beam scanning method such as a conical scanning method. In addition, this series of transmission / reception operations is repeated,
By comprehensively processing the reception signal S obtained from the series of operations, the angle error ε between the point of the measurement center T and the target direction M can be measured.

[0033]

As described above, according to the present invention, the electronic scanning type radar apparatus and the angle measurement processing which have the same function as the monopulse method, and which can also reduce the hardware scale and the accompanying price. A method can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an electronic scanning radar apparatus according to an embodiment of the present invention.

FIG. 2 is a pattern layout diagram showing a pattern forming direction of a transmission beam and a reception beam of the embodiment.

FIG. 3 is an exemplary timing chart showing switching processing of a reception beam forming direction in the embodiment;

FIG. 4 is an exemplary view for explaining the contents of angle measurement processing according to the embodiment;

FIG. 5 is a block diagram showing a configuration of a conventional electronic scanning radar apparatus using a monopulse system.

FIG. 6 is a view for explaining the content of angle measurement processing by the monopulse method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electronic scanning antenna 2 ... Phase shift amount controller 3 ... Transmitter 4 ... Circulator 5 ... 1 channel receiver 6 ... Multi-pulse angle measurement processing apparatus 11 ... Electronic scanning antenna 12 ... Phase shift amount controller 13 ... Comparator (distribution) 14) Transmitter 15 ... Circulator 16 ... Three-channel receiver 17 ... Angle measurement processor

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kenichi Mori 18-32 A-204, 1-Fuchinobe, Sagamihara-shi, Kanagawa (72) Inventor Toshiya Ueda 1 Kosuka-Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Corporation In the Toshiba Komukai Plant (72) Inventor Satoshi Nakamura 1 in Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Inside the Toshiba Komukai Plant Co., Ltd. Address Co., Ltd. Toshiba Komukai Plant F-term (reference) 5J070 AB01 AC02 AC11 AD07 AD10 AD06 AF06 AK40

Claims (2)

[Claims] An electronic scanning antenna for forming a transmission beam and a reception beam in a designated direction, and forming the transmission beam in a designated measurement direction for the electronic scanning antenna, and transmitting the reception beam to a transmission pulse. Beam forming control means for controlling at least one of the horizontal direction and the height direction at every repetition cycle to form a measurement center point by symmetrically giving an offset and switching the measurement center point. An electronic scanning radar apparatus comprising: an angle-measuring unit that fetches a reception signal of a reception beam to be switched and obtains an angle error in a target direction with respect to the measurement center point from the reception signal of the beam having a symmetrical relationship. 2. A transmission beam is formed in a designated measurement direction, and a reception beam is symmetrically offset from a measurement center point in at least one of a horizontal direction and a height direction for each repetition period of a transmission pulse. An angle measurement processing method for determining an angle error in a target direction with respect to a measurement center point using reception signals of reception beams having a symmetrical relationship.