JP2000171548A - Pulse radar apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure the detecting range of a pulse radar apparatus so as to control a blind distance properly. SOLUTION: A pulse-width adjusting device 7 outputs a pulse-width command signal 8 on the basis of distance information 6 on an object detected by a detector 5. A pulse-width modulator 2 pulse-modulates waves, to be modulated, from an oscillator 1, and it outputs radar transmitting waves in a pulse width corresponding to the pulse-width command signal 8. Since the modulation pulse width of the transmitting waves is changed according to a change in a distance to an object to be detected, a blind distance at which the object cannot be detected can be controlled properly while a detecting distance is being ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse radar device, and more particularly to a pulse radar device having an improved object detection range.

[0002]

2. Description of the Related Art Conventionally, in a pulse radar apparatus (monostatic radar) which uses a single antenna for both transmission and reception, an oscillator for generating and outputting a modulated wave and a radar for performing pulse modulation of the modulated wave are provided. A pulse modulator that outputs as a transmission wave, a transmission / reception switch that switches between a transmission wave and a reception wave, an antenna that transmits a transmission wave to space and receives a reflection wave reflected from an object, and a reception reflection wave. It comprises a detector for detecting the position and the like of the object, and a display for displaying the position and the like of the object.

The detection distance (target detection capability) of an object of such a pulse radar device is proportional to the energy of a transmitted wave radiated into space, and the detection distance is usually secured by increasing the modulation pulse width. It is configured as follows. In a monostatic radar, when the modulation pulse width is increased, the undetectable region (blind distance) increases. Therefore, the long pulse width transmission wave and the short pulse width transmission wave having different modulation pulse widths are alternately transmitted and blind. There is known a method capable of detecting a short distance within a distance (see Japanese Patent Application Laid-Open No. 9-90022).

[0004]

In the above-described pulse radar apparatus, if the modulation pulse width is increased in order to secure the object detection distance, the reflected wave can be received during the transmission, so that the object cannot be detected by the modulation pulse width. However, there is a disadvantage that the blind distance, which is a distance range in which detection is not possible, becomes long.Moreover, the pulse radar apparatus using transmission waves having different pulse widths has a complicated signal processing, and the repetition time of transmission of transmission waves is long. It is difficult to accurately grasp the movement of the target object.

(Object of the Invention) It is an object of the present invention to provide a pulse radar apparatus capable of controlling a transmission wave to an optimum pulse width according to the distance of an object.

An object of the present invention is to provide a pulse radar apparatus capable of shortening a blind distance corresponding to a pulse width in which an object cannot be detected while securing a detection distance.

[0007]

According to the present invention, there is provided a pulse radar apparatus comprising: an oscillator for outputting a modulated wave; a pulse modulator for performing pulse modulation of the modulated wave and outputting as a transmission wave;
A pulse having a transmission / reception switch that switches between a transmission wave and a reception wave, an antenna that transmits a transmission wave to space and receives a reflected wave from an object, and a detector that detects distance information of the object from the received reflected wave The radar apparatus further includes a pulse width adjuster that controls a modulation pulse width of the pulse modulator according to the distance information of the object detected by the detector according to the magnitude of the distance information.

The pulse width adjuster of the present invention controls the modulation pulse width to increase as the distance to the object increases, and to shorten the modulation pulse width when the distance to the object approaches the blind distance or less. It is characterized by doing.

In the pulse width adjuster of the present invention, the modulation pulse width is controlled in an initial state by setting a modulation pulse width at an upper limit of a detection range of a predetermined apogee, and after detecting an object, the distance from the object is detected. Either control to shorten the modulation pulse width when approaching the blind distance or less, or set it to the lower limit modulation pulse width of the predetermined perigee detection range in the initial state, and after detecting the object, The pulse width is controlled to be increased when the distance moves in the direction of the apogee beyond the blind distance.

(Operation) The pulse width adjuster controls the pulse modulator based on the distance information to the object detected by the detector, and controls the modulated pulse width of the transmission wave to an appropriate value according to the distance to the object. .

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a radar apparatus according to the present invention will be described in detail with reference to the drawings. FIG.
FIG. 1 is a block diagram showing an embodiment of the present invention. The radar apparatus according to the present embodiment includes an oscillator 1 that generates and outputs a modulated wave of a radio frequency, a pulse modulator 2 that performs pulse amplitude modulation with a constant repetition, and a transmission / reception switch 3 that switches between transmission and reception of an antenna. , Directional antenna 4
A detector 5 for calculating a distance or the like by correlating a transmission wave and a reception wave, a pulse width adjuster 7 for controlling a modulation pulse width of the pulse modulator 2, and a display 9 for displaying a detected object. It is configured.

The oscillator 1 generates a radio frequency transmission wave and outputs it to the pulse modulator 2. The pulse modulator 2 performs pulse modulation on the transmission wave and outputs a pulse-like amplitude modulation (pulse modulation signal). The pulse-modulated signal output from the pulse modulator 2 is transmitted to the antenna 4 via the transmission / reception switch 3 and transmitted to the space as a radar transmission wave. When an object is present, the transmission wave transmitted from the antenna 4 is reflected by the object, and is received by the antenna 4 as a reflected wave. The reflected wave received by the antenna 4 is sent to the detector 5 via the transmission / reception switch 3 as a received wave. Transmission / reception switch 3
Is switched to output the pulse modulated signal from the pulse modulator 2 to the antenna 4 at the time of transmission, and to output the received wave from the antenna 4 to the detector 5 at the time of reception. When a received wave is input, the detector 5 calculates the position and the like of the object by calculating a phase difference between the transmitted wave and the received wave, and among the calculated information,
Distance information 6 indicating the distance between the radar device and the object is sent to the pulse width adjuster 7. The pulse width adjuster 7 calculates the pulse width of the pulse modulation according to the distance to the object based on the input distance information 6, and sends a pulse width command signal 8 to the pulse modulator 2. In the pulse modulator 2, the transmission wave from the oscillator 1 is pulse-modulated to the pulse width of the command value based on the pulse width command signal 8. The calculation result of the detector 5 is also sent to the display 9 to display the position and the like of the object. In addition, as the pulse modulator 2 and the pulse width adjuster 7, for example,
A variable pulse width pulse generator can be provided in the pulse width adjuster 7 to output the pulse signal as a pulse width command signal. Thus, the amplitude of the output of the transmitter 1 can be controlled to perform modulation.

Next, the control operation of the pulse width in the pulse modulation of the present embodiment will be described with reference to the drawings.
FIG. 2 is a diagram showing a signal waveform indicating a pulse width in pulse modulation according to the present embodiment. First, when the pulse width of the modulated pulse by pulse modulator 2 and tau _1, blind distance R _B1 that can not detect the object is dependent on the pulse _{width, R B1 = Cτ 1/2} (C is the speed of light) Becomes
At this time, if the distance R ₁ to the object is larger than the blind distance R _B1 , the object enters the detectable range of the pulse radar device, and the distance measurement and the like are performed normally.

Next, when the object approaches and becomes the distance R ₂ (<R ₁ ), the pulse width adjuster 7 determines the detection distance R ₂ based on the distance information 8 from the detector 5 to the blind. In order not to be smaller than the distance, the pulse modulator 2 is controlled so that the pulse width becomes τ ₂ (<τ ₁ ) smaller than τ ₁ according to the approach of the object, and the blind distance is changed from RB 1 to R _B1.
Shortening the _{B2 (R B2 = Cτ 2/} 2).

When the object moves away, the pulse width adjuster 7 sets the pulse width to τ ₃ (> τ ₁ ) as the object moves away from the pulse modulator 2 based on the distance information 8 from the detector 5. _RB3 (R _B3 = C
controlling the τ _3/2). The distance to the object is R ₃ (> R ₁ )
Even if it becomes longer, the detectable distance can be ensured by increasing the energy of the transmission wave by setting the pulse width to τ ₃ wide.

In the above-described embodiment, the description has been given of the control of the pulse width adjuster 7 from the state after the detection of the target object. Either a short pulse width or a long pulse width can be set, and the length of the pulse width is controlled in accordance with the distance or the change with time according to the distance information after the object is detected from the detector 3. be able to. In addition, the control in the pulse width adjuster is specifically performed such that the pulse width is increased as the distance to the object increases, and the pulse width is shortened when the distance to the object approaches the blind distance or less. I do. Also, the control from the initial state is started from the setting of the detection range of a predetermined apogee, and after detecting the object, when the distance to the object approaches the blind distance or less, control is performed to shorten the pulse width, or In the state, the detection range may be set to a predetermined perigee, and after detecting the object, the pulse width may be controlled to be increased when the distance from the object to the apogee is longer than the blind distance.

[0017]

As described above, according to the radar apparatus of the present invention, the pulse width increases as the distance to the object increases, and the pulse width decreases as the distance to the object approaches the blind distance or less. The detection range can be secured even when the distance to the object is large, and even when the distance to the object is small, the detection range can be expanded by shortening the blind distance. It is possible.

Further, according to the present invention, since the blind distance is shortened while securing the detection distance in accordance with the distance of the object, the detection of the detection position and the like can be performed without losing a rapidly moving flying object or the like. It is possible to surely grasp the situation.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a signal waveform of each unit according to the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Oscillator 2 Pulse modulator 3 Transmission / reception switch 4 Antenna 5 Detector 6 Distance information 7 Pulse width adjuster 8 Pulse width command signal 9 Display

Claims (5)

[Claims] An oscillator for outputting a modulated wave; a pulse modulator for performing pulse modulation of the modulated wave and outputting the same as a transmission wave; a transmission / reception switch for switching between the transmission wave and a reception wave; In the pulse radar device having an antenna that transmits a space and receives a reflected wave from an object, and a detector that detects distance information of the object from the received reflected wave, according to the distance information of the object detected by the detector A pulse width adjuster for controlling a modulation pulse width of the pulse modulator in accordance with a magnitude of the distance information. 2. The pulse width adjuster controls the modulation pulse width to increase as the distance to the object increases, and to reduce the modulation pulse width when the distance to the object approaches the blind distance or less. The pulse radar device according to claim 1, wherein: 3. The pulse radar apparatus according to claim 2, wherein the control range of the modulation pulse width of the pulse width adjuster has an upper limit and a lower limit. 4. The pulse width adjuster is set to a modulation pulse width at an upper limit of a detection range of a predetermined apogee in an initial state, and when a distance from an object approaches a blind distance or less after detection of the object. 2. The pulse radar apparatus according to claim 1, wherein control is performed to shorten the modulation pulse width. 5. The pulse width adjuster is set to a modulation pulse width of a lower limit of a detection range of a predetermined perigee in an initial state, and after an object is detected, a distance from the object to an apogee distance equal to or longer than a blind distance. 2. The pulse radar apparatus according to claim 1, wherein the pulse radar is controlled so as to increase the pulse width when it moves.