JPS61235779A - Radar distance measuring instrument - Google Patents

Abstract

PURPOSE:To prevent the erroneous distance measurement by unnecessary echoes by making preliminarily initial setting of a distance gate in accordance with the information on the alutitude measured by an external apparatus, the information on the angle of a radar antenna and the information on the pitch angle of a plane and making distance scanning around the set position. CONSTITUTION:A signal transmitter 2 which transmits high-frequency electromagnetic wave energy, a signal receiver 3 which receives the reflected electromagnetic wave, an antenna 1 for signal reception and transmission and a transmission-reception selector 4 are provided. A servocontrol mechanism which controls the distance gate by a gate circuit 5, an echo discrimination circuit 6, a reference time circuit 7 and a distance gate generating circuit 8 are constituted. The angle signal from the space horizontal plane obtd. by adding an altitude signal 21 from a radio altimeter or barometic altimeter 19, a pitch signal 22 from a plane pitch angle 20 and an antenna angle signal 23 from an antenna angle 18 is multiplied 17 by the angle signal and the distance gate is initially set at the time position corresponding to the predicted skew distance up to the target point indicated by an outputted initial set distance signal 24. The distance scanning is executed by a sweep circuit 25 in the narrow range around the initial set position.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a radar device for measuring ground distance mounted on an aircraft.

[Conventional technology]

Some conventional radar distance measuring devices have a configuration as shown in FIG.

In FIG. 2, a transmitter (2) that transmits high-frequency electromagnetic wave energy, a receiver (3) that receives reflected electromagnetic waves,
It is equipped with a single transmitting/receiving antenna (11) and a transmitting/receiving switch (4).

Furthermore, a gate circuit (5) for performing a distance gate on the received echo pulse using an electronic switch, this distance gate is capable of passing an echo pulse with a certain delay time,
Can be varied steplessly.

The echo pulses are passed through an echo discrimination circuit (6).

The position (delay time) of the distance gate is determined by converting the output voltage of the echo discrimination circuit into delay time by the reference time circuit (7).
This time position controls the distance gate position.

These gate circuits, echo discrimination circuits, reference time circuits,
The distance gate generation circuit (8) constitutes a servo mechanism that controls the distance gate.

When there is no echo pulse, the distance scanning of the receivable distance range is performed by the sweep circuit Qυ for scanning the distance gate.

Distance scanning by this sweep circuit is performed by a signal line (9) via a switch α1 when an echo pulse is received.

Switches to the output voltage of the echo discrimination circuit. Namely.

A servo loop is formed to control the distance gate, and distance information to the ground surface can be obtained from the position of the distance gate.

[Problem that the invention seeks to solve]

In the case of aircraft-mounted radar equipment, as shown in Figure 3,
Whenever there is a reflected wave from the ground surface that is received by the side lobe r1z of the radar antenna, this reflected wave from the ground surface is called an altitude line and appears at a distance that approximately coincides with the altitude of the aircraft.

FIG. 4 shows the received echo α◆ due to the main rope and the received echo α9 due to the tidal rope on the radar display.

Therefore, if the received echo from the main rope cannot be detected as described above, if a wide range distance scan is performed using the range gate, depending on the aircraft's altitude, attitude, antenna angle, and the condition of the shooting surface, the side rope may be detected. The received echo signal strength due to the side lobe may exceed the received echo signal strength due to the main rope, and the distance gate may measure the received echo position due to the side lobe, resulting in an incorrect distance measurement.

This invention was made to solve these problems, and instead of performing wide distance scanning, distance scanning is performed within a narrow range centered on a position where the distance gate is initially set in advance. The object of the present invention is to provide a radar distance measuring device that can prevent erroneous distance measurement due to side lobes.

[Means for solving problems]

The radar distance measuring device of the present invention initializes a distance gate in advance using altitude information provided by an external device, angle information of the radar antenna, and pitch angle information of the aircraft.
By distance scanning within a narrow range around this set position, a means for preventing distance measurement due to side lobes is realized.

[Operation] In this invention, as shown in FIG.
When the aircraft is heading toward target 69 at an angle α from the horizontal plane, and the altitude of the aircraft at this time is H, the oblique distance R to the target is Using the altitude information of the external device, the radar antenna angle information, and the pitch angle information of the aircraft, initial setting of the expected distance is performed by means of calculating the oblique distance R, and distance scanning is performed around the set distance. This prevents distance measurement due to side lobes.

〔Example〕

FIG. 1 is a system diagram showing a V-dar distance measuring device according to an embodiment of the present invention.

++) to a1 are exactly the same as the above-mentioned conventional device. αη is the distance gate command circuit, Q8 is the radar antenna angle signal source, α value is the radio altimeter or barometric altimeter, and ■ is the aircraft attitude angle (pitch angle) signal source.

In the radar distance measurement device configured as described above, from the spatial horizontal plane which is the sum of the altitude signal Qυ from the radio altimeter or barometric altimeter, the aircraft pitch angle signal (to), and the vertical antenna angle signal (to) of the radar antenna. The initial setting distance signal c! is output by multiplying the angle signal by the altitude signal. The distance gate is initially set to a time position corresponding to the predicted oblique distance to the target point indicated by 4, and the sweep circuit (c) performs distance scanning from a long distance to a short distance in a narrow range around this initial setting position. conduct. When matched with the echo received by the main rope, an accurate distance measurement is made by the radar distance measuring device.

〔Effect of the invention〕

As described above, the present invention replaces the wide distance scanning of conventional radar distance measuring devices.

Initialize the distance gate to the expected distance position.

In addition, by scanning the distance within a narrow range, it is possible to prevent erroneous distance measurement due to unnecessary echo pulses such as received echoes due to side lobes, thereby making it possible to provide an effective distance measuring device.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a radar distance measuring device showing an embodiment of the present invention, FIG. 2 is a system diagram of a conventional radar distance measuring device,
FIG. 3 is an explanatory diagram of received echoes by the main rope and received echoes by the side ropes. FIG. 4 is a diagram illustrating received echoes from the main rope and side ropes on the radar display, and FIG. 5 is a diagram illustrating the relationship between altitude and angle during target point ranging. In the figure, (1) is the transmitting and receiving antenna, (2) is the transmitter, (
3) is a receiver, (4) is a transmitter/receiver switch, (5) is a gate circuit, (6) is an echo discrimination circuit, (7) is a reference time circuit,
(8) is the distance gate generation circuit, Ql is the switch, (1
11 is the sweep circuit, αη is the distance gate command circuit, or antenna angle, f19 is the radio altimeter or barometric altimeter, (to) is the aircraft pitch angle, cll) is the altitude signal, @ is the pinch signal, (c) is the antenna angle C24 is an initial setting distance signal, @ is a sweep circuit, and (to) is a distance scanning signal centered on the initial setting. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] A radar equipped with a servo mechanism that transmits electromagnetic waves to the ground surface, receives the reflected electromagnetic waves, discriminates the resulting echo pulses, and controls a distance gate at a time position that makes the discriminated output voltage zero. In a distance measuring device, a means for initially setting a distance gate at an echo pulse reception distance position predicted in advance based on altitude information from an external device such as a radio altimeter or a barometric altimeter, and a means for sweeping the distance gate around the initial setting position. A radar distance measuring device characterized by comprising: