JP3153076B2 - Device for detecting objects above - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is for detecting the presence or absence of an object above an installed antenna, such as an aircraft or a vehicle on the ground, and particularly for detecting the natural frequency of a microwave band radiated from the ground. The present invention relates to a device for detecting an object located above, which detects the presence or absence of an object located above using a reflected wave of a thermal noise reflected by an object located above.

[0002]

2. Description of the Related Art At an airfield, it is extremely important to determine the presence or absence of an object such as a vehicle or a vehicle on the course of an aircraft from the viewpoint of safe operation. This type of conventional device emits radio waves from a directional antenna embedded in the ground, like a radar, toward the sky in a specific direction, and reflects the radio waves reflected by objects above this radio wave to the ground as well. The reception is performed using a reception antenna that is embedded and disposed, and the presence or absence of an object above the antenna is determined based on the presence or absence of a reflected radio wave.

[0003]

In the conventional apparatus as described above, the reciprocating distance to the object and the shape, material, Radio waves having appropriate power according to the size and the like must be emitted from the directional antenna. Therefore, in general, a considerably large power is required as the power of the emitted radio wave, and the apparatus including the transmitting means becomes large in size and consumes a large amount of power. This enlargement makes the device expensive, and also has the disadvantage that the life and reliability of the device itself are low due to the large power consumption. In addition, there is also a problem that mutual interference becomes a problem in emitting the radio waves, and legal permission is required, thereby increasing the burden on the operator.

The present invention has been made in order to improve the above-described problems of the conventional apparatus. Natural heat noise radiated from the ground is rejected by an object located above without emitting radio waves from the apparatus itself. It is an object of the present invention to provide a device for detecting an object located above, which detects the reflected wave thus detected to determine the presence or absence of an object located above.

[0005]

In order to achieve the above object, an object detecting apparatus according to the present invention is arranged such that a directional antenna is arranged on the ground toward the sky, and natural heat radiated from the ground is provided. The reflected wave reflected by the object above which the noise is received is received, and the output of the noise radio wave received by this directional antenna and the output of the non-reflection terminator at the same environmental temperature as the ground are alternately switched by the switch means. To the amplifying means, and convert the input AC component of the amplifying means by the switching of the switch means into a signal corresponding to the magnitude thereof,
By comparing this signal with a preset reference value by a comparing means, it is configured to determine the presence or absence of an object above the directional antenna.

A good conductor reflector is arranged obliquely upward, and the directional antenna is arranged facing the good conductor reflector so that the antenna directivity reflected by the good conductor reflector faces the sky. May be.

[0007]

[Operation] The output of a directional antenna that receives a reflected wave of natural thermal noise radiated from the ground and the output of a non-reflection terminator having the same environmental temperature as the ground are alternately given to an amplifying means. Since the signal corresponding to the magnitude of the component is compared with a preset reference value, the magnitude of the natural thermal noise radiated from the ground due to the change in environmental temperature and the thermal noise generated in the device Can be canceled, and the determination of the presence or absence of an object in the upper part can be accurately performed. Then, the natural thermal noise radiated from the ground is used to determine the presence or absence of an object above using the reflected wave reflected by the object above, so that the device itself does not emit radio waves and the device can be downsized. Power consumption is low. Further, since radio waves are not emitted, even if a plurality of devices are arranged in close proximity, they do not interfere with each other and malfunction.

If a good conductor reflecting plate directed obliquely upward is used, the directivity direction of the directional antenna can be reflected by the good conductor reflecting plate and directed to the sky, so that the degree of freedom of arrangement of the directional antenna is extremely high. I can do it.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a block circuit diagram of an embodiment of a device for detecting an object located above according to the present invention, and FIG.
FIG. 3 is a diagram illustrating an arrangement of a directional antenna, and FIG. 3 is a waveform diagram in the circuit of FIG.

First, as shown in FIG. 1, a directional antenna 10 is buried in the ground 14 toward the sky, and its output is given to one terminal a of a switch means 12. The other terminal b of the switch means 12 is connected to the ground 1
The output of the anti-reflection terminator 16 which is at the same environmental temperature as 4 is provided. Then, the output of the selection terminal c of the switch means 12 is given to the low noise amplifying means 18 and appropriately amplified,
Further, it is provided to the detection means 20 and detected. And
In the detection output, the DC component is blocked by the capacitor 22, only the AC component is supplied to the rectifier 24 and rectified, further smoothed by the smoother 26, converted into a signal corresponding to the magnitude of the AC component, and compared. A means 28 is provided. The comparison means 28 is supplied with a preset reference voltage Vs from the reference voltage means 30, and the comparison means 28 outputs a determination signal. The switch means 12 is controlled by the switch control means 32 so that the terminals a and b are alternately selected as the selection terminal c. Further, the determining means 34 is constituted by the capacitor 22, the rectifying means 24, the smoothing means 26, the comparing means 28 and the reference voltage means 30.

Here, as shown in FIG. 2, the directional antenna 10 is directed toward the sky such that an object 42 such as a mountain, a tree, or a building, which is not to be detected, is not included in the directional range. Be placed.

In such a configuration, the directional antenna 10
The relationship between the noise temperature T ₁ [Kelvin] of the thermal noise in the microwave band received at the above and the power P output from the detection means 20 is represented by P = (T ₁ / T + F−1) KTBG. Here, T [Kelvin] is the noise temperature due to the environmental temperature, K is the Boltzmann constant [Joule / Kelvin], B is the reception bandwidth [Hz] of the entire apparatus, and G is the low noise amplifier 18. This is the amplification gain.

Therefore, while the selection terminal c of the switch means 12 is connected to the terminal b, the output of the non-reflection terminator 16 is given to the low-noise amplifying means 18. Since the temperature is the same as the ambient temperature, the output is T [Kelvin], and the output power P ₀ is P ₀ = FKTBG.

While the selection terminal c of the switch means 12 is connected to the terminal a, the output of the directional antenna 10 is supplied to the low-noise amplifying means 18, but it is assumed that no object exists in the directional range. For example, only a slight spatial background thermal noise in which natural thermal noise radiated from the ground 14 is reflected by the air in the air is input to the directional antenna 10. The thermal noise generated in the device itself consisting of the directional antenna 10, the switch means 12, the low noise amplifying means 18 and the detecting means 20 is:
The size can be reduced by appropriately designing and manufacturing the device, and the total value T _A0 [Kelvin] of the noise temperature of the thermal noise of the device itself and the spatial background thermal noise can be sufficiently reduced. For example, T _A0 ≦ 60 [Kelvin] can be suppressed under the condition that T is 300 [Kelvin]. The power P _A0 output in this case is represented by P _A0 = (T _A0 / T + F−1) KTBG.

If an object 40 exists above the directivity range of the directional antenna 10 while the selection terminal c of the switch means 12 is connected to the terminal a, the object 40 above this causes the ground 14 to Is reflected by the directional antenna 10, and the total value T _A1 [Kelvin] of the noise temperature with the thermal noise of the device itself is T
_A0 <T _A1 <T, and the output power P
_A1 is represented by P _A1 = (T _A1 / T + F−1) KTBG.

[0016] Thus, for switching of the switching means 12 such shown in FIG. 3 (A), as shown in FIG. 3 (b), the output from the detection means 20, _{P 0} and _{P A0} are outputted alternately state or P ₀ and P _A1 is one of the states are alternately output.

Further, since the DC component of the output from the detecting means 20 is blocked by the capacitor 22, the output through the rectifying means 24 and the smoothing means 26 is reduced to the magnitude of the AC component as shown in FIG. The output signal is accordingly. Therefore, the reference voltage Vs is preset in the middle between the output _VA1 when the object 40 exists above the directivity range of the directional antenna 10 and the output _VA0 when the object 40 does not exist. Then, as shown in FIG. 3D, if the object 40 is present above, “L” is output from the comparing means 28, and if not, “H” is output. In this manner, a determination signal for determining whether or not the object 40 is located above the directivity range is output from the output of the comparing means 28.

Here, due to the change in the environmental temperature, the earth 14
The magnitude of the natural thermal noise radiated from the detector and the magnitude of the thermal noise generated by the apparatus itself change, and the powers P ₀ , P _A1 , P _A0 output from the detection means 20 change, but P ₀ and P signal corresponding to the magnitude of the alternating current component generated by switching the _A1 alternately, or P ₀ and the signal corresponding to the magnitude of the AC component results in a P _A0 is switched alternately, so that compared with the reference value Vs, the AC component The change in the thermal noise due to the change in the environmental temperature is offset in the signal according to the magnitude of the noise, and accurate discrimination is possible in the above embodiment.

If the change in the environmental temperature is ignored or the reference value Vs is appropriately changed according to the change in the environmental temperature, the switch means 12 is omitted, and the magnitude of the power output from the detection means 20 is reduced. The comparison value may be compared with the reference value Vs. The setting of the reference value Vs can be performed according to the estimation of T _A0 and T _A1 when designing the device. However, the reference value Vs is adjusted and set by actually operating the device itself at the installation location. Is also good.

FIG. 4 is a diagram showing another embodiment of the apparatus for detecting an object located above according to the present invention. In another embodiment shown in FIG. 4, the directional antenna 10 is arranged substantially horizontally, and a good conductor reflection plate 36 arranged obliquely upward at approximately 45 ° with respect to the ground 14 is arranged in front of the directional antenna 10. I have. The area of the good conductor reflection plate 36 is large enough to cover the directivity range of the directional antenna 10.

In such a configuration, the good conductor reflection plate 36
Of the object 4 above the good conductor reflection plate 36 even if the directional antenna 10 is not
The presence or absence of 0 can be determined. Therefore, the degree of freedom in designing the arrangement and the like of the directional antenna 10 is increased. It goes without saying that natural heat noise from the ground 14 is not directly incident on the directional antenna 10. In addition, it is a matter of course that natural heat noise from the ground 14 is reflected by the good conductor reflection plate 36 and does not enter the directional antenna 10.

[0022]

As described above, since the apparatus for detecting an object located above the present invention is constructed, the following special effects can be obtained.

According to the above-mentioned apparatus for detecting an object located above, a natural heat noise radiated from the ground is received by a directional antenna from a radio wave or the like reflected by an object located above the ground, and an output from the earth is detected. And the output of the non-reflection terminator having the same environmental temperature as above is alternately given to the amplifying means, and it is determined whether or not there is an object above the directivity range from the magnitude of the AC component. , The determination result does not become erroneous, the presence or absence of an object above can be accurately determined, and the reliability of the apparatus is improved accordingly. Further, the device itself does not require a means for emitting a radio wave, so that the device is simple, the size can be easily reduced, and the device can be manufactured at low cost. Since no radio waves are emitted, power consumption is low. Furthermore, since the device operates with small power, the life and reliability of the device itself can be improved. Furthermore, since radio waves are not emitted from the device itself, even if a plurality of the present devices are arranged at close positions, they do not interfere with each other and malfunction.
In addition, there is no need for legal approval and operation is extremely easy. Particularly, at an airfield or the like, a directional antenna is embedded and arranged in the ground of the route of the aircraft, and is suitable for determining the presence or absence of a ground body or the like on the route.

In the above-described apparatus for detecting an object located above, the directivity direction of the directional antenna is refracted by using the good conductor reflector, so that the degree of freedom in designing the arrangement of the directional antenna is improved. Is big.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram of an embodiment of a device for detecting an object located above according to the present invention.

FIG. 2 is a diagram illustrating an arrangement of a directional antenna.

FIG. 3 is a waveform chart in the circuit of FIG. 1;

FIG. 4 is a diagram showing another embodiment of the device for detecting an object located above the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 directional antenna 12 switch means 14 ground 16 non-reflection terminator 18 low noise amplifying means 20 detecting means 22 capacitor 24 rectifying means 26 smoothing means 28 comparing means 30 reference voltage means 32 switch control means 34 discriminating means 40 object

Continuation of front page (56) References JP-A-64-78181 (JP, A) JP-A-4-2985 (JP, A) JP-A-60-40974 (JP, A) JP-A-3-120487 (JP , A) Japanese Utility Model Hei 5-47879 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01S ⁷ /00-7/42 G01S 13/00-13/95 G01V 3/12

Claims (2)

(57) [Claims] 1. A directional antenna is arranged on the ground facing the sky, and natural heat noise radiated from the ground receives a reflected wave reflected by an object located above the directional antenna, and is received by the directional antenna. The output of the noise radio wave and the output of the non-reflection terminator at the same environmental temperature as the ground are alternately switched by the switch means and supplied to the amplifier means. By converting the signal into a signal corresponding to the magnitude and comparing the signal with a preset reference value by a comparing means, it is configured to determine the presence or absence of an object above the directional antenna. A device for detecting an object located above. 2. The apparatus for detecting an object located above according to claim 1, wherein a good conductor reflector is disposed obliquely upward.
An apparatus for detecting an object located above, wherein the directional antenna is arranged to face the good conductor reflection plate so that the antenna directivity reflected by the good conductor reflection plate faces the sky.