JPH07209404A - Target position detection method - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] When the target is out of the line of sight from the receiver, the position of the target is detected by the received signal of the receiver. [Structure] A target 10 that emits radio waves, a receiver 20 that finally receives the emission signal of the target and measures the propagation delay time of the received signal, and the target 10 and the receiver 20. A plurality of transponders 1, 2 and 3 as repeaters for receiving the radio wave emitted from the target 10 at any two or more line-of-sight positions between them and transmitting it to the one receiver 20. The relative delay time difference Δt _12, Δt ₂₃ between the three reception signals received by the receiver 20 from the radio waves transmitted from each of the repeater transponders 1, 2, 3 is measured, and the receiver 20 and each repeater transponder are measured. The receiver 20 knows the position of the target 10 by performing corrections based on the distances d ₀₁ , d ₀₂ , and d ₀₃ from ₁ , 2, and 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a target position detecting system for detecting the position of a target that emits radio waves by a reception signal of a receiver that receives the emitted radio waves at one place, and particularly to the target position detection system. Relates to a target position locating method when the target is out of the line of sight from the receiver.

[0002]

2. Description of the Related Art A conventional target position detection method generally uses a target T when a position of a target T that emits a radio wave is detected by a reception signal of a receiver R at one place as shown in FIG.
Was measured only in the case where there was no obstacle on the way from the receiver R and only the direction of the target T was measured as the direction in which the reception level was the highest. To detect the position including not only the direction of the target but also the distance, although not shown in the figure, generally, the radio waves transmitted from the target T are received at two or more positions where the target is in sight. A receiver having a measurement function for measuring the delay time difference of received signals is required. Therefore, only when the target is line-of-sight, a receiver having a measuring function is required at two or more locations, and the cost is high both in terms of hardware and labor.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a radio wave target when the target to emit the radio wave is out of sight as seen from a receiver that receives and measures the emitted radio wave. An object of the present invention is to provide a low-cost target position detection method capable of measuring not only the direction of the target but also the position including the distance by the received signal of the receiver at the location.

[0004]

As shown in the principle diagram of FIG. 1, the basic configuration of the present invention for achieving this goal is to finally send a target (10) that emits a radio wave and a launch signal of the target. A receiver that can detect the delay time of the received signal at one location (2
0) and arbitrary plural positions between the target (10) and the receiver (20) (direct distances d _01, d _02, d ₀₃ to the receiver 20 and mutual distances d _12, d).
₂₃ is known), and a plurality of transponders (1, 2, 3) as repeaters that simply receive the radio wave emitted from the target (10) and transmit it to the receiver (20). The radio waves transmitted from the repeater transponders (1, 2, 3) are sent to the receiver (2
0) measured the relative delay time difference (Δt _12, Δt ₂₃ ) between the _three received signals (s _1, s _2, s ₃ ), and measured the respective delay time differences (Δt _12, Δt ₂₃ ). by performing necessary correction due to the distance of the receiver (20) and each repeater transponders _{(1,2,3) (d 01, d} 02, d 03) with respect to _23), the position of the target (10) Is configured so that it can be known by the receiver (20) at one place.

[0005]

In the present invention, the radio waves transmitted from the repeater transponders (1, 2, 3 ─) provided at two or more arbitrary positions between the target (10) and the receiver (20) at one place are transmitted. One receiver
(20) receives and obtains a plurality of received signals s _1, s _2, s ₃ . Then, the relative delay time difference (Δt _12, Δt ₂₃ ) between any two received signals among the plurality of received signals s _{1 ,} s _2, s ₃ is measured. Then, for each measured delay time difference (Δt _12, Δt ₂₃ ), the distance (d ₀₁ , d ₀₂ , d ₀₃ ) between the receiver (20) and each repeater transponder (1,2,3) is necessary. By performing such correction, the position of the target (10) viewed from the receiver (20) is represented by two hyperbolas in which the respective delay time differences (Δt ₁₂ ′, Δt ₂₃ ′) after correction are constant. It can be known as the intersection of groups P1 and P2.

[0006]

FIG. 2 is an explanatory view of a target position detecting system according to an embodiment of the present invention, wherein three transponders A, 3 are provided as repeater transponders 1, 2, 3 provided at two or more line-of-sight positions. It is explanatory drawing of the method of calculating | requiring the position of the target (10) T at the time of providing B and C with one receiver (20) R.
First, the arrival time difference ΔTab from the target T in the two transponders A and B is obtained. The time Ttar until the emission signal from the target T reaches the receiver R via the transponder A is the time Tta from the target T to the transponder A.
And the time from the transponder A to the receiver R, Tar.
Ttar = Tta + Tar. Similarly, the time Ttbr until the emission signal from the target T reaches the receiver R via the transponder B is the time Ttb from the target T to the transponder B and the time Tbr from the transponder B to the receiver R.
And Ttbr = Ttb + Tbr. The time difference ΔTab ′ of the signal from the target T at the receiver R is based on A,
ΔTab '= Ttbr-Ttar = (Ttb + Tbr)-(Tta + Tar) = (Ttb-Tta) + (Tbr-Tar), where (Tbr-Tar) is the transponder A, B
And the position of the receiver R is known when it is selected. Time difference Δ between signals from target T in transponders A and B
Tab is obtained as ΔTab = Ttb−Tta = ΔTab ′ − (Tbr−Tar), and (Tbr−Tar) is known. Therefore, Δ
Draw a hyperbola P1 where Tab is a constant locus.

Similarly, the arrival time difference ΔTbc from the target T in the transponders B and C is obtained, and a hyperbola P2 having a constant ΔTbc locus is drawn. Finally, the position of the target T is obtained from the intersection of the hyperbola P1 and the hyperbola P2. Figure 2
In the explanatory view of the above embodiment, the hyperbola P1 is ΔTab = -ΔT1 _{, the} hyperbola P2 is ΔTbc = 0, and the position of the target T is obtained as the intersection thereof.

The plurality of repeater transponders (1, 2, 3), which are not shown in the figure, convert the frequency of the received signal, which is the radio wave emitted from the target (10), into another frequency. It can be configured as a frequency conversion type repeater for transmitting to the one receiver (20) (Claim 2),
In that case, the radio wave from the target (10) and the radio wave from the repeater transponder (1, 2, 3) can be easily separated, and the detection error can be reduced. In addition, the plurality of repeater transponders (1, 2, 3) simply reflect radio waves emitted from the target (10) and a part of them is transmitted to the one receiver (20). It can be configured as a passive repeater (Claim 3), and in that case, a power supply is not required, so construction and maintenance costs are reduced. Also, as shown in FIG.
Between the plurality of repeater transponders (1, 2, 3) and one receiver (20), with an optical fiber cable (30) for converting an electric signal into an optical signal and converting the optical signal into an electric signal. Connection can be made (claim 4), and in that case, interference from external radio waves can be reduced.

[0009]

As described above, according to the present invention, it is possible to easily detect the position of a distant target outside the line of sight with one receiver.

[Brief description of drawings]

FIG. 1 is a principle diagram showing a basic configuration of a target position detection method of the present invention.

FIG. 2 is an explanatory diagram of a target position detection method according to an embodiment of the present invention.

FIG. 3 is a configuration diagram of a target position detection system of an embodiment corresponding to claim 4 of the present invention.

FIG. 4 is a block diagram of a conventional target position detection method.

[Explanation of symbols]

1,2,3 are repeater transponders A, B, C, 10 is a target T, 20 is a receiver R, and 30 is an optical fiber cable.

Claims (4)

[Claims] 1. A target (10) for emitting a radio wave, a receiver (20) for finally receiving a launch signal of the target and measuring a propagation delay time of the received signal, and the target (10). 10) and the receiver
A plurality of transponders (1, 2) as repeaters for receiving the radio wave emitted from the target (10) at any two or more line-of-sight positions between (20) and transmitting it to the one receiver (20). 2,3) and the plurality of repeater transponders (1,2,3)
Relative delay time difference (Δt _12, Δt ₂₃ ) between the three received signals received by the one receiver (20) from each transmitted radio wave from
And the measured delay time difference (Δt _12, Δt ₂₃ ).
For the receiver (20) and each repeater transponder (1, 2,
A target characterized by knowing the position of the target (10) by the receiver (20) at the one location by performing necessary corrections based on the distance (d ₀₁ , d ₀₂ , d ₀₃ ) from the ₃ ) Location detection method. 2. The plurality of repeater transponders.
(1,2,3) is a frequency conversion type repeater that converts the frequency of the received signal received from the radio wave emitted from the target (10) to another frequency and transmits it to the one receiver (20). The target position detecting method according to claim 1, wherein 3. The plurality of repeater transponders.
(1,2,3) is a passive type repeater in which a radio wave emitted from the target (10) is reflected and a part of the radio wave is transmitted toward the one receiver (20). The target position detection method according to claim 1. 4. The plurality of repeater transponders.
The (1,2,3) and one receiver (20) are connected by an optical fiber cable (30) for converting an electric signal into an optical signal and converting an optical signal into an electric signal. The target position detection method according to claim 1.