JP2517848B2 - Aircraft identification method and device using secondary radar - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an aircraft identification system by a secondary radar and its apparatus.

[Prior Art] A secondary radar (hereinafter referred to as SSR) currently used as an airport surveillance radar has an SSR station Tx installed near runways A and B as shown in FIG. There is. This SSR station
The Tx transmitting antenna emits a regular SSR interrogation signal with a narrow beam 50, and the transponders mounted on each of the multiple aircraft 51 and 52 flying within this beam 50 transmit interrogation signals respectively. The reception and decoding are performed and the corresponding response signals are transmitted.

The response signal from the transponder is normally received by the SSR station Tx at the same antenna as the transmission antenna and decoded to identify the aircraft 51, 52, and the response from the direction of the transmission antenna and the transmission time of the inquiry signal. From the time until the signal is received, the bearing and the distance of the aircraft 51, 52 having the transponder which responded are specified.

[Problems to be Solved by the Invention] With such a configuration, the response signals are transmitted from the transponders of all the aircrafts 51 and 52 flying in the beam 50.

Therefore, as shown in FIG. 8, at an airport provided with two parallel runways A and B that are close to each other, aircraft 51 and 52 approach each runway A and B at an adjacent distance. There is a case. In this case, SSR station Tx, aircraft 5
Since the response signals from 1 and 52 are received overlapping,
The received signal is garbled and cannot be identified.

On the other hand, the response signal from the transponder is transmitted after the specified delay time, but the response delay time has an error, so the distance accuracy is poor, and the current SSR has a runway A that is parallel to the airport. , It is not possible to obtain a monitoring function enough to monitor the aircraft 51, 52 near B.

[Means for Solving Problems] The present invention is directed to an SSR station Tx ₂ which issues a regular SSR interrogation signal for identifying a plurality of aircraft flying in a beam.
And the SSR station Tx ₁ that emits a suppression SSR interrogation signal for setting the response restriction area that suppresses the response of the transponder of one of multiple aircraft, and the SSR station Tx ₁ that fires before the regular SSR interrogation signal, are installed apart from each other. And at least SSR station T
The transmission point of x ₁ is installed so as to be located between two runways that are installed in parallel or between the extension lines of these two runways, passing through SSR station Tx ₁ and On the runway, set the response limit areas in the azimuth area in the positive and negative directions with respect to the center line, fly within the beam of the regular SSR interrogation signal, and approach both runways respectively. A plurality of aircraft in a garbled state can be identified by sequentially identifying a plurality of aircraft in flight.

Also, from the SSR station Tx ₁ , following the emission of the ▲ P ^' ₁ ▼ pulse from the sum pattern, the emission of the ▲ P ^' ₂ ▼ pulse from the composite pattern of this sum pattern and the difference pattern, and then the predetermined By issuing a regular SSR interrogation signal within the suppression time, a response limiting area is formed in the positive azimuth area of the SST station Tx ₁ , and following the emission of the ▲ P ^' ₁ ▼ pulse from the sum pattern, this After the ▲ P ^' ₂ ▼ pulse from the combined pattern of the sum pattern and the difference pattern with opposite polarities is emitted, a regular SSR inquiry signal is emitted within a predetermined suppression time, so that the SSR station Tx ₁ The response restricted area is formed in the azimuth area in the negative direction, and the response restricted area is formed by dividing the azimuth area in the positive direction and the negative direction of the SSR station Tx ₁ and the flight is made in this response restricted area. Suppresses the emission of response signals from operating aircraft and limits response In areas other than frequency, so that to identify the aircraft that and flying in the beam of normal SSR interrogation.

Furthermore, by receiving a response signal from the aircraft by SSR interrogation of regular emitted from SSR station Tx ₂ at the reception point R _X2 of SSR station T _x2, obtained by measuring the azimuth and distance of the aircraft Area Eγ and the reception points of SSR stations Tx ₁ and Tx ₂ respectively, measure the arrival time difference of the response signal from the aircraft due to the regular SSR interrogation signal, and measure the SSR stations Tx ₁ and SSR.
A station Tx ₂ measures the hyperbolic width E _t to the focus, the the hyperbolic width E _t and area Eγ is so as to measure the distance from the intersection area E that intersect, have improved range accuracy.

The reception point of the SSR station Tx ₁ which is installed at the focal point of the hyperbola showing the arrival time difference of the response signal from the aircraft R ₁ and SSR station T _x2
The receiving point F ₂ O of the SSR station T x ₁ is located so that the two areas of the two runways for which high distance accuracy is required are located between the receiving point R _{X2 of} By arranging _two , the distance accuracy of points where high distance accuracy is required, such as near the touchdown of the runway, is increased.

[Operation] Set the SSR station Tx ₁ emitting the suppression SSR interrogation signal to the normal S
The azimuth region between the positive and negative directions of SSR station Tx ₁ is arranged along the extension line between the aircrafts flying close to each other in the beam of SSR station Tx ₂ emitting the SR inquiry signal. The response limiting region for suppressing the emission of the response signal of the transponder is formed, and the emission of the response signal for one aircraft flying in the response limiting region is suppressed to identify the other aircraft.

Then, a response limited area is formed in the area where the other aircraft is flying to suppress the emission of the response signal and the response signal from the one aircraft is received and identified.

In addition, the area Eγ obtained by measuring the direction and the distance of the aircraft at the SSR station Tx ₂ which is emitting the regular SSR inquiry signal, and SS
The crossing region E where the hyperbolic width E _t obtained by measuring the arrival time difference of the response signal from the aircraft to the R station Tx ₁ and the SSR station Tx ₂ intersects is set to improve the distance accuracy.

The reception points of the SSR station Tx ₁ and the SSR station Tx ₂ are installed at the focal point of a hyperbola showing the arrival time difference of the response signal from the aircraft. Therefore, between the focal points and on the straight line connecting the focal points, an area where high distance accuracy is required, such as two touchdown points of two runways, is located.
The reception point of SSR station Tx ₁ is located.

[Embodiment] An embodiment of the present invention will be described in detail with reference to FIGS. 1 to 6.

FIG. 1 shows a principle diagram of a secondary radar system according to the present invention, in which two runways A and B are provided close to each other at an airport. At the midpoint between Runway A and Runway B, which are provided in parallel, SSR station Tx ₁ is installed,
SSR station Tx ₂ is located at a suitable distance from areas 1 and 2 which indicate the touchdown areas of runway A and runway B, respectively.
Is installed.

From the SSR station Tx ₁ , as shown in FIGS. 2 (a) and 2 (b), ▲ P ^′ ₁ ▼ pulse and ▲ P ^′ which are suppression SSR interrogation signals.
₂ ▼ Pulses are fired at time intervals of 2 μs.

Sum ▲ P _^'1 ▼ pulse having the characteristics of even function as shown in FIG. 3 (a) ~ (c), relative to the azimuth angle as seen from the SSR station Tx ₁ θ = 0 (Figure 4) Fired as pattern 3.

▲ P _^'2 ▼ pulse, the sum pattern 3 Figure 3 combined pattern 5 (FIG. 3 by synthesis and difference pattern 4 having the characteristics of an odd function with respect to the azimuth angle theta = 0 shown in (a) (b )) And a combined pattern 6 (third pattern) of the sum pattern 3 and the difference pattern 4 with opposite polarities.
(Shown in Figure (c)).

The SSR station Tx ₂ is similar to the current SSR transmitter, and as shown in FIGS. 2 (a) and 2 (b), the suppression SSR inquiry signal ▲ P
^' ₂ ▼ Suppression time τ (τ = 35μs ± 10μ
s) within the regular SSR interrogation signal P ₁ pulse, P ₂ pulse, P ₃
The pulses are fired with a narrow beam 7 at predetermined time intervals, and the received signals replied from the transponders of the aircraft are measured for azimuth and distance using monopulse side angle techniques.

In this embodiment, the reception point of both SSR station Tx ₁ and SSR station Tx ₂ is installed at the same location as the transmission point.

8 and 9 are aircraft that enter the runways A and B, respectively.
It is in the garbled state.

FIG. 5 shows a block diagram of a system according to the invention for identifying and measuring aircraft 8, 9 in the gable state, which system comprises SSR stations Tx ₁ and SS.
It is composed of an R station Tx ₂ and a central control unit 10 (hereinafter referred to as CPU 10).

SSR station Tx ₂ emits a regular SSR interrogation signal,
The identification code of the response signals from the aircrafts 8 and 9 is decoded. 11 is a monopulse receiver, 12 is an SSR transmitter, 13 is a transmission / reception switcher, and 14 is an antenna for both transmission and reception.

SSR station Tx ₁ is for setting the response limit area.
Is a signal generator for generating the ▲ P ^′ ₁ ▼ and ▲ P ^′ ₂ ▼ pulses of the suppressed SSR interrogation signal, and 16 is for adjusting the power ratio between the ▲ P ^′ ₁ ▼ and ▲ P ^′ ₂ ▼ pulses. , ▲ P
^´ ₁ ▼ When a pulse is emitted, only the sum pattern power distributor 17 is supplied with ▲ P ^´ ₁ ▼ pulse, and when a ▲ P ^′ ₂ ▼ pulse is emitted, the sum pattern power distributor 17 and the difference pattern power distributor To ▲ P ^′ ₂ ▼ Pulse distribution power regulator, 17 is a sum pattern power distributor for forming signals distributed by the power regulator 16 into the sum pattern 3, and 18 is a power regulator 16
A difference pattern power divider for forming the signal distributed by the difference pattern 4 into a difference pattern 4;
▲ P ^' ₂ ▼ from the polarity switch to switch the polarity of the pulse,
20 is the signal from the sum pattern power distributor 17 and the polarity switch 19
A synthesizer for synthesizing the signal from the difference pattern power divider 18 via the, 21 is a transmission / reception switch, 22 is an antenna for sequentially emitting the sum pattern 3 and the synthetic patterns 5, 6, and 23 is an aircraft 8, 9 SSR that receives the response signal from the transponder
The receiver, 24 is a code decoder for decoding the received response signal.

25 is a transmission time controller that controls the transmission time of the signal generator 15 and the SSR station Tx ₂ , 26 is a time difference measuring device that measures the arrival time difference between the response signals received by the SSR station Tx ₂ and the SSR station Tx ₁ , respectively.
27 is a code collator that collates the identification codes respectively identified by the SSR station Tx ₁ and the SSR station Tx _2, and 28 is a display that displays the time difference information of the time difference measuring device 26 and the information from the code collator 27. is there.

 Next, the operation will be described.

First, as a property of the current transponder mounted on the aircrafts 8 and 9, generally, as shown in FIG. 2 (a), the amplitude of the ▲ P ^' ₁ ▼ pulse of the suppression SSR interrogation signal is ▲
P ^'if ₂ ▼ 9 dB or more than the amplitude of the pulse large, the transponder has a reroute condition, ▲ ^P' ₂ ▼ after a pulse is received, P ₁ pulse normal SSR interrogation, P
_{When 2} pulses and P ₃ pulses are received, the response signal can be transmitted.

On the other hand, as shown in FIG. 2B, when the amplitude of the ▲ P ^' ₁ ▼ pulse is smaller than the amplitude of the ▲ P ^' ₂ ▼ pulse, the transponder is in a suppressed state, and ▲ P ^' ₂
▼ After the pulse is received, the specified suppression time τ (τ = 35μ
During s), the transmission of the response signal is restricted when the regular SSR interrogation signal is received.

Therefore, in the present invention, as shown in FIG. 4, by utilizing the above-mentioned property of the transponder, either one of the transponders of the aircrafts 8 and 9 approaching the parallel runways A and B in the garble state can be used. Honda sequentially sets the response restriction area in which the response signal cannot be transmitted, thereby preventing the occurrence of the garbled state and enabling the aircrafts 8 and 9 to be identified.

Hereinafter, this principle will be described in detail with reference to FIGS. 1 to 5.

At the SSR station Tx ₁ , the suppression SSR inquiry signal ▲ P ^' ₁ ▼
And the pulse and ▲ P _^'2 ▼ pulse is emitted. That is, CPU1
Under the control of the transmission time controller 25 of 0, the signal generator 15 generated the ▲ P ^' ₁ ▼ pulse of the control SSR inquiry signal for 2 μs.
Later, to generate the ▲ ^P _'2 ▼ pulse.

▲ P ^′ ₁ ▼ The pulse is transmitted to the antenna 22 via the power regulator 16, the sum pattern power distributor 17, the combiner 20, and the transmission / reception switcher 21.
Is fired as a Japanese pattern 3. Japanese pattern 3 is
As shown in FIGS. 3 (a) and 4, the azimuth angle θ
It has an even function characteristic for = 0 °.

▲ P _^'2 ▼ pulses, the power regulator 16 and distributed to the sum pattern power divider 17 and difference pattern power divider 18. Input to the differential pattern power distributor 18 ▲ P _^'2 ▼ pulses, through the sum pattern power divider 17 in the combiner 20 through the polarity switch 19 ▲ ^P' is combined with ₂ ▼ pulse.
The combined ▲ P _^'2 ▼ pulse from the antenna 22 through the duplexer 21, a combined pattern 5 shown in FIG. 3 (b), also, the sum pattern 3 and the polarity switching unit 19 It is fired as a combined pattern 6 shown in FIG. 3 (c) obtained by combining the reverse polarity pattern of the difference pattern 4 obtained by switching the polarities.

The difference pattern 4 has the characteristic of an odd function with respect to the azimuth angle θ = 0 °, as shown in FIGS. 3 (a) and 4. In addition, the ▲ P ^' ₁ ▼ pulse coverage of the suppression SSR interrogation signal is
While being adjusted by the power regulator 16, the power regulator 16 is adjusted also cover area of optimum power ratio and ▲ P _^'2 ▼ pulses the sum pattern 3 and difference pattern 4 in space.

From SSR station Tx _2, similarly to the SSR transmission apparatus working by SSR transmitter 12, P ₁ pulse normal SSR interrogation signal shown in FIG. 2, P ₂ pulse, P ₃ pulse the duplexer 13 A narrow beam 7 is emitted from the antenna 14 via the antenna 14.

Here, as for the regular SSR inquiry signal, under the control of the transmission time controller 25, the transponders mounted on the aircrafts 8 and 9 approaching the runways A and B received a ▲ P ^' ₂ ▼ pulse. After that, they are fired at time intervals such that the regular SSR inquiry signal arrives within the suppression time τ.

At this time, this time interval is determined to be a time interval other than the time interval of 8 μs or 21 μs so that the time interval of the ▲ P ^′ ₁ ▼ pulse and the P ₁ pulse is not confused as mode A or mode C. It

As shown in FIG. 4, it is assumed that aircraft 8 and 9 are approaching runways A and B, which are installed close to each other and in parallel, in a garbled state, respectively.

Therefore, first, a case where only the transponder of the aircraft 8 entering the runway A is identified in response to the regular SSR interrogation signal and the transponder of the aircraft 9 entering the runway B is limited in response will be described. .

As shown in FIGS. 3 (a) to (c), the SSR station Tx ₁ normally emits a ▲ P ^' ₁ ▼ pulse by the sum pattern 3, and the sum pattern 3 and the difference pattern 4 are combined. ▲ P _^'2 ▼ pulses from composite pattern 5 and 6 are is fired.

Here, SS installed between parallel runways A and B
The azimuth angle θ is defined as 0 at the center line S along the runways A and B at a point passing through the R station Tx ₁ .

Now, from the SSR station Tx ₁ , as shown in FIG. 3 (b), a ▲ P ^' ₁ ▼ pulse is emitted by the sum pattern 3, and the synthetic pattern 5 combining the sum pattern 3 and the difference pattern 4 P _^'2 ▼ pulse is emitted.

Therefore, in the region where the azimuth angle θ is positive (the region on the right side of the center line S in FIG. 4), the amplitude of the ▲ P ^' ₁ ▼ pulse (sum pattern 3) is the ▲ P ^' ₂ ▼ pulse (combined pattern 5). Since it is smaller than the amplitude, as shown in FIG. 3 (b), ▲ P
^' ₂ ▼ During the suppression time τ after receiving the pulse, the response limiting region where the response of the transponder is limited is set in the region where the azimuth angle θ is positive.

Therefore, the transponder mounted on the aircraft 9 entering the runway B cannot respond to the regular SSR interrogation signal.

On the other hand, a region in which the azimuth angle θ is negative (in FIG. 4, the center line S
In the region on the left side of FIG. 3B, as shown in FIG. 3B, the amplitude of the pulse (sum pattern 3) of ▲ P ^' ₁ ▼ P
^′ ₂ ▼ The amplitude of the pulse (combined pattern 5) is small, and in particular, as shown in FIG. 2 (a), in the portion smaller than 9 dB, the normal SSR interrogation signal reached during the suppression time τ is The transponder mounted on the aircraft 8 is ready to respond.

Therefore, the transponder mounted on the aircraft 8 entering the runway A can reliably respond to the regular SSR interrogation signal.

Therefore, the suppression SSR interrogation signal ▲ P ^' ₁ ▼ pulse, ▲ P ^'
₂ ▼ When the transponder of the aircraft 8 responds to the regular SSR inquiry signals P ₁ , P ₂ , and P ₃ pulses following the pulse, the antenna 14 receives the response signal from the aircraft 8 that reaches the SSR station Tx _2. Then, the signal passes through the transmission / reception switch 13 and part of it is input to the monopulse receiver 11, and the azimuth angle θ at the SSR station Tx ₂
And the distance are measured to obtain the area Eγ, the identification code of the aircraft 8 is decoded, and the code collator 27 of the CPU 10
And the display 28 is input.

Another part of the signal that has passed through the transmission / reception switching device 13 is input to the time difference measuring device 26 of the CPU 10.

On the other hand, the response signal from the aircraft 8 reaching the SSR station Tx ₁ is received by the antenna 22, passes through the duplexer 21, and passes through the SSR.
The code is input to the receiver 23, and a part of the output is decoded by the code decoder 24 to decode the identification code of the aircraft 8.
Is input to Some of the other output from the SSR receiver 23 is C
It is input to the time difference measuring device 26 of PU10, the SSR station Tx _{2 is} received,
The arrival time difference from the measured response signal from the aircraft 8 is measured. From this arrival time difference, as shown in FIG.
It is possible to obtain a hyperbolic width E _t with an error width that focuses on the SSR station Tx ₁ and the SSTT station Tx ₂ .

A part of the signal input to the code collator 27 is collated with the identification code of the aircraft 8 decoded by the monopulse receiver 11 of the SSR station Tx ₂ . On the display unit 28, the azimuth and distance information decoded by the monopulse receiver 11, the time information obtained by the time difference measuring unit 26, and the information from the code matching unit 27 are processed and displayed.

Therefore, the aircraft 8 is in the area Eγ obtained by the SSR station Tx _2.
The azimuth and the distance are measured as being detected in the intersection area E where the and the hyperbolic width E _t intersect.

This is because the aircraft 8 can determine the distance within the narrow intersection area E, while the distance has been determined in the area Eγ which was conventionally obtained by the SSR station Tx _2. Therefore, the distance accuracy is remarkably improved. .

A case will now be described in which only the transponders of aircraft 9 entering runway B are identified in response to a legitimate SSR interrogation signal, and the transponders of aircraft 8 entering runway A have limited response.

Now, from the SSR station Tx ₁ , as shown in FIG. 3 (c), a ▲ P ^′ ₁ ▼ pulse is emitted by the sum pattern 3, and further, it is shown in the sum pattern 3 and FIG. 3 (a). the composite pattern 6 is obtained by combining the reverse polarity pattern and difference pattern 4 are ▲ P _^'2 ▼ pulse is fired.

Therefore, in the region where the azimuth angle θ is negative (the region on the left side of the center line S in FIG. 4), the amplitude of the ▲ P ^′ ₂ ▼ pulse (combined pattern 6) is the ▲ P ^′ ₁ ▼ pulse (sum pattern 3). Since the amplitude is larger than the amplitude, as shown in FIG.
^' ₂ ▼ During the suppression time τ after receiving the pulse, the response limiting region where the response of the SSR transponder is limited is set in the region where the azimuth θ is negative. Therefore, the transponder mounted on the aircraft 8 entering the runway A cannot respond to the regular SSR interrogation signal.

On the other hand, a region in which the azimuth angle θ is positive (center line S in FIG. 4)
In the area on the right side of), as shown in FIG.
^The amplitude of the ▲ P ^' ₂ ▼ pulse (synthesis pattern 6) is smaller than that of the ^´ ₁ ▼ pulse (sum pattern 3), and in particular, as shown in FIG. The transponder of the aircraft 9 is ready to respond to the regular SSR inquiry signal that has arrived during the suppression time τ. Therefore, the transponder mounted on the aircraft 9 entering the runway B can reliably respond to the regular SSR interrogation signal.

Therefore, in the same manner as described above, the regular SS following the suppression SSR interrogation signal ▲ P ^' ₁ ▼ pulse and ▲ P ^' ₂ ▼ pulse
R interrogation signal P ₁ pulses, P ₂ pulse, if the transponder of the aircraft 9 to P ₃ pulse has responded, the response signal from the aircraft 9 has reached the SSR station Tx ₂ includes azimuth and distance measurement in the SSR station Tx ₂ Then, a region (not shown) similar to the above regarding the aircraft 9 is obtained.

Further, similarly, the arrival time difference between the response signals received from the aircraft 9 at the SSR station Tx ₁ and the SSR station Tx ₂ is measured. From this arrival time difference, as shown in Fig. 1, SSR
Aircraft 9 with a margin of error focusing on station Tx ₁ and SST station Tx ₂
A hyperbolic width (not shown) for can be obtained.

Therefore, the aircraft 9 entering the runway B is detected as being present in the intersection area (not shown) where the area obtained by the SSR station Tx ₂ and the hyperbolic width intersect, and the azimuth and distance are measured. It

In this embodiment, the SSR station Tx ₁ is installed between the runways A and B, and the azimuth angle θ is set to 0 at the center line S, but the present invention is not limited to this. If the SSR station Tx ₁ exists on the extension line between aircrafts flying in close proximity to each other, then the azimuth angle θ =
When it is set to 0, the same effect as that of the above embodiment can be obtained.

Another embodiment of the present invention will be described with reference to FIGS. 1, 6, and 7.

In the first embodiment, an SSR station that emits a suppressed SSR interrogation signal
Tx ₁ is for both transmission and reception, and the case where the transmission point and the reception point are installed at the same location was explained.

Therefore, as shown in FIG. 1, since the response signal from the aircraft 8 is received at the two receiving points, the SSR station Tx ₁
And SSR station Tx ₂ are installed at the focal points of the hyperbola obtained by measuring the arrival time difference. Therefore, the maximum distance accuracy can be obtained in the area 1 on the runway A located between the focal points. Sogo SSR so that Area 1 is located at the touchdown point on Runway A
If the station Tx ₁ and the SSR station Tx ₂ are installed, the maximum distance accuracy can be obtained in this area 1.

On the other hand, touchdown area 2 on runway B
The distance accuracy at will be poor.

Therefore, in this embodiment, as shown in FIG.
At least only the transmission point ▲ Tx ^' ₁ ▼ of x ₁ is installed between the runways A and B.

On the other hand, since each focal point of the hyperbola showing the arrival time difference of the response signal and the reception point R _X1 of SSR station Tx ₁ and reception point R _X2 of SSR station Tx ₂ is installed installed, and Area 1 and Area 2 is SSR
The reception point Rx ₁ is arranged between the reception point Rx ₁ of the station T _X1 and the reception point R _X2 of the SSR station Tx ₂ and on the straight line connecting these two points (focus points).

As shown in FIG. 7, from the transmission point ▲ Tx ^′ ₁ ▼ of the SSR station Tx ₁ , the suppression SSR inquiry signal is transmitted by the sum pattern 3, the combination patterns 5 and 6 similar to the first embodiment, and the transmission-only antenna. Fired from 30.

On the other hand, the response signals from the aircrafts 8 and 9 are received by the reception-only antenna 31 at the reception point Rx ₁ , and the SSR receiver 23
A part of the signal from the signal is input to the code decoder 24 to decode the identification code of the aircraft, and is input to the code collator 27 in the same manner as described in the first embodiment. The other part of the signal from the SSR receiver 23 is input to the time difference measuring device 26 of the CPU 10 and the time difference with the received signal from the SSR station Tx ₂ is measured, the same as described in the first embodiment. Then, the intersection area E is determined.

In this way, the reception point of the SSR station Tx ₁ installed at the focal point of the hyperbola showing the difference in arrival time of the response signal from the transponder.
On a straight line connecting the R _X1 and receiving point R _X2 of SSR station Tx _2, by arranging the reception point Rx ₁ and R _X2 so that areas 1 and 2 where high distance accuracy is required to position the touch At a point where high distance accuracy is required, such as in the vicinity of down, sufficient distance accuracy can be obtained as compared with the conventional point.

[Advantage of the Invention] The present invention is an SSR station Tx ₂ which issues a regular SSR interrogation signal for identifying a plurality of aircraft flying in a beam.
And suppression for setting a response limited area that suppresses the firing of the response signal of the transponder of any of the multiple aircraft
SSR station T that fires the SSR interrogation signal before the regular SSR interrogation signal
x ₁ and x should be placed away from each other and at least SS
The transmission point of R station Tx ₁ is installed so as to be located between two runways that are installed in parallel or between the extension lines of these two runways, and passes through SSR station Tx ₁ and 2 On the runway of the book, the response restriction area is set sequentially in the azimuth area in the positive and negative directions with the center line as the reference, so that the response signal from the aircraft flying in the response restriction area is suppressed. , It is possible to identify multiple aircraft that are flying in the beam of the legitimate SSR interrogation signal in areas other than the response restriction area and are approaching both runways respectively, and eliminate the gable state. I can.

Further, the area Eγ obtained by measuring the bearing and the distance of this aircraft by the response signal from the aircraft by the regular SSR interrogation signal emitted from the SSR station Tx ₂ and the SSR stations Tx ₁ and SS.
At each receiving point with R station Tx ₂ , measure the arrival time difference of the response signal from the aircraft due to the regular SSR interrogation signal.
A SSR station Tx ₁ and SSR station Tx ₂ measures the hyperbolic width E _t to focus, intersection region E where the the hyperbolic width E _t and area Eγ intersect
Since the distance is measured from, the sufficient distance accuracy can be obtained as compared with the conventional one.

In addition, SSR station Tx ₁ , SSR station Tx ₂ installed at the airport,
The closer the aircraft is to the airport, the higher the distance accuracy becomes. Therefore, it is most suitable as an airport surveillance radar, and it is economical because two transmitting and receiving stations are required.

In addition, the receiving point R _X1 of the SSR station Tx ₁ installed at the focal point of the hyperbola that indicates the arrival time difference of the response signal from the aircraft and the SSR station Tx
_Two runways that require high distance accuracy between the _two receiving points R _X2 and the receiving point and on the straight line connecting the focal points.
SSR station Tx ₁ receiving point R _X1 and SSR so that two areas are located
By arranging the reception point R _X2 of the station T _x2 , it is possible to improve the distance accuracy of a point where high distance accuracy is required, such as near the touchdown of the runway.

[Brief description of drawings]

1 to 5 show a first embodiment of the present invention, in which FIG. 1 is a principle diagram, FIG. 2 is a pulse waveform diagram, and FIG. 3 is a suppression SSR interrogation signal emission pattern. Figures and 4 show SSR
FIG. 5 is a diagram showing a positional relationship between the station Tx ₁ and the SSR station Tx _2, and FIG. 5 is a block diagram of this system. 6 to 7 show a second embodiment of the present invention, and FIG. 6 shows the positional relationship between the transmission point ▲ Tx ^' ₁ ▼ of the SSR station and the SSR station Tx ₂ and the reception point Rx _1. FIG. 7, FIG. 7 is a block diagram, and FIG. 8 is a diagram showing a conventional example. Tx ₁ , Tx ₂ ...... SSR station E γ area E _t …… hyperbolic width E …… intersection area 1, 2 …… area 3 …… sum pattern 4 …… difference pattern 5, 6 …… composite pattern 7 …… Beam 8, 9 ... Aircraft 10 ... CPU 11 ... Monopulse receiver 12 ... SSR transmitter 13, 21 ... Transmission / reception switch 14, 22 ... Antenna 15 ... Signal generator 16 ... Power regulator 17 …… Sum pattern power distributor 18 …… Difference pattern power distributor 19 …… Polarity switch 20 …… Combiner 23 …… SSR receiver 24 …… Code decoder 25 …… Transmission time controller 26 …… Time difference measurement Instrument 27 …… Code collator 28 …… Display

Claims (5)

(57) [Claims] 1. An SSR station Tx which emits a regular SSR interrogation signal for identifying a plurality of aircraft flying in a beam.
₂ and the SSR station Tx ₁ that emits a suppression SSR interrogation signal for setting a response control area for suppressing the response of the transponder of one of the plurality of aircrafts before the regular SSR interrogation signal.
The SSR station Tx ₁ and the SSR station Tx ₂ are installed apart from each other, and the transmission point of the SSR station Tx ₁ is between two runways installed in parallel or between the two runways. It is installed so as to be located between the extension lines of the two runways, passes through the SSR station Tx _1, and is located in the direction angle region in the positive direction and the negative direction with reference to the center line along the two runways. By a secondary radar characterized by sequentially setting response signal restriction areas, flying in the beam of the regular SSR interrogation signal, and sequentially identifying a plurality of aircraft approaching each of the two runways How to identify an aircraft. 2. The suppressed SSR interrogation signal emitted from the SSR station Tx ₁ is composed of a ▲ P ^' ₁ ▼ pulse and a ▲ P ^' ₂ ▼ pulse,
Following the emission of the ▲ P ^' ₁ ▼ pulse from the Japanese pattern,
After emitting the ▲ P ^' ₂ pulse from the combined pattern of the sum pattern and the difference pattern, the normal SSR interrogation signal is emitted within a predetermined suppression time, whereby the SSR station Tx
_A response limiting region is formed in the azimuth region in the positive direction of ₁ , and the combined pattern of the sum pattern and the pattern in which the difference pattern has the opposite polarity is generated following the emission of the ▲ P ^' ₁ ▼ pulse from the sum pattern. By emitting the ▲ P ^′ ₂ pulse from the SSR station Tx _{1 and then} issuing a regular SSR interrogation signal within a predetermined suppression time, the response limiting area is formed in the negative azimuth area of the SSR station Tx _1. The method for identifying an aircraft by the secondary radar according to claim 1, wherein: 3. An area Eγ for measuring the azimuth and distance of the aircraft by a response signal from the aircraft based on a regular SSR interrogation signal emitted from the SSR station Tx ₂ , an SSR station Tx ₁ and an SSR station Tx ₂ . At each reception point of, the difference in arrival time of the response signal from the aircraft due to the regular SSR interrogation signal is measured, and the hyperbolic width E _t focused on the SSR station Tx ₁ and SSR station Tx ₂ is measured. E _t and the region Eγ and the intersection area E intersecting
The method for identifying an aircraft by the secondary radar according to claim 1 or 2, wherein the distance of the aircraft is measured. 4. A reception point of the SSR station Tx ₁ which is installed at the focal point of the hyperbola showing the arrival time difference of the response signal from the aircraft R _X1 and S
The SSR station Tx ₁ is positioned so that two areas of two runways for which high accuracy is required are located between the receiving point R _X2 of the SR station Tx ₂ and on the straight line connecting the focal points. 4. The method for identifying an aircraft by the secondary radar according to claim 3, wherein a reception point R _X1 of the SSR station and a reception point R _X2 of the SSR station Tx ₂ are arranged. 5. A normal SSR interrogation signal is emitted, and
An SSR station Tx ₂ for decoding the identification code of the response signal, a signal generator for generating the suppressed SSR interrogation signal ▲ P ^' ₁ ▼ pulse and ▲ P ^' ₂ ▼ pulse, and the ▲ P ^' ₂ ▼ pulse for the sum pattern A power regulator for distributing to the power distributor and the difference pattern power distributor;
^′ ₂ ▼ A polarity switcher that switches the polarity of the pulse, a combiner that combines the signal from the sum pattern power distributor and the signal from the difference pattern power distributor via the polarity switcher, and a sum pattern and combiner An SSR station Tx ₁ having an antenna for sequentially emitting patterns and a code decoder for decoding the received response signal, a transmission time controller for controlling the transmission time of the signal generator and the SSR station Tx ₂ , collates the time difference measuring device for measuring the arrival time difference of the response signals received respectively by the SSR station Tx ₂ and the SSR station Tx _1, the identification code identified respectively by the the SSR station Tx ₁ and the SSR station Tx ₂ An aircraft identification device using a secondary radar, comprising: a code collator; and a central processing unit having a display for displaying time difference information of the time difference measuring device and information from the code collator.