DE3109125A1 - AIRPORT MONITORING DEVICE - Google Patents

Description

Patent attorney -

Dipl.-Phys. Leo Thul Mi _{Λ Λ} _ _

Short Street 8 31 09 125

7000 Stuttgart 30

G. Höfgen - P.Sothcott H.L. Cohrs 30-15-3

INTERNATIONAL STANDARD ELECTRIC CORPORATION, NEW YORK

Monitoring device for airports

The invention is based on a monitoring device as indicated in the preamble of claim 1. Such a monitoring device is from DE-OS 29 34 844 known.

In a secondary radar system used in aircraft, the response signal can be used for data transmission (e.g. for the coded representation of the identity of the aircraft). With the ICAO secondary radar surveillance system (SSR), the ground stations emit pulse pairs that are 8 / us apart in a certain mode. the The carrier frequency of the pulses is 1030 MHz. The aircraft transponder responds to an interrogation signal with a response signal, which is a pulse telegram. The distance between the frame pulses of the pulse telegram is approx. 20 / us. Of the The code for the aircraft is given by the spacing of the pulses within the two frame pulses. The ground station, which receives the response signal, contains a normal radar receiver and a decoder that receives the pulse telegram decoded.

To avoid the emission of response signals that respond to interrogation signals that are emitted via side lobes, will be given by the ground station £ in additional Pulse (known as P2 pulse) is emitted, which is timed between the P1 and P3 pulses. This P2 pulse is weaker than the P1 or P3 pulses, each

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but stronger than the signals that are emitted via side lobes. The P2 pulse is radiated all around. Through this one achieves that in the direction of the main lobe there is a relatively weak P2 pulse between the P1 and P3 pulses while in all other directions a relatively strong P2 pulse is obtained between the weak ones Receives pulses P1 and P3. The transponder on board the aircraft only responds to the stronger P1 and PS pulses. Synchronous key confusion can arise when the resolution between two neighboring Aiming is very small.

This problem is particularly severe when the system is used to identify aircraft will. There it is necessary to limit the P1-P3 pulse train to a small area or block to be monitored, in which there is usually only one target. In the system known from DE-OS 29 34 844 (compared to the normal main radar system) signals of very low power emitted by radar devices, which are arranged at equal intervals along the taxiway to be monitored and which are above each other Cables are connected. The radiation diagram of a radar device has a relatively large opening in the azimuth plane (e.g. + ^ 80) and is on the center line of the respective Taxiway directed, creating a fan-shaped surveillance sector is formed. These radars are activated in turn via a cable and each radar determines whether there is a vehicle in its surveillance sector is present or not. If a secondary radar transponder is present, the identity of the vehicle is also determined. This information is passed over the cable to the central monitoring device and the information is displayed there. The central monitoring facility is usually located in the control tower. In practice

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two such radar chains are used, with one radar chain being provided on each side of the taxiway. In such a system, two sets of radars are provided, each arranged opposite one another are. This creates pairs of devices. One of the pair's radars is an interrogator which, if it is activated, a 0.8 + _ 0.1 / us pulse P1 at a carrier frequency of 1030 +0.2 MHz radiates. The other radar of a pair receives this P1 pulse and emits another pulse, the P3 pulse, with the same frequency. Because of the existing routes and the delays in the second radar unit . a receiver on the center line of the taxiway receives a "standard P1-P3 pulse". In response to one such A transponder on board an aircraft replies to its code on the frequency 1090 + 3 MHz, 3 + 0.5 / us after the P3 pulse. The pulse telegram has a length of 20.75 yus. The answering station receives the response signal and forwards it via the cable to the central evaluation device. The individual radars can be activated according to a certain pattern (or individually if required).

The above system has some drawbacks. One of them is that the receivers can pick up false signals and thus emit unwanted response signals. It is also difficult to emit the individual pulses in such a way that they in the middle of the taxiway with the correct amplitudes. ■

With the new monitoring device, which in the claims 1 and 3, these disadvantages are eliminated. Beneficial Further developments are contained in the respective subclaims.

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There is a surveillance sector in the new airport surveillance system part of the path to be monitored, e.g. the runway. Radar sensors emit P1-PS pulse pairs and the P2 pulses. The P2 pulses are arranged between the P3 and P1 pulses The P2 impulses or the P1, P3 impulses have different power and different radiation patterns radiated. The powers and the radiation patterns are chosen so that the PI and P3 pulses from the receiver on board an aircraft in the respective monitoring sector with a signal amplitude greater than the pulse P2 can be received. The minimum value for the difference between the signal strengths is chosen so that the recipient recognizes an SSR query. This condition is only fulfilled in the respective surveillance sector The response signals emitted by the aircraft transponders are used in an embodiment of the new airport surveillance system received from a central facility. In this case, the response signals do not have to be over the lines are forwarded to the control center and the connections between the individual radar sensors exist in in this case from a "facility arrangement".

According to the teaching of claim 4, it is also possible in a surveillance sector to recognize targets that do not have an SSR transponder.

■ Since the response signals emitted by the aircraft have a relatively high power, it is relatively easy to built receiver can be used. The antenna gain of a receiving antenna does not have to be very large. A Receiver consists of little more than a capacity-matched one Diode detector. A simple amplifier is controlled with the output signal of such a receiver

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and the amplified output signal (the transponder response) is forwarded to the control center. The recipient can be constructed in such a way that it does not process pulses whose amplitude is below a certain threshold value. This prevents pulses associated with SSR response signals from remote plug-in witnesses from being received will. It is also possible to use square detectors for the detector circuit of the receiver To use characteristic curves; in this case the sensitivity drops quickly.

In order not to have any difficulties because of the threshold values, it is advantageous to use P2 pulses for the area that is not to be illuminated with P1 and P3 pulses "to illuminate". Care is taken to ensure that the surveillance sector is not irradiated with P2 pulses as far as possible will. However, a certain overlap of these areas cannot be avoided. In an advantageous manner an auxiliary transmitter is provided at one end of the runway or at other taxiways, which also has a receiver to receive the P1 pulse and the P2 pulses radiates. The P2 pulses are emitted 2 / us after receipt of a P1 pulse in such a way that outside of the monitoring sectors, the P2 pulses have a greater amplitude than the P1, P3 pulses. The correct one Relationship between the P1 and P2 pulses is obtained along the line between the two transmitters, however also outside of this line the relationship is still such that P1 and P3 pulses outside the monitoring sector are not used Triggering a response signal.

Instead of emitting the P2 pulse after receiving a P1; pulse, it is also possible to trigger the transmitter via cables or radio links in such a way that it sends the P2 pulses emits at the right times. By

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Appropriate emission of the P2 impulses, it is also possible suppress unwanted responses from nearby radars. You can proceed as follows: The "P2 pulse transmitter" emits two impulses. The first P2 pulse becomes 2 / us after its own P1 signal emitted to suppress P1-P3 radiation in reverse direction. The second signal is emitted a time T (less than 2 / us) after the point in time to which the P1-P3 pulses emitted by the neighboring radar set the far end of the taxiway

■ range. T is chosen so that the prescribed time relationships must be adhered to for complete suppression.

The activation of the individual interrogation devices can be done in a relatively simple manner. The individual query devices are addressed and addressed in a similar way as it is done with a paging system. the Addressing can be done in blocks or according to a certain pattern or in some other way. In the main office you can define how often a single query device should be activated in succession. For this the necessary codes are sent via cable or radio to the respective interrogation devices. Every broadcaster has a decoder and is passive until it receives its own address code. Only then does he shine the prescribed Transmission pulses. These are, depending on the code,

■ with which the interrogation device is addressed, the P1-PS-impulse or the P2-impulse. '.

The invention is explained in more detail with reference to the drawings, for example. E $ shows:

1 shows the arrangement for a first exemplary embodiment from several query stations along

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a runway and the polar diagrams assigned to them,

2 shows a schematic representation of an interrogation station,

Fig. 3 polar diagrams for the from an interrogation station according to Fig. 3 emitted signals,

4 shows the arrangement of the interrogation stations and the associated ones for a second exemplary embodiment Polar diagrams,

FIG. 5 shows a schematic representation of an interrogation station according to FIG. 4,

6 shows a perspective illustration of an interrogation station, and

7 shows the arrangement of the interrogation stations and the associated polar diagrams for another

Execution example1.

As can be seen from FIG. 1, the individual query stations 1, 2, 3 are on opposite sides arranged a taxiway to be monitored. Every

2Q questioner is assigned such a polar diagram that a number of adjacent and slightly overlapping surveillance sectors arise on the taxiway. from Seen from the runway, a surveillance sector is triangular. The polar diagrams shown in FIG. 1 are not the complete and correct polar diagrams for the individual interrogation stations but they have been simplified to the extent that the monitoring sectors, which are controlled by the individual polar diagrams are formed, are easily recognizable.

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In Fig. 2 is an interrogation station for a monitoring device shown in FIG. As in FIG. 1, no line is shown here either, with which the individual query stations are connected to the control center. The interrogation station contains a transmitter 10, which emits the P1-P3 pulse pairs. The generation of the pulse pairs is controlled by a pulse generator 11. This pulse generator also controls the emission of the P2 pulse, which is between the P1 and P3 pulses.

The output signal of the transmitter 10 is via a switch 11a (this is an electronic switch but is shown as a mechanical switch for simplicity) forwarded. This switch is controlled so that the P1 and P3 pulses are directed to the transmit / receive switch 12 while the P2 pulse is directed to an antenna 13. Consequently, the switch 11a is during a P1, P2, P3 pulse train switched twice.

As already mentioned, the P1-P3 pulses reach the transmit / receive switch 12 and are forwarded by this to the antenna 14 shown schematically. This antenna contains a reflector 15 which is designed as a corner reflector. This creates a suitable radiation pattern generated. This radiation pattern is designated 16 in FIG., While the radiation pattern designated 17 is the radiation diagram for the antenna 13 via which the P2 pulse is radiated. Thus becomes the P1-P3 pulse train in the surveillance sector, which is assigned to the respective interrogation device, and the P2 pulse is emitted into the rest of the room. There is an overlap of the radiation in a certain area the P1-, P3-pulses and the P2-pulses, which however

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does not have a disruptive effect.

The transponder responses are received by the antenna 14 and are transmitted via the transceiver switch 12, which is now in its "receiving state" is forwarded. The response received is sent to a receiver 18 which performs the functions customary in radar devices Fulfills. It also contains a decoder to de-, encode. However, it is also possible to forward the codes emitted by the aircraft to the control center and only decode there. In this case, each transmitted code is assigned to a specific surveillance sector. This can be done, for example, by a time reference to the activation. After decoding the Codes, the vehicle with its identity is displayed in the control center by a monitoring device. the received signals can also be used for control purposes (e.g. control of illuminated signs).

So far it was assumed that the individual interrogators are connected to the control center via cables. However, it is also possible to connect to the control center via Establish radio connections. Another possibility is to use optical transmission lines.

In the exemplary embodiment according to FIG. 4, the P1 and P3 pulses are emitted from the interrogation stations 20, 21. The P2 pulses, however, are from other stations 22 and 23 on the opposite side of the taxiway are arranged, radiated. An interrogation station 20 therefore radiates when it is activated from the control center was, their P1 pulse from after a predetermined Time the P3 pulse follows. A certain time after receiving the P1 pulse, the corresponding station 22 radiates the P2 pulse. Through the radiation diagrams of the query

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gestations 20 and 21 each become a surveillance sector which is part of the taxiway to be monitored. Here, the embodiment according to FIG. 4 is similar to the embodiment according to Fig. 1. However, this embodiment differs in that the P2 pulse of a separate station is emitted in such a way that the P2 pulse "illuminates" the area not to be monitored .

The P2 pulse is used to limit the surveillance sector in the direction perpendicular to the taxiway axis. The limitation of the surveillance sector in the direction of the taxiway is done by choosing the radiation pattern, via that the pulses P1 and P3 are emitted. It is still possible to receive another P2 pulse from the interrogator 20, as in the exemplary embodiment according to FIG. 1, to be emitted.

In FIG. 5, an interrogation station 20 or 21 according to FIG. 4 is shown schematically. This station is about a Line 25 which connects a number of stations along one side of a runway. If the respective station was addressed in the manner described, the address is from a code detector 26 in the Interrogator recognized. If the correct code is received, a transmitter 27 is used to transmit the P1-P3 pulse pair activated. The emission takes place when the subsequent trigger pulse is recognized by a detector 28 became.

Stations like 22 or 23 have a relatively simple structure. They consist of a transponder that has a specific Time after receiving a P1 pulse .a P2 pulse radiates. Alternatively, it can also be triggered by a trigger pulse sent to the station via another

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Line is fed to be triggered. This line
then connects stations such as 22 and 23.

The interrogation stations each also contain a receiver 30 which receives the response signals emitted by the vehicle. This can be a cheaper and more easily constructed one
Be a recipient. Its output signal is passed via an amplifier 31 to the Kabel.25, via which it is to the
Headquarters is forwarded.

The radar devices, which each contain a transmitter for emitting the P1, P3 pulse pairs and a receiver,

are relatively simple. It can partly use the technology known from the manufacture of paging systems
be used. The devices contain a decoder that works in the same way as the code detector in a people search system. He receives

however, its signals not via radio but via a cable. When the appropriate code has been decoded, it triggers his own transmitter, which is also relatively simple is.

It is particularly advantageous that the response signals emitted by the interrogated aircraft via the response signals from other vehicles instead of in the individual
Inquiry stations can be processed further in the headquarters.

The function and purpose are discussed below
the emission of the P2 pulse. The "crosstalk" of a given station is limited by
the back diagram of the neighboring P2 pulse transmitter, the
emitted at the appropriate time. If / as in the

1, three interrogation stations N-1, N and

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N + 1 are provided, then there is a PI, P3 pulse radiation on the runway for each station and the P2 pulse continues to be radiated backwards. As a result, when station N is activated and the monitoring sector assigned to it is to be monitored, the following conditions exist are:

a) Only P1 and P3 pulses are received on the taxiway; this is an effective query.

b) Off the runway and on the same side as N, there are relatively weak P1 and P3 pulses. It is There is still a strong P2 pulse generated by the interrogator N's back diagram. From it there is one from the transponder on board the aircraft is arranged, unaccepted query and consequently no response signal is emitted by the transponder.

c) Off the runway, but on the opposite side On the side of N, an interrogation signal that cannot be processed by the transponder is generated in a similar manner. In this In this case, the P1 and F3 pulses come from the interrogator N and the P2 pulse is generated by the transmitter of the interrogator N, whose radiation diagram points in the same direction.

A radar sensor is explained in more detail with reference to FIG. 6. On a post (height = 4 feet, diameter * = 6 inches) a horn antenna 50 is attached, the opening of which has the dimensions 12 "χ 4". In the upper part of the post 51 is contain the receiving part and the transceiver switch, while the transmitter unit 'is contained in the lower part 52 The post is attached to the ground with an anchor 54

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and has a predetermined breaking point on its lower part 53. The electrical devices are connected to cable 55.

In the following, reference is made again to the above paragraphs a), b) and c) with reference to FIG. 7. In the 7, as in FIG. 1, three interrogation stations 1, 2 and 3 are shown on opposite sides of a runway. Two stations each emit signals at the same time if they have received the same address code.

■ of the two stations, however, will be different Signals emitted via different radiation patterns. From station 1, P2 pulses with a large Power radiated in such a way that the radiation diagram for the P2 pulse is on the side on which the station 1 is arranged, extends over a larger area than the radiation pattern of station 2 for the P1 and P3 pulses. At the time that station 1 is emitting the P2 pulse, station 1 is not emitting any P1, PS pulses away. At this point in time, however, the station 2 emits P1, P2 and P3 pulses, as with reference to FIG. 1 described. With this type of signal radiation Interrogation signals received from the transponder on board the aircraft only in the surveillance sector on the taxiway can be processed as query signals. The stations 2 and 3 become effective with the next address code switched. When these two stations have received their corresponding address code, they emit signals in a similar manner as described for the 'Figures 1 and. In this case, station 2 only radiates the pulse P2, and the station 3 radiates in the surveillance sector the pulses P1 and P3 and, in the reverse direction, the pulse P2. So in this case are to limit of the surveillance sector apart from the taxiway, there are no additional stations, as in the case of the

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game according to Fig. 4 is necessary.

In all those cases in which the radiation pattern through which the P2 pulse is emitted does not cover the surveillance sector, it is possible to use a P2, P1 pulse pair, that has a distance of 2 yus to radiate. In this case the P1 pulse has a much lower power than the P2 pulse. If a receiver receives such a pair of pulses, then it is blocked for 25 / us, so that it is in ' cannot receive a P1 ~, P3 pulse pair during this time. This is useful in areas where special Circumstances the P1, P3 pulses with a larger amplitude than the P2 pulse is received. The address codes that are issued to activate the interrogation stations, are at the same time to the recipient in the center and also transmitted to the evaluation device. They can still be evaluated to form time gates to select a specific antenna, which makes it possible to use the transponder responses with a specific surveillance sector to correlate.

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Claims (7)

Patent attorney Q 1 Π Q1? R Dipl.-Phys. Leo Thul W I U 3 I C J Kurz Strasse 8 7000 Stuttgart 30 G. Höfgen - P. Sothcott -? H.L. Cohrs 30-15-3 INTERNATIONAL STANDARD ELECTRIC CORPORATION, NEW YORK claims 1./Airport monitoring device, in particular for runways, taxiways and feeders, which interacts with secondary radar transponders that are on board aircraft or vehicles, these secondary radar transponders then emit secondary radar response signals when they are from along the area to be monitored, which is divided into several monitoring sectors, interrogation devices of the airport monitoring facility have received PI and P3 interrogation pulses at the prescribed interval, in which the secondary radar response signals are evaluated for monitoring and in which the aircraft / vehicles are displayed in a display direction, characterized in that each of the interrogators (.1, 2, 3) emits the P1 and PS secondary radar interrogation pulses and the P2 secondary radar control pulse via different directional diagrams (Fig. 3) in such a way that the signal amplitudes of the P1 and P3 -Abfrageimpulse approximated only in this interrogator z regulated surveillance sector by the value prescribed for secondary radar is greater than the signal amplitude of the P2 control pulse. 2. Airport surveillance device according to claim 1, characterized in that the P2 control pulse is emitted in such a way that it is in a surveillance sector, with the exception of the surveillance sector assigned to the respective interrogation device Sm / Gn
02/26/81 130061/0606 G. Hofgen 30-15-3 The largest possible area of the airport to be monitored can be received. 3. Airport surveillance device, in particular for runways, taxiways and i'.ubringer, which interacts with secondary radar transponders that are on board aircraft or vehicles, these secondary radar transponders then emit secondary radar response signals when they are from Interrogation devices of the airport surveillance device arranged along the area to be monitored, which is divided into several surveillance sectors, have received P1 and P3 interrogation pulses at the prescribed interval, at which the secondary radar response signals are evaluated for monitoring and in which the aircraft / vehicles are displayed in a display direction are, characterized in that a transponder (22, 23) is provided opposite each interrogation device (20, 21), which emits the P2 secondary radar control pulse after receiving a P1 secondary radar interrogation pulse, and that the interrogation pulses and the control pulse in such a way via different directional diagrams be emitted that the signal amplitudes of the P1 and P3 interrogation pulses are approximately only in the monitoring sector assigned to this interrogation device by the value prescribed for secondary radar greater than the signal amplitude of the P2 control pulse. 4. Airport surveillance device according to claim 3, characterized in that the P2 control pulse is emitted in such a way that it can be received in the largest possible area of the airport to be monitored, with the exception of the surveillance sector assigned to the respective interrogation device. 5. Airport surveillance device according to claim 3 or 130061/0806 G. Hofgen 30-15-3 Claim 4, characterized in / that the interrogators (20, 21) contain receivers which receive the signals reflected from an aircraft or vehicle located in the surveillance sector concerned, and that the information as to whether an echo signal is received from the surveillance sector concerned is forwarded to a control center. 6. Airport surveillance device according to one of claims T to 4 / characterized in that all the interrogators are connected to a control center via lines or radio, that the interrogators are activated from the control center, and that the response signals received from the interrogators are transmitted to the control center . 7. Airport surveillance device according to claim 5 and claim 6, characterized in that in addition to the response signals, the information as to whether an echo signal was received from the surveillance sector concerned is transmitted to the control center via the lines or radio. 130061/0606