JP2778559B2 - Secondary surveillance radar system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary surveillance radar system (mode S) used in an air traffic control system, and more particularly to a reduction in response time in data communication between an aircraft and the ground.

[0002]

2. Description of the Related Art Secondary surveillance radar (SSR: secon)
The dary surveylanceradar system consists of a ground-based SSR and an airborne transponder.

In particular, in the SSR mode S system of the secondary surveillance radar, the ground station sequentially specifies the individual addresses by interrogating the aircraft at regular intervals including the individual address corresponding to the aircraft in the interrogation signal. Only the aircraft responds and measures the location information of the aircraft.

In the SSR mode S system, not only the aircraft is monitored but also the aircraft designated by the address and the SS
The R mode S system has a function of forming a digital data link line with the ground station and transmitting and receiving various messages. The interval between sending and receiving this message was limited by the radar scanning cycle.

[0005] Conventionally, there is the following publication regarding a system for shortening data transmission in communication with a mobile body. (1) Publication No. JP-A-5-209959 (particularly, page 1, line 2 to line 9) (2) Publication No. JP-A-5-172939 (particularly, page 1 line 2 to 11) Line) In the above (1), the byte length of the transmission signal is added to the transmission data and transmitted, so that the byte length of the transmission signal is made variable and the transmission byte length is shortened by not sending unnecessary signals such as NULL. As a result, the transmission time is shortened. This means that the transmission time can be shortened according to the byte length of the data. It is difficult to expect an effect in shortening the response time. This is because the data transmission time is considerably smaller than the polling interval, and the expected value of the response time is almost determined by the polling interval.

[0006] Next, in the above (2), the period of receiving the response signal is predicted from the timing of the interrogation signal, and the receiving operation is performed in synchronization with the interrogation. In a complicated data communication, the response message from the aircraft is determined by the operation of the pilot, so that it is impossible to accurately predict the timing at which the message is issued. Therefore, in order to receive a response sooner, it is necessary to shorten the interval between queries made from the ground.

[0007]

In a secondary surveillance radar system which constantly inquires about an aircraft at a constant interval (scanning cycle), a transmission time of a downlink message from an aircraft (after a pilot makes a message transmission request,
The time it takes for the message to reach the ground system)
There is a problem in that it is not improved due to the limitation of the scanning cycle.

The reason is that in order to detect a new target or to continuously monitor an aircraft, it is necessary to ask a question at a fixed period. Further, if the period of the monitoring question for all aircraft is shortened, the monitoring is not performed. This is because the time for the data link to be implemented is shortened by the remaining time, and the data link capacity is reduced.

This is the same whether the antenna is an electronic scanning type or a mechanical scanning type. A mechanical rotary antenna is combined with an omnidirectional antenna, a mechanical rotary antenna is used for monitoring questions, and an omnidirectional antenna is used for a data link. If you use
Frequent transmission of downlink requests over an omni-directional antenna is undesirable because it reduces the effective data link communication time.

[0010] Further, even in the case of a secondary surveillance radar system for receiving position information using an omnidirectional antenna for an aircraft capable of acquiring its own altitude and position information, a data link message is transmitted and received. Since it is necessary to sequentially specify addresses for each acquired aircraft and ask the aircraft, the frequent transmission of a downlink request reduces the effective data link communication time, so that each antenna is There is no essential difference from the one used.

It is an object of the present invention to provide a secondary surveillance radar system capable of reducing the response time of communication in communication between an aircraft and the ground and realizing a substantial increase in communication speed.

[0012]

SUMMARY OF THE INVENTION A secondary surveillance radar system according to the present invention is a secondary surveillance radar system, in which an aircraft for which a downlink message is expected from an aircraft to the ground is selected, and another airplane is identified with respect to the selected aircraft. It is characterized by asking questions at a shorter question interval than aircraft. Further, it is preferable that the selection of the aircraft is performed by predicting whether or not a downlink message of the aircraft is expected based on the content of an uplink data link message at the time of interrogating the aircraft.

[0013] The secondary surveillance radar system may be a secondary surveillance radar using an electronic scanning antenna, a secondary surveillance radar consisting of a mechanical rotary antenna and an omnidirectional antenna for data communication, or an omnidirectional antenna. It is preferable to use a secondary surveillance radar for receiving position information from an aircraft and performing data link communication.

Further, in each of the secondary surveillance radar systems according to the present invention, a question to an aircraft expected to have a downlink message is given a predetermined priority when there is no target aircraft at the timing of a data link inquiry within a predetermined heading. And performing a data link inquiry to an aircraft in another direction in which a downlink message is expected according to the following.

[0015] The secondary surveillance radar system of the present invention increases the number of queries to the aircraft when a response from the aircraft can be expected. More specifically, after analyzing a message sent to an aircraft and sending a message that elicits a response from the aircraft, a response from the aircraft can be expected, so shorten the query interval to the aircraft and respond early. To bring out.

Although there are various types of messages to be transmitted to the aircraft, the transmitted messages can be analyzed by having a function of registering a frequently used message that elicits a response. By recording the response time statistics for past transmitted messages and calculating the average response time for key messages, it is possible to predict the average response time when similar messages appear. Thus, when the response is predicted, the response from the aircraft can be obtained quickly by performing the query with a short query interval.

[0017]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a functional system diagram of a secondary surveillance radar system having an electronic scanning antenna according to a first embodiment of the present invention, and a connection system between an aircraft as an associated device and a data link processing device. .

The question calculator 1 controls the timing of a question and a response, and outputs a question signal to the transmitting device 2. The output interrogation signal is converted into a high-frequency signal by the transmission device and transmitted to the aircraft 4 via the electronic scanning antenna 3. The aircraft outputs a response signal to the query and receives the response signal on the electronically scanned antenna. The received response signal is input to the receiving device 5, amplified, converted into digital data by the signal processing device 6, and input to the query calculator.

The question calculator decodes the response signal to calculate the height position information of the aircraft, and if there is a request for transmission data from the aircraft in the response signal, sets a schedule for re-questioning. Stand up. The inquiry signal is transmitted to the aircraft again, and the data received from the aircraft is output to the user who uses the data via the data link processing system 7.

Here, even when there is no request (downlink request) for transmission data (data link message) from the machine, the query computer responds to the already transmitted query signal (question including data link message in uplink). If a response (downlink data link message) from the aircraft can be expected, the response time is predicted, and a question to elicit the response message is scheduled. Then, by performing a series of questions to the aircraft in accordance with this schedule, a response is elicited earlier than in the case where this is not performed.

Whether or not a response from the aircraft to the already transmitted interrogation signal can be expected can be determined based on the type of message to be transmitted to the aircraft and the frequency data of the response. For example, a main transmission message is registered and used based on the contents of a transmission message that is analyzed and frequently used to elicit a response, or based on statistics of the frequency of obtaining the response.

The determination of the sending time of the query for extracting the downlink message is performed by predicting the time of the response (downlink request) from the aircraft. For example, a response time to a past transmission message is measured, and a statistical result of an average response time to a main message is registered and used for the prediction.

That is, whether or not a response (downlink data link message) from the aircraft can be expected and determination of the sending time of the inquiry are determined by the content of the transmission message (uplink data link message) transmitted to the aircraft. Is analyzed, and when a message similar to the message appears, each prediction information is acquired by referring to each registered content.

The means for selecting an aircraft expected to have a downlink message from the aircraft to the ground and the means for inquiring the selected aircraft at a shorter query interval than other aircraft are constituted by a query calculator. The processing flow is shown in FIG. FIG. 2 mainly shows functions related to question control in the question calculator. In the secondary surveillance radar (mode S) of the present invention, the mode of interrogating the aircraft is divided at certain time intervals as shown in FIG. 3, and the simultaneous interrogation timing is different from the mode A / C aircraft which is a conventional aircraft transponder. Mode S where monitoring has not started
Conduct monitoring surveillance questions. At the individual question timing, an individual monitoring question and a data link question of the captured mode S machine are implemented. The part marked with * in FIG. 2 is the function added according to the present invention.

Next, the operation of the additional component, which is a feature of the present invention, will be described.

In the data link inquiry procedure, when a data link message can be expected on the downlink from the aircraft, a monitoring inquiry is made to the aircraft at a shorter interval than other aircraft to confirm the presence or absence of the downlink message. When a downlink request (a transmission request for a downlink message) is received from the aircraft, an individual inquiry for extracting the downlink message is performed, and the downlink message is acquired.

FIG. 4 is a conceptual diagram of the operation of the general interrogation from the ground station, the individual interrogation, and the individual interrogation for extracting the downlink message in the secondary surveillance radar system having the electronic scanning antenna.

In the figure, thin solid lines indicate the beam directions at the time of simultaneous interrogation timing by electronic scanning in the direction of the arrow. In the simultaneous inquiry timing, the azimuth of the inquiry is continuously changed at a constant speed, and a 360-degree azimuth is searched for in a fixed time (for example, 4 seconds) like a mechanical rotary antenna. The dotted line indicates the beam direction at the individual interrogation timing between them. At the individual question timing, an individual monitoring question and a data link question of the mode S machine are performed, and the individual monitoring question is a question for the same direction in synchronization with the simultaneous question timing.

For the data link question, a question in the same direction as the individual monitoring question is preferentially executed for efficiency of scheduling. However, if there is no target aircraft for the data link question in the scheduled direction, a certain priority is given. According to the ranking, the data link query of the other direction and the monitoring query for shortening the response time of the present invention are performed.

In FIG. 4, it is assumed that the data link between the ground station and the target aircraft does not exist at the time of the individual question indicated by the dotted line, and a thick solid line which requires a reduction in the response time of the data link at that timing. , ', The operation of instantaneously switching the beam direction so as to ask the individual question (monitoring question) of the aircraft in the direction of', 'is shown. Such an individual question is repeated a required number of times in one scanning cycle under the same condition, thereby shortening the question interval. Further, the shortening of the inquiry interval is performed for a predetermined period to derive a downlink request and a downlink (including a data link message).

As described above, the response from the aircraft can be transmitted to the user quickly by performing the downlink prediction function and the extraction query of the downlink message based on the downlink prediction function in a timely manner.

Next, a secondary surveillance radar system having a mechanical rotary antenna according to a second embodiment of the present invention will be described with reference to FIG.

The question calculator 8 controls the timing of questions and responses in the same manner as in the embodiment of FIG. 1, and outputs a question signal to the transmitting device 9. The output interrogation signal is converted into a high-frequency signal by the transmission device and transmitted to the aircraft 12 via the mechanical rotary antenna 11 connected by the antenna switching device 10. The aircraft outputs a response signal to the query and receives the response signal on the mechanical rotary antenna. The received response signal is input to the receiving device 13 and amplified, and then the signal processing device 1
The data is converted into digital data at 4 and input to the question calculator.

The question calculator decodes the response signal, and if there is a request for transmission data from the machine, sets up a schedule for re-questioning. If the aircraft is still in the beam of the mechanical rotary aerial, it will again send an interrogation signal to the aircraft and transmit the received data via the data link processing system 15 to the user using the data. Output to

Further, even if there is no transmission data request from the airplane, if the aircraft can expect a response to the already transmitted inquiry signal, the inquiry computer predicts the response time and derives a response message. Schedule a question. The inquiry signal according to this schedule switches the antenna switching device and uses the omnidirectional antenna 16 so that an inquiry can be performed even when the mechanical rotary antenna is not facing the direction of the aircraft. By carrying out this question, a response message can be obtained earlier than in the case where it is not carried out.

The means for selecting an aircraft expected to have a downlink message from the aircraft to the ground and the means for inquiring the selected aircraft at shorter interrogation intervals than other aircraft are constituted by a query calculator. The processing flow is the same as in FIG.

As a third embodiment of the present invention,
A secondary surveillance radar system using an omnidirectional antenna will be described.

In recent years, technologies for acquiring own position information (latitude, longitude, altitude) such as a GPS system have been used in various fields, and the aircraft itself has this kind of measuring means.
When the position of the own aircraft can be measured, the ground station can construct a system for monitoring the position of the aircraft by receiving the information of the own location of the aircraft broadcast at a certain interval from the aircraft.

Specifically, the aircraft is equipped with a GPS device, and the ground station captures the aircraft in each direction by receiving a random scatter response for a certain period of time based on a position report including an address from each aircraft. I do. Since then
By performing a data link (uplink and downlink) with a certain priority to the captured aircraft in each direction, a secondary surveillance radar system that acquires necessary position information and performs communication by a data link line can be realized.

Also in this system, an aircraft for which a downlink message can be expected is selected, and in an inquiry operation for an aircraft for each direction, an aircraft for which a downlink message can be expected is used by using an inquiry time for an azimuth where no aircraft exists. By repeating the interrogation even within the scan cycle, interrogation at shorter intervals than other aircraft can be performed.

Also in the present embodiment, the selection of the aircraft and the question control with a short query interval are performed by the query calculator. The processing flow is the same as in FIG.

As can be seen from the processing flow of FIG. 2, if the secondary surveillance radar system according to each of the embodiments of the present invention is used, a step of transmitting an uplink question to an aircraft, Performing a data communication method using a secondary surveillance radar, comprising: selecting an aircraft expected to receive a downlink response from the aircraft based on the selected aircraft; and querying the selected aircraft at a shorter query interval than other aircraft. Can be.

[0044]

According to the present invention, the response time from an aircraft can be reduced. The reason is that the response can be obtained early by shortening the interval between questions from the ground to the aircraft.

As a specific example of the effect, the transmission time of a downlink message in a secondary surveillance radar system consisting of only a mechanical rotary antenna is compared with the transmission time of the present invention.

Assuming that the rotation period of the mechanical rotary antenna is 4 seconds, which is a typical value for airport monitoring, in a conventional secondary surveillance radar system, a pilot requests a transmission of a downlink message before a secondary surveillance. The average expected value until the downlink message is received by the radar system is 2 seconds because the antenna is rotating at a constant speed, and is distributed over a transmission time of 0 seconds at the minimum and 4 seconds at the maximum. On the other hand, in the method of the present invention, if the aircraft whose response is predicted is interrogated every second, the average expected value from the transmission request to the reception of the downlink message becomes 0.5 seconds, It is distributed over a transmission time of a minimum of 0 seconds and a maximum of 1 second. Thus, as an effect of the present invention, it is possible to reduce the average expected transmission time by 1.5 seconds and the maximum by 3 seconds.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram showing an embodiment of a secondary surveillance radar system (mode S) having an electronic scanning antenna according to the present invention.

FIG. 2 is a diagram showing a flow of a question schedule process performed in a question calculator of the secondary surveillance radar system (mode S) of the present invention.

FIG. 3 is a diagram showing a processing timing of a question schedule process performed in a question calculator.

FIG. 4 is a diagram showing the concept of a simultaneous question, an individual monitoring question, and a data link question.

FIG. 5 is a system configuration diagram showing another embodiment of a secondary surveillance radar system (mode S) having a mechanical rotary antenna and an omnidirectional antenna according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 query calculation 2 transmitting device 3 electronic scanning antenna 4 aircraft 5 receiving device 6 signal processing device 7 data link processing device 8 query calculator 9 transmitting device 10 antenna switching device 11 mechanical rotary antenna 12 aircraft 13 receiving device 14 signal processing device 15 data Link processing system 16 Omnidirectional antenna

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01S 13/00-13/95

Claims (3)

(57) [Claims] 1. A secondary surveillance radar system comprising an interrogator, wherein the interrogator selects an aircraft for which a downlink message from the aircraft to the ground is expected.
A secondary surveillance radar system comprising: means for differentiating; and means for interrogating the selected aircraft at a shorter interrogation interval than other aircraft. 2. The method according to claim 1, wherein the selection of the aircraft is performed by predicting whether or not a downlink message of the aircraft is expected based on the content of an uplink data link message at the time of interrogating the aircraft. Item 2. A secondary surveillance radar system. 3. A navigation for which a downlink message is expected.
For questions to the aircraft, use the data link question
Predetermined priority when there is no target aircraft in mining
According to other directions where downlink messages are expected
3. The secondary surveillance radar system according to claim 1 , wherein a data link inquiry to the aircraft is performed .