JP2012177660A - Secondary surveillance radar device and data processing program for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary surveillance radar device by which highly reliable altitude information with less errors is obtained.SOLUTION: A secondary surveillance radar device in an embodiment includes: a transmission unit which continuously transmits a query signal for obtaining altitude information to a transponder to be mounted on an aircraft for a plurality of times; a reception unit which receives a plurality of response signals to be transmitted from the transponder in response to the query signal; a code conversion unit which converts pieces of data on the plurality of received response signals into a plurality of pieces of altitude data, respectively; and a data processing unit which determines, in first and second pieces of continuous altitude data among the plurality of pieces of altitude data, that the first and second pieces of altitude data are correlated with each other when second altitude shown by the second altitude data received later is within a predetermined allowable range to first altitude shown by the first altitude data received first, and outputs the second altitude as altitude information on the aircraft.

Description

  The present invention relates to a secondary monitoring radar apparatus and its data processing program.

  Secondary Surveillance Radar (SSR) used for air traffic control, etc. transmits an interrogation signal to a transponder mounted on an aircraft, receives a response signal from the transponder, and receives aircraft identification information and Get altitude information.

  The secondary monitoring radar apparatus system is classified into modes such as mode A, mode C, and mode S depending on the type of information to be obtained. Of these modes, mode A is a mode for acquiring aircraft identification information that is uniquely assigned each time the aircraft takes off from the aircraft in flight. Mode C is a mode for acquiring aircraft altitude information from a flying aircraft (see, for example, Patent Document 1).

JP 2007-33408 A

  Many specifications of secondary surveillance radar equipment in Japan are based on specifications established by the Federal Aviation Administration (FAA). For example, in the specifications related to Mode C that have been used conventionally, if there is a difference of 2 bits or more between each data sequence included in two consecutive response signals, it is determined that there is no correlation, and the received response signal Reject the included altitude information. On the other hand, if the difference between the data strings of the two response signals is within 1 bit, it is determined as “correlated”, and usually the altitude information included in the response signal received later is adopted as correct information. Yes.

  However, according to this specification, even if there is an error of 1 bit, if an error occurs in a bit at a position where the weight is large, there is a possibility of having a large error as altitude information.

  Therefore, there is a demand for a secondary monitoring radar apparatus that can obtain altitude information with higher reliability and fewer errors.

  The secondary monitoring radar according to the embodiment transmits a question signal for obtaining altitude information to a transponder mounted on an aircraft a plurality of times in succession, and is transmitted from the transponder in response to the question signal. A receiving unit that receives a plurality of response signals, a code conversion unit that converts the data of the received plurality of response signals into a plurality of altitude data, and first and second altitudes that are consecutive among the plurality of altitude data In the data, when the second altitude indicated by the second altitude data received later is within a predetermined allowable range with respect to the first altitude indicated by the first altitude data previously received, A data processing unit that determines that the first and second altitude data are correlated and outputs the second altitude as the altitude information of the aircraft.

The block diagram which shows the structural example of the secondary monitoring radar apparatus of this embodiment. The figure which shows the hardware structural example of the computer used with a secondary monitoring radar apparatus. The figure which shows typically the relationship between an inquiry pulse train and a response pulse train. The figure explaining the problem of the conventional secondary monitoring radar apparatus. The figure which shows an example of the advanced information processing of the secondary monitoring radar apparatus of this embodiment, and its flow. The figure explaining a 1st Example. The figure explaining a 2nd Example. The figure explaining a 3rd Example. The figure explaining a 4th Example. The figure explaining a 5th Example.

  Hereinafter, embodiments will be described with reference to the accompanying drawings.

(1) Configuration FIG. 1 is a block diagram illustrating a configuration example of a secondary surveillance radar device 1 (SSR: Secondary Surveillance Radar) according to the present embodiment. The secondary monitoring radar device 1 is a device installed on the ground, transmits a question signal (question pulse train) 102 to a transponder 101 mounted on the aircraft 100, and responds to the question signal 101 from the transponder 101. A response signal (response pulse train) 103 to be transmitted is received.

  The secondary monitoring radar device 1 includes, for example, an antenna 10, a transmission unit 11, a reception unit 12, a code conversion unit 14, a data processing unit 15, and the like.

  The antenna 10 forms a transmission / reception beam having a predetermined azimuth beam width and transmits an interrogation pulse train to the aircraft while mechanically rotating continuously around the entire circumference, for example, while receiving a response pulse train from the transponder 101.

  Transmitter 11 continuously transmits a high-frequency signal modulated with an interrogation pulse train for obtaining altitude information to transponder 101 mounted on aircraft 100 a plurality of times. Similarly, the inquiry pulse train for obtaining the identification information of the aircraft 100 is continuously transmitted a plurality of times.

  A mode for obtaining identification information is called mode A, and a mode for obtaining altitude information is called mode C. Mode A and mode C differ in the type of interrogation pulse train.

  The receiving unit 12 receives and demodulates the mode A and mode C response signals (high frequency signals) transmitted from the transponder 101 in response to each interrogation pulse train, and outputs a plurality of response pulse trains to the subsequent stage.

  Normally, the interrogation pulse train is constantly transmitted at a predetermined repetition period, for example, a period of 2 msec, but is transmitted to the transponder 101 only during a passing period in which the main beam of the rotating antenna 10 passes through the aircraft 100. Therefore, the number of repetition cycles during this passage period is substantially the number of interrogation pulse trains transmitted continuously to the transponder 101.

  The response pulse train obtained from the transponder 101 is data in which identification information and altitude information during flight (binary number data) are encoded by a Gray code. The code conversion unit 14 converts the gray code data into binary data. By converting the mode C response pulse train from gray code to binary data, a plurality of altitude data of the aircraft 100 sent from the transponder 101 is obtained during the passage of the main beam.

  The data processing unit 15 includes, in the first and second altitude data that are continuous among the plurality of altitude data, the second altitude indicated by the second altitude data received later is the first altitude data that has been received first. When the first altitude data is within a predetermined allowable range with respect to the first altitude indicated by the altitude data, it is determined that the first altitude data and the second altitude data are correlated, and the second altitude is determined as the altitude of the aircraft. Output as information. More specific processing of the data processing unit 15 will be described later.

  The code conversion unit 14 and the data processing unit 15 can be configured using dedicated hardware, but may be configured as a computer 15 that causes a processor to execute a program in which a predetermined procedure is described.

  FIG. 2 is a configuration example of the computer 13. The computer 13 includes, for example, a processor 20, a ROM 21, a RAM 22, a storage unit 23 such as an HDD, an external I / O 24, and the like. A program for executing the processing of the code conversion unit 14 and the data processing unit 15 is stored in the ROM 21 or the storage unit 23 and is executed by the processor 20. The RAM 22 functions as a work area for the processor 20. The external I / O 24 inputs the response pulse train received by the receiving unit 12 and outputs altitude information and identification information obtained by executing the program to the outside.

(2) Operation FIG. 3 is a diagram schematically showing the relationship between the interrogation pulse train and the response pulse train. In FIG. 3, “A” indicates mode A, and “C” indicates mode C.

  The interrogation pulse trains of mode A and mode C both have two pulses (P1 and P3), but the interval between the two pulses is different between T1 and T2. Due to the difference between T1 and T2, the transponder 101 can identify both. The repetition period Tr of the interrogation pulse train is, for example, 2 msec, but is not limited to this value, and is appropriately determined depending on the rotation speed of the antenna 10, the beam width, and the like.

  An identification response pulse train is returned from the mode A interrogation pulse train, and an advanced response pulse train is returned from the transponder 101 as a gray code to the mode C interrogation pulse train. The numbers such as (N), (N + 1), and (N + 2) assigned to each response pulse train in FIG. 3 indicate the time series numbers of the mode A and mode C response pulse trains.

  In the present embodiment, the mode A process is basically the same as the conventional process, and the mode C process is different from the conventional process. Accordingly, only the mode C process will be described in the following description.

  FIG. 4 is a diagram illustrating a correlation determination method in a conventional secondary monitoring radar apparatus as a comparative example to the correlation determination method of the secondary monitoring radar apparatus 1 according to the present embodiment. In the conventional correlation determination method, as shown in the upper part of FIG. 4, the correlation determination and the correlation count determination are performed with the gray code as it is. In the conventional correlation determination, if the difference between the gray codes of two highly-responsive pulse trains received successively is 1 bit or less, the two highly-responsive pulse trains are determined to be “correlated”. Aircraft identification information is fixed, but altitude changes from moment to moment. Therefore, a 1-bit difference is allowed between two consecutive altitudes.

  In the correlation count determination, when “with correlation” continues for a predetermined number of times, the last gray code is extracted. Then, only the last extracted gray code is subjected to gray code conversion for converting gray code to binary data to obtain final altitude information. This altitude information is output to the outside.

  The lower part of FIG. 4 illustrates a conventional process for three high response pulse trains (N), (N + 1), and (N + 2). Of these, it is assumed that the advanced response pulse train (N + 2) includes a false pulse due to interference or the like. The altitudes when the altitude response pulse trains (N), (N + 1), and (N + 2) are subjected to Gray code conversion are assumed to be 10,000 feet, 9900 feet, and 20000 feet, respectively. The altitude response pulse train (N + 2) assumes that a false pulse is generated at a bit position having a large weight. Therefore, the altitude response pulse train (N + 2) is greatly different in value from the other two altitudes.

  According to the above-described conventional correlation determination method, the three high response pulse trains (N), (N + 1), and (N + 2) illustrated in FIG. 4 are processed as follows. First, a difference between two Gray code bits of the high response pulse train (N) and the high response pulse train (N + 1) is determined. In this example, since the bit difference is 1 bit, it is determined that the two Gray codes are “correlated”. Next, the difference between the two Gray code bits of the advanced response pulse train (N + 1) and the advanced response pulse train (N + 2) is determined. Also in this case, since the difference between the two bits is 1 bit, the two gray codes are still determined as “correlated”.

  If the predetermined number of times in the correlation number determination is 2 and the altitude response pulse train (N + 2) is the last data, the altitude response pulse train (N + 2) is subjected to Gray code conversion and output to the outside as altitude information. . In other words, although the altitude of the altitude response pulse train (N + 2) has a large error due to the false pulse, the gray code bit difference is 1 bit. The altitude information you have will be output to the outside.

  In the secondary monitoring radar apparatus 1 according to the present embodiment, the processing shown in FIG. 5 is performed in order to solve such a conventional problem.

  First, in step ST1, gray code conversion is performed prior to correlation determination (step ST2) and correlation count determination (step ST3), and an altitude response pulse train input from the receiving unit 12 is sequentially converted from gray code to altitude as binary data. Convert to data.

  In step ST2, a correlation is determined for each converted altitude data, and “continuous correlation” or “no correlation” is sequentially determined for two consecutive altitude data. The correlation determination is performed using the first correlation condition and the second correlation condition.

  The first correlation condition is whether or not the subsequent altitude data among the two consecutive altitude data is within a predetermined allowable range (± α) of the previous altitude data. If the later altitude data is within the allowable range of the previous altitude data, the two altitude data are determined to be “correlated”, and if they are outside the allowable range, it is determined to be “no correlation”. The allowable range is determined based on an assumed altitude change of the aircraft during the repetition period Tr. The allowable range is set to ± 500 feet, for example, but is not limited to this value. Moreover, it is preferable that the allowable range is configured to be changeable.

  The second correlation condition is the presence or absence of continuity of ascending or descending. If at least two altitude data are obtained, it can be determined whether the aircraft is ascending or descending based on the magnitude relationship between the altitude data and the temporal relationship.

  If it is determined that the aircraft is rising from at least two preceding altitude data, it can be shown that the newly obtained altitude data continues to rise, that is, one new altitude data is obtained. If the altitude greater than the previous altitude data is indicated, it is determined that there is a correlation between the newly obtained altitude data and the previous altitude data. On the other hand, if it shows that it is descending, it is determined that there is no correlation.

  On the other hand, if it is determined that the aircraft is descending from at least two preceding altitude data, if the newly obtained altitude data continues to decline, that is, the newly obtained altitude data If the altitude is smaller than the previous altitude data, the newly obtained altitude data and the previous altitude data are considered to have downward continuity. On the other hand, if it shows that it is rising, it is determined that there is no correlation.

  Both the first correlation condition and the second correlation condition may be applied, but only the first correlation condition may be applied.

  In the correlation count determination in step ST3, the last altitude data is output to the outside as altitude information only when “with correlation” continues for a predetermined number of times (M times) or more. The predetermined number of times is, for example, 3 to 5 times, but is not limited to this value. The predetermined number of times is preferably configured to be changeable.

  The correlation count determination in step ST3 may be omitted. In this case, when only the first correlation condition is applied to the correlation determination, if “with correlation” is at least once, the later altitude data is output as altitude information. When both the first and second correlation conditions are applied to the correlation determination, the last altitude data is output as altitude information if “correlation” is at least twice.

(3) Embodiment FIG. 6 is a diagram illustrating a first embodiment when only the first correlation condition is applied to the correlation determination and the correlation count determination is omitted. In this embodiment, the allowable range in the first correlation condition is set to ± 500 feet. In this embodiment, the altitude of the altitude response pulse train (N) subjected to Gray code conversion is 10100 feet, and the altitude of the altitude response pulse train (N + 1) subjected to gray code conversion is 10200 feet. Since the altitude difference is 100 feet and is within an allowable range (± 500 feet), the two altitude data are determined to be “correlated” and the subsequent altitude data “10200 feet” is externally provided as altitude information. Is output.

  FIG. 7 is a diagram illustrating a second embodiment when the first correlation condition is applied to the correlation determination and the correlation count determination is omitted, as in FIG. 6. In this embodiment, the first two pulse trains are the same as in the first embodiment, the altitude of the altitude response pulse train (N) converted to gray code is 10100 feet, and the altitude of the altitude response pulse train (N + 1) converted to gray code is 10200 feet. On the other hand, the third altitude response pulse train (N + 2) is affected by interference and the like, and a 1-bit pulse is not detected, and the altitude after gray code conversion is 9800 feet.

  However, the difference between the second altitude data and the third altitude data is 400 feet, which is within ± 500 feet of tolerance. Therefore, the second altitude data and the third altitude data are also determined as “correlated”. Since the third altitude data is the last altitude data, the altitude “9800 feet” is output to the outside as altitude information.

  In the second embodiment, since the third advanced response pulse train (N + 2) is affected by interference or the like, although it is strictly data having an error, the error is a small error within an allowable range. Yes, it has no serious impact.

  FIG. 8 shows the same conditions for the continuity of ascending and descending (first) in addition to the first correlation condition for the same three altitude response pulse trains (N), (N + 1), (N + 2) as in the second embodiment. It is a figure which shows the 3rd Example to which 2 correlation conditions) are applied.

  From the altitudes (10100 feet and 10200 feet) of the first and second altitude response pulse trains (N) and (N + 1), it is determined that the aircraft is ascending. On the other hand, the altitudes (10200 feet and 9800 feet) of the second and third altitude response pulse trains (N + 1) and (N + 2) indicate that the aircraft is descending. Therefore, the second and third altitude data satisfy the first correlation condition, but do not satisfy the second correlation condition of continuity of ascending or descending.

  As a result, in the third embodiment, the altitude data of the third altitude response pulse train (N + 2) having an error due to the influence of interference or the like is rejected, and the altitude data of the previous altitude response pulse train (N + 1) is rejected. Data (10200 feet) will be output to the outside as altitude information.

  In the third embodiment, the reliability of the advanced information is increased by making the correlation condition more strict.

  FIG. 9 is a diagram showing a fourth embodiment. In this embodiment, both the first correlation condition and the second correlation condition are applied as in the third embodiment, but the third advanced response pulse train (N + 2) is different from that in FIG. In the third advanced response pulse train (N + 2) in the fourth embodiment, a false pulse due to interference or the like is generated at a position where the bit weight is large. As a result, the altitude data of the altitude response pulse train (N + 2) shows a large value of 20000 feet. Although the second correlation condition of continuity of ascending or descending is satisfied, the difference between the second and third altitude data is large and greatly deviates from the first correlation condition. Therefore, also in the fourth specific example, altitude data (10200 feet) of the second altitude response pulse train (N + 1) is output to the outside as altitude information. Also in this specific example, the reliability of altitude information is enhanced by applying both the first correlation condition and the second correlation condition.

  FIG. 10 is a diagram showing a fifth embodiment. In the fifth embodiment, the correlation number determination (step ST3) is performed after the correlation determination (step ST2).

  In the example shown in the upper part of FIG. 10, a determination condition of “output last altitude data as altitude information when three or more correlations continue” is applied as the correlation count determination. As a result, the first two high response pulse trains (N) and (N + 1) are “correlated”, but the third high response pulse train (N + 2) is “no correlation”, so the high response pulse train (N + 1) ) Altitude data is rejected. On the other hand, the altitude response pulse trains (N + 3) to (N + 6) are “correlated” four times in succession and satisfy the above-described determination condition. Therefore, altitude data of the altitude response pulse train (N + 6) that is finally determined to be “correlated” is output to the outside.

  By performing the correlation count determination, the reliability of altitude information output to the outside can be further enhanced.

  As described above, according to the secondary monitoring radar apparatus 1 and its data processing program according to this embodiment, altitude information with higher reliability and fewer errors can be output to the outside. The reliability of control can be improved.

  Although several embodiments have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 Secondary monitoring radar apparatus 10 Antenna 11 Transmission part 12 Reception part 13 Computer 14 Code conversion part 15 Data processing part 101 Transponder

Claims (8)

A transmission unit that continuously transmits a question signal for obtaining altitude information to a transponder mounted on an aircraft a plurality of times,
A receiving unit for receiving a plurality of response signals respectively transmitted from the transponder in response to the consecutive interrogation signals;
A code converter that converts the received data of the plurality of response signals into a plurality of altitude data representing altitude;
In the first and second altitude data that are continuous among the plurality of altitude data, the second altitude indicated by the second altitude data received later is the first altitude data received earlier. When the first altitude shown is within a predetermined tolerance, the first altitude data and the second altitude data are determined to be correlated, and the second altitude is output as altitude information of the aircraft. A data processing unit;
A secondary monitoring radar apparatus comprising: The data processing unit
Determining whether the aircraft is ascending or descending from a plurality of altitude data obtained before the second altitude data;
When the second altitude is within the predetermined tolerance with respect to the first altitude and the second altitude is an altitude indicative of continuity of ascending or descending of the aircraft, Determining that the first and second altitude data are correlated, and outputting the second altitude as altitude information of the aircraft;
The secondary monitoring radar apparatus according to claim 1. The data processing unit
When it is determined that there is a correlation between the first and second altitude data continuously for a predetermined number of times, the last obtained second altitude is output as altitude information of the aircraft.
The secondary monitoring radar apparatus according to claim 1 or 2, wherein The predetermined allowable range is configured to be changeable,
The secondary monitoring radar apparatus according to claim 1. The predetermined number of times is configured to be changeable,
The secondary monitoring radar apparatus according to claim 3. A plurality of response signals are transmitted from the transponder in response to each of the consecutive interrogation signals by continuously transmitting a plurality of interrogation signals for obtaining altitude information to the transponder mounted on the aircraft. A first procedure for converting each of the data into a plurality of altitude data representing altitude,
In the first and second altitude data that are continuous among the plurality of altitude data, the second altitude indicated by the second altitude data received later is the first altitude data received earlier. When the first altitude shown is within a predetermined tolerance, the first altitude data and the second altitude data are determined to be correlated, and the second altitude is output as altitude information of the aircraft. 2 steps,
A data processing program for a secondary monitoring radar apparatus, characterized in that a computer is executed. When the third altitude data received before the first altitude data is greater than the first altitude data, it is determined that the aircraft is descending, and the third altitude data is the first altitude data Causing the computer to further execute a procedure for determining that the aircraft is rising when the altitude data is smaller than
The second procedure is:
If it is determined that the aircraft is descending, the second altitude is within the predetermined allowable range with respect to the first altitude, and the second altitude is greater than the first altitude. Determining that the first and second altitude data are correlated when low, and outputting the second altitude as altitude information of the aircraft;
If it is determined that the aircraft is rising, the second altitude is within the predetermined allowable range with respect to the first altitude, and the second altitude is higher than the first altitude. Determining that the first and second altitude data are correlated when high, and outputting the second altitude as altitude information of the aircraft;
The data processing program for the secondary monitoring radar apparatus according to claim 6, wherein the data processing program is a procedure. The second procedure is:
When it is determined that there is a correlation between the first and second altitude data continuously for a predetermined number of times, the last obtained second altitude is output as altitude information of the aircraft.
8. The data processing program for a secondary monitoring radar apparatus according to claim 6, wherein the data processing program is a procedure.

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