Alarm suppressing system in aircraft collision avoidance system

• US 4,978,945 A
• Filed: 06/30/1989
• Issued: 12/18/1990
• Est. Priority Date: 10/17/1985
• Status: Expired due to Fees

• Current Assignee: Miyazaki Epson Corp. (Seiko Group)
• Original Assignee: TOYO Communication Equipment Company Limited
• Inventors: Funatsu, Chuhei
• Primary Examiner(s): Orsino, Joseph A.
• Assistant Examiner(s): Swarthout, Brent A.
• Application Number:
  US07/373,205
• Time in Patent Office: 536 Days
• Field of Search: 340/961, 340/963, 364/461, 364/439, 342/29, 342/30, 342/32, 342/36-38, 342/455
• US Class Current: 340/961
• CPC Class Codes: G01S 13/782 using multimoding or selective addressing
• CPC Class Codes: G01S 13/91 for traffic control G01S13/93 takes precedence
• CPC Class Codes: G01S 13/933 of aircraft or spacecraft
• CPC Class Codes: G08G 5/0008 with other aircraft
• CPC Class Codes: G08G 5/0013 with a ground station
• CPC Class Codes: G08G 5/0065 for taking-off
• CPC Class Codes: G08G 5/0082 for monitoring traffic from a ground station radar or analogous systems specially adapted for traffic control G01S13/91
• CPC Class Codes: G08G 5/025 Navigation or guidance aids radar or analogous systems specially adapted for landing purposes G01S13/913

Abstract

The present invention is concerned with a system in which when the altitude of a subject aircraft becomes lower than a predetermined altitude, a warning limit value is reduced or made equal to zero on the minimum altitude side whereby a useless alarm based on response signals delivered from other aircraft staying in or taxiing in the airport are suppressed.

Claims

1. An alarm suppressing system for an aircraft collision avoidance system which has a function of determining whether or not a subject aircraft is in danger of colliding with other aircraft and which generates an alarm when it has determined that the subject aircraft is in danger of colliding with another aircraft, through utilization of a response signal received from said other aircraft, said alarm suppressing system comprising a filtering circuit and said collision avoidance system comprising:

a receiver for receiving at least said response signal from said other aircraft;

a first encoder for encoding said received response signal into a required signal;

an altitude information detector for detecting altitude information of said subject aircraft;

a second encoder for encoding the output signal of said altitude information detector into a required signal;

a first comparator for comparing the outputs of said first and second encoders;

a collision avoidance system logic circuit which receives the output of said receiver via filtering circuit of said alarm suppressing system and determines whether or not said subject aircraft is in danger of midair collision with said other aircraft in accordance with said output of said receiver.

said alarm suppressing system comprising;

a second comparator for comparing the output of said first comparator and the output of said second encoder;

said filtering circuit which is supplied with the output of said receiver and is controlled by the output of said second comparator;

wherein when an altitude difference between said subject aircraft and said other aircraft is equal to the altitude of said subject aircraft and said other aircraft is at an altitude lower than said subject aircraft, it is determined that said subject aircraft is staying on the ground, and the generation of an alarm is prevented on the basis of said response signal received from said other aircraft.

2. An alarm suppressing system for an aircraft collision avoidance system which has a function of determining whether or not a subject aircraft is in danger of colliding with other aircraft and which generates an alarm when it has determined that the subject aircraft is in danger of colliding with another aircraft, through utilization of a response signal received from said other aircraft, said alarm suppressing system comprising a gate circuit and said collision avoidance system comprising:

a receiver for receiving at least said response signal from said other aircraft;

a response detector for detecting said received response signal;

a mode discriminator which receives the output of said response detector and discriminates the mode of reception of said response signal;

an antenna switch switchable between low and high altitude side antennas;

an antenna discriminator operatively associated with said antenna switch, for determining which of said antennas is in use;

a computer which receives the output of said response detector via a gate circuit and determines whether or not said subject aircraft is in danger of midair collision with said other aircraft in accordance with said output of such response detector; and

a display;

said alarm suppressing system comprising;

an altitude detecting means for determining the altitude of the subject aircraft;

an analog-to-digital converter for converting the altitude of said subject aircraft into a predetermined code;

an altitude discriminator which receives the output of said analog-to-digital converter and determines the altitude of said subject aircraft;

a logic circuit which is supplied with the outputs of said antenna discriminator, said mode discriminator and said altitude discriminator; and

said gate circuit for controlling the output of said response detector by the output of said logic circuit;

wherein when said response signal from said other aircraft is received by said low altitude side antenna, and when said received response signal is of Mode A and the altitude of said subject aircraft is lower than a predetermined value, said received response signal from said other aircraft is inhibited from being input to the aircraft collision avoidance equipment mounted on said subject aircraft, thereby preventing the generation of a useless alarm.

3. An alarm suppressing system for an aircraft collision avoidance system which has a function of determining whether or not a subject aircraft is in danger of colliding with other aircraft and which generates an alarm when it has determined that the subject aircraft is in dange of colliding with another aircraft, through utilization of a response signal received from said other aircraft, said alarm suppressing system comprising a filtering circuit and said collision avoidance system comprising:

a receiver for receiving at least said response signal from said other aircraft;

a response detector for detecting said received response signal;

a computer which receives the output of said response detector via a filtering circuit and determines whether or not said subject aircraft is in danger of midair collision with said other aircraft in accordance with said output of said response detector; and

a display;

said alarm suppressing system comprising;

a radio altitude detecting means for determing the altitude of the subject aircraft;

an atmospheric altitude detecting means mounted on said subject aircraft;

an encoder for receiving outputs from said radio altitude detecting means and said atmospheric altitude detecting means and for providing predetermined codes in response to said outputs;

a ground altitude calculating machine which receives the outputs of said encoder and said response detector, computes the atmospheric pressure on the ground, and compares said atmospheric pressure on the ground and altitude information derived from atmospheric pressure information contained in said response signal received from said other aircraft;

a filtering circuit which receives an output from the response detector and which is controlled by said ground altitude calculating machine;

wherein when said response signal received from said other aircraft is of mode C, ground atmospheric pressure information is computed on the basis of a signal available from said altitude detector of said subject aircraft, altitude information based on atmospheric pressure is extracted from said mode C response signal, said extracted altitude information and said atmospheric pressure information are compared by said ground altitude calculating machine, which determines whether said other aircraft having delivered said response signal is staying at an airport or is in flight, and said filtering circuit is controlled on the basis of the result of said determination so that said response signal from said other aircraft staying at said airport is prevented from being supplied to the aircraft collision avoidance equipment mounted on said subject aircraft, thereby preventing the generation of useless alarm.

4. An alarm suppressing system for an aircraft collision avoidance system which has a function of determining whether or not a subject aircraft is in danger of colliding with other aircraft and which generates an alarm when it has determined that the subject aircraft is in danger fo colliding with another aircraft, through utilization of a response signal received from said other aircraft, said alarm suppressing system comprising a filtering circuit and said collision avoidance system comprising:

a receiver for receiving said response signal from said other aircraft;

a response signal detector for directing said received response signal;

a computer which receives an output of a filtering circuit of said alarm suppressing system and determines whether or not said subject aircraft is in danger of midair collision with said other aircraft; and

a display;

said alarm suppressing system comprising;

a receiver for receiving from an airport control center information concerning the atmospheric pressure at an airport and in its vicinity from an airport control center;

an encoder for encoding the output of said receiver;

a ground altitude calculating machine whereby altitude information based on atmospheric pressure is extracted from said received response signal of said other aircraft and said altitude information and said atmospheric information received from said airport control center are compared;

said filtering circuit which is controlled by an output of said ground altitude calculating machine and controls an output of said response signal detector;

wherein when said received response signal of said other aircraft is of mode C, said atmospheric pressure information received from said airport control center and altitude information derived from atmospheric information contained in said mode C response signal are compared by said ground altitude calculating machine, which determines whether said other aircraft transmitting said response signal is staying at said airport or is in flight, and on the basis of the result of said determination, the output of said response signal detector is prevented from input into said computer, thereby preventing the generation of a useless alarm.

5. An alarm suppressing system for an aircraft collision avoidance sytem which has a function of determining whether or not a subject aircraft is in danger of colliding with other aircraft and which generates an alarm when it has determined that the subject aircraft is in danger of colliding with another aircraft, through utilization of a response signal received from said other aircraft, said collision avoidance system comprising:

a receiver for receiving at least said response signal from said other aircraft;

an "ON THE GROUND" signal detector for detecting an "ON THE GROUND" signal contained in said response signal;

said alarm suppressing system comprising;

a filtering circuit for permitting and inhibiting the input of said received response signal to the aircraft collision avoidance system in accordance with the output of said "ON THE GROUND" signal detector;

wherein said when "ON THE GROUND" signal is contained in said received response signal of said other aircraft, said received response signal is inhibited from being input to aircraft collision avoidance equipment mounted on said subject aircraft, thereby preventing a useless alarm from being raised.