Secondary surveillance radar system, ground equipment for use therein, and response signal checking method applied thereto

A secondary surveillance radar system including a ground equipment which reliably surveils an airspace under surveillance, even when an aircraft including a mode S transponder and an aircraft including an ATCRBS transponder are both located in the airspace,

• wherein the ground equipment comprising:
• a transmitter configured to transmit a interrogation signal to the airspace;
• a receiver configured to receive a reply signal to the interrogation signal transmitted by the transmitter;
• a correlation processor configured to specify a mode S reply signal transmitted from the aircraft including the mode S transponder based on correlations between mode S reply signals of reply signals each of which is received by the receiver and all-call interrogation signals each of which is transmitted each time one sweep is carried out;
• and
• a determination processor configured to determine whether each of mode S reply signals respectively specified as mode S reply signals transmitted from a plurality of aircrafts is valid or invalid, based on a variance between a plurality of range data each obtained in units of one sweep with respect to an associated one of the plurality of aircrafts,
• wherein in units of one all-call time period, the transmitter varies both of a time interval between time when transmission of an all-call interrogation signal specific for mode S is completed and time when transmission of an all-call interrogation signal specific for mode A is started and a time interval between time when the transmission of the all-call interrogation signal specific for mode S is completed and time when transmission of an all-call interrogation signal specific for mode C is started.

A secondary surveillance radar system including a ground equipment which reliably surveils an airspace under surveillance, even when an aircraft including a mode S transponder and an aircraft including an ATCRBS transponder are both located in the airspace,

• wherein the ground equipment comprising:
• a transmitter configured to transmit a interrogation signal to the airspace;
• a receiver configured to receive a reply signal to the interrogation signal transmitted by the transmitter;
• a correlation processor configured to specify a mode S reply signal transmitted from the aircraft including the mode S transponder based on correlations between mode S reply signals of reply signals each of which is received by the receiver and all-call interrogation signals each of which is transmitted each time one sweep is carried out;
• and
• a determination processor configured to determine whether each of mode S reply signals respectively specified as mode S reply signals transmitted from a plurality of aircrafts is valid or invalid, based on a variance between a plurality of range data each obtained in units of one sweep with respect to an associated one of the plurality of aircrafts,
• wherein in units of one all-call time period, the transmitter varies both of a time interval between a sync phase reversal of an all-call interrogation signal specific for mode S and a pulse P3 of an all-call interrogation signal specific for mode A and a time interval between the sync phase reversal of the all-call interrogation signal specific for mode S and a pulse P3 in an all-call interrogation signal specific for mode C.

A ground equipment for use in a secondary surveillance radar system, which reliably surveils an airspace under surveillance even when an aircraft including a mode S transponder and an aircraft including an ATCRBS transponder are located in the airspace, the ground equipment comprising:

• a transmitter configured to transmit a interrogation signal to the airspace;
• a receiver configured to receive a reply signal to the interrogation signal transmitted by the transmitter;
• a correlation processor configured to specify an ATCRBS reply signal transmitted from the aircraft including the ATCRBS transponder based on correlations between ATCRBS reply signals of reply signals each of which is received by the receiver and all-call interrogation signals for mode A or mode C each of which is transmitted each time one sweep is carried out;
• and
• a determination processor configured to determine whether each of ATCRBS reply signals respectively specified as ATCRBS reply signals transmitted from a plurality of aircrafts is valid or invalid, based on a variance between a plurality of range data each obtained in units of one sweep with respect to an associated one of the plurality of aircrafts,
• wherein in units of one all-call time period, the transmitter varies both of a time interval between time when transmission of an all-call interrogation signal specific for mode S is completed and time when transmission of an all-call interrogation signal specific for mode A is started and a time interval between the transmission of the all-call interrogation signal specific for mode S is completed and time when transmission of an all-call interrogation signal specific for mode C is started.

A ground equipment for use in a secondary surveillance radar system, which reliably surveils an airspace under surveillance even when an aircraft including a mode S transponder and an aircraft including an ATCRBS transponder are both located in the airspace, the ground equipment comprising:

• a transmitter configured to transmit a interrogation signal to the airspace;
• a receiver configured to receive a reply signal to the interrogation signal transmitted by the transmitter;
• a correlation processor configured to specify an ATCRBS reply signal transmitted from the aircraft including the ATCRBS transponder based on correlations between ATCRBS reply signals of reply signals each of which is received by the receiver and all-call interrogation signals for mode A or mode C each of which is transmitted each time one sweep is carried out;
• and
• a determination processor configured to determine whether each of ATCRBS reply signals respectively specified as ATCRBS reply signals transmitted from a plurality of aircrafts is valid or invalid, based on a variance between a plurality of range data each obtained in units of one sweep with respect to an associated one of the plurality of aircrafts,
• wherein in units of one all-call time period, the transmitter varies both of a time interval between a sync phase reversal of an all-call interrogation signal specific for mode S and a pulse P3 in an all-call interrogation signal specific for mode A and a time interval between the sync phase reversal of the all-call interrogation signal specific for mode S and a pulse P3 of an all-call interrogation signal specific for mode C.

A reply-signal checking method for checking validity of a reply signal to a interrogation signal in an airspace under surveillance, which enables the airspace to be reliably surveilled even when an aircraft including a mode S transponder and an aircraft including an ATCRBS transponder are both located in the airspace, the reply-signal checking method comprising:

• transmitting a interrogation signal to the airspace;
• receiving a reply signal to the transmitted interrogation signal;
• specifying an ATCRBS reply signal transmitted from the aircraft including the ATCRBS transponder based on correlations between ATCRBS reply signals of received reply signals and all-call interrogation signals for mode A or mode C each of which is transmitted each time one sweep is carried out;
• and
• determining whether each of ATCRBS reply signals respectively specified as ATCRBS reply signals transmitted from a plurality of aircrafts is valid or invalid, based on a variance between a plurality of range data each obtained in units of one sweep with respect to an associated one of the plurality of aircrafts,
• wherein the transmitting the interrogation signal including varying, in units of one all-call time period, both of a time interval between time when transmission of an all-call interrogation signal specific for mode S is completed and time when transmission of an all-call interrogation signal specific for mode A is started and a time interval between the transmission of the all-call interrogation signal specific for mode S is completed and time when transmission of an all-call interrogation signal specific for mode C is started.

A reply-signal checking method for checking validity of a reply signal to a interrogation signal in an airspace under surveillance, in which enables the airspace to be reliably surveilled even when an aircraft including a mode S transponder and an aircraft including an ATCRBS transponder are both located in the airspace, the reply-signal checking method comprising:

• transmitting a interrogation signal to the airspace;
• receiving a reply signal to the transmitted interrogation signal;
• specifying an ATCRBS reply signal transmitted from the aircraft including the ATCRBS transponder based on correlations between ATCRBS reply signals of received reply signals and all-call interrogation signals for mode A or mode C each of which is transmitted each time one sweep is carried out;
• and
• determining whether each of ATCRBS reply signals respectively specified as ATCRBS reply signals transmitted from a plurality of aircrafts is valid or invalid, based on a variance between a plurality of range data each obtained in units of one sweep with respect to an associated one of the plurality of aircrafts,
• wherein the transmitting the interrogation signal including varying, in units of one all-call time period, both of a time interval between a sync phase reversal of an all-call interrogation signal specific for mode S and time when a pulse P3 of an all-call interrogation signal specific for mode A and a time interval between the sync phase reversal of the all-call interrogation signal specific for mode S and a pulse P3 of an all-call interrogation signal specific for mode C.