Altitude coding for collision avoidance system
First Claim
1. An encoder for use at an interrogator station to provide an altitude address for transmission to a remote aircraft for reply thereto by the aircraft if the altitude of the remote aircraft corresponds to the address, comprising in combination;
- a. means for generating a pair of pulses having spacing between each pulse of said pair of pulses corresponding to a particular altitude address,b. means for periodically changing the spacing between said pair of pulses in accordance with a predetermined program to provide a scan of altitudes of predetermined bands, said pulse pair generating means including means for providing said spacing between said pulses in accordance with discrete changes in altitude of said interrogator station that occur during periods of transmission of said pulses, said discrete changes having a value greater than a predetermined value whereby said pulse pair spacing changes in discrete increments only with altitude changes exceeding said predetermined value.
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Accused Products
Abstract
In a cooperative collision avoidance system for aircraft, an altitude encoding system serves as a discriminant to insure orderly sequence of data exchange between cooperative aircraft, particularly, in a dense traffic environment. The system includes means for generating pairs of pulse-interval coded signals spaced to represent altitude addresses from interrogator to responder aircraft. Responder aircraft reply with a single pulse to such an altitude address only if the responder aircraft is at the altitude corresponding to the address.
19 Citations
8 Claims
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1. An encoder for use at an interrogator station to provide an altitude address for transmission to a remote aircraft for reply thereto by the aircraft if the altitude of the remote aircraft corresponds to the address, comprising in combination;
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a. means for generating a pair of pulses having spacing between each pulse of said pair of pulses corresponding to a particular altitude address, b. means for periodically changing the spacing between said pair of pulses in accordance with a predetermined program to provide a scan of altitudes of predetermined bands, said pulse pair generating means including means for providing said spacing between said pulses in accordance with discrete changes in altitude of said interrogator station that occur during periods of transmission of said pulses, said discrete changes having a value greater than a predetermined value whereby said pulse pair spacing changes in discrete increments only with altitude changes exceeding said predetermined value. - View Dependent Claims (2, 3, 4)
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5. A collision avoidance system for use with interrogator and responder aircraft wherein an altitude discriminant is provided in accordance with a predetermined altitude scan schedule comprising in combination:
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means on an interrogator aircraft for transmitting in accordance with a predetermined schedule of addressed altitudes a pair of probe pulses spaced in accordance with a fixed interval and a variable interval depending upon the barometric altitude of the interrogating aircraft, said pulse pair transmitting means including means for providing said spacing between said pulses in accordance with discrete changes in altitude of said interrogator aircraft that occur during periods of transmission of said pulses, said discrete altitude changes having a value greater than a predetermined value whereby said pulse pair spacing changes in discrete increments only with altitude changes exceeding said predetermined value, means on responder aircraft for receiving said pair of probe pulses, said receiving means including means for delaying said first received pulse of said pair of probe pulses an interval proportionate to the barometric altitude of the replying aircraft, and further means on said responding aircraft for transmitting a reply signal only if the second received pulse of said pair of probe pulses is received at a time substantially corresponding to the end of said delay of said first received pulse. - View Dependent Claims (6, 7, 8)
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Specification