Device and method for SPR detection in a Mode-S transponder
First Claim
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1. In a Mode-S transponder, a subsystem for detecting synchronization signals, comprising:
- a receiver for receiving a transponder signal containing at least a first pulse containing a transponder data segment having an synchronization signal; and
a phase detector for detecting a state change between first and second states, said state change corresponding to a change in phase of said transponder signal, said phase detector including a qualifier for determining whether, following said state change, said transponder signal remains at one of said first and second states for at least a predetermined minimum time.
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Abstract
A Mode-S transponder is provided for detecting synchronization phase reversal (SPR) signals. The transponder includes a receiver for receiving a Mode-S signal that contains a P6 pulse having a Mode-S data segment and an SPR signal therein. The transponder also includes a phase detector that detects a phase change between first and second states in the received Mode-S signal. The phase detector includes an SPR qualifier that determine whether, following a state change, the Mode-S signal remains at one of the first and second states for at least a predetermined minimum time sufficient to qualify as a detector enable signal.
34 Citations
20 Claims
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1. In a Mode-S transponder, a subsystem for detecting synchronization signals, comprising:
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a receiver for receiving a transponder signal containing at least a first pulse containing a transponder data segment having an synchronization signal; and a phase detector for detecting a state change between first and second states, said state change corresponding to a change in phase of said transponder signal, said phase detector including a qualifier for determining whether, following said state change, said transponder signal remains at one of said first and second states for at least a predetermined minimum time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A Mode-S transponder, comprising:
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a receiver for receiving air traffic communications signals from an Air Traffic Control Radar Beacon System (ATCRBS); a demodulator for demodulating said air traffic communications signals and outputting a data segment formatted in accordance with a predefined mode of communications; and a detection module for validating a synchronization pulse embedded within said data segment based in part upon a length of said synchronization pulse. - View Dependent Claims (13, 14, 15)
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16. A subsystem for controlling reply of a transponder to Mode-S interrogation signals, comprising:
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an input for receiving Mode-S signals containing a reference pulse and a P6 pulse, each of said P6 pulses containing a sink phase reversal (SPR) signal followed by a data segment containing Mode-S data, said reference and P6 pulses being separated in time by a pulse separation time and differing in amplitude from one another by a pulse amplitude difference; means for comparing at least one of said pulse amplitude difference and said pulse separation time with an amplitude difference threshold and a separation time threshold, respectively; means for setting at least one of said amplitude difference threshold and said separation time threshold such that said SPR signal is correctly identified in at least 95% of said received Mode-S signals in which said amplitude of said P6 pulse is at least 12 dB greater than said amplitude of said reference pulse; and an output for producing a reply to Mode-S signals for which said SPR signal is correctly identified. - View Dependent Claims (17, 18, 19, 20)
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Specification