Beacon interrogator beamwidth control using sidelobe signal integration in transponders
First Claim
1. A method for inhibiting response to interrogation signals by certain transponders in a secondary radar system having a plurality of transponders and an interrogating radar, where the transponders whose responses are to be inhibited are locate outside of a zone of interest to the interrogating radar, comprising the steps of:
- transmitting a reference signal Pref by said interrogating radar, said Pref signal being transmitted into said zone of interest at a power level that exceeds the power level of said Pref signal in all regions of space outside said zone of interest;
transmitting a control signal I1 by said interrogating radar at a predetermined time after transmission of said Pref signal, said I1 signal being transmitted at a power level that exceeds the power level of said Pref signal in all regions of space outside said zone of interest but that is lower than the power level of said Pref signal within said zone of interest;
receiving and detecting said Pref signal at a transponder;
measuring the peak amplitude of said detected Pref signal;
establishing a minimum trigger level at a predetermined value below said measured peak amplitude of said detected Pref signal;
receiving and detecting said I1 signal at said transponder;
integrating with respect to time said detected I1 signal over the period of said detected I1 signal;
measuring the peak amplitude of said integrated I1 signal;
comparing said peak amplitude of said integrated I1 signal with said minimum triggering level; and
inhibiting a response by said transponder to an interrogation signal transmitted by said interrogating radarwhenever said peak amplitude of said integrated I1 signal is greater than said minimum triggering level.
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Accused Products
Abstract
A method for inhibiting responses by transponders to interrogation signals originating in the side lobes of an interrogating radar of a secondary radar system. The interrogating radar first transmits a reference signal with the highest power level of the reference signal being directed into a zone of interest to the interrogating radar. The interrogating radar then transmits a control signal having a higher power level than the reference signal in all regions of space except within the zone of interest. The control signal is of substantially longer duration than the reference signal. A transponder receives, detects and measures the peak amplitude of the reference signal and establishes a minimum trigger level (MTL) at a predetermined level below the reference signal peak. The control signal is received, detected and integrated. The peak amplitude of the integrated control signal is compared with the MTL. A transponder response is inhibited if the peak amplitude of the integrated control signal is greater than the MTL. The peak amplitude of the integrated control signal may be amplified before comparison with the MTL to increase the amount of synthetic beam sharpening provided by the method and the amount of synthetic beam sharpening provided may be controlled by the interrogating radar by delaying the start of transmission of the control signal.
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Citations
10 Claims
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1. A method for inhibiting response to interrogation signals by certain transponders in a secondary radar system having a plurality of transponders and an interrogating radar, where the transponders whose responses are to be inhibited are locate outside of a zone of interest to the interrogating radar, comprising the steps of:
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transmitting a reference signal Pref by said interrogating radar, said Pref signal being transmitted into said zone of interest at a power level that exceeds the power level of said Pref signal in all regions of space outside said zone of interest; transmitting a control signal I1 by said interrogating radar at a predetermined time after transmission of said Pref signal, said I1 signal being transmitted at a power level that exceeds the power level of said Pref signal in all regions of space outside said zone of interest but that is lower than the power level of said Pref signal within said zone of interest; receiving and detecting said Pref signal at a transponder; measuring the peak amplitude of said detected Pref signal; establishing a minimum trigger level at a predetermined value below said measured peak amplitude of said detected Pref signal; receiving and detecting said I1 signal at said transponder; integrating with respect to time said detected I1 signal over the period of said detected I1 signal;
measuring the peak amplitude of said integrated I1 signal;comparing said peak amplitude of said integrated I1 signal with said minimum triggering level; and inhibiting a response by said transponder to an interrogation signal transmitted by said interrogating radar whenever said peak amplitude of said integrated I1 signal is greater than said minimum triggering level. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for inhibiting response to interrogation signals by certain transponders in a secondary radar system having a plurality of transponders and an interrogating radar, where the transponders whose responses are to be inhibited are located outside of a zone of interest to the interrogating radar, comprising the steps of:
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transmitting a reference signal Pref by said interrogating radar, said Pref signal being transmitted into said zone of interest at a power level that exceeds the power level of said Pref signal in all regions of space outside said zone of interest; transmitting a first control signal I1 by said interrogating radar at a first predetermined time after transmission of said Pref signal, said I1 signal being transmitted at a power level that exceeds the power level of said Pref signal in all regions of space outside said zone of interest but that is lower than the power level of said Pref signal within said zone of interest; transmitting a second control signal I2 by said interrogating radar at a second predetermined time after transmission of said Pref signal, said I2 signal being transmitted at a power level that exceeds the power level of said Pref signal in all regions of space outside said zone of interest but that is lower than the power level of said Pref signal within said zone of interest; receiving and detecting said Pref signal at a transponder; measuring the peak amplitude of said detected Pref signal; establishing a minimum trigger level at a predetermined value below said measured peak amplitude of said detected Pref signal; receiving and detecting said I1 signal at said transponder; integrating with respect to time said detected I1 signal over the period of said detected I1 signal; receiving and detecting said I2 signal at said transponder; integrating with respect to time said detected I2 signal over the period of said detected I2 signal; measuring the peak amplitude of said integrated I2 signal; individually comparing said peak amplitudes of said integrated I1 signal and said integrated I2 signal with said minimum triggering level; and inhibiting a response by said transponder to an interrogation signal transmitted by said interrogating radar whenever said peak amplitude of either said integrated I1 signal or said integrated I2 signal is greater than said minimum triggering level. - View Dependent Claims (9, 10)
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Specification