Transponder reply limiting by means of recognition of fixed interrogation periods
First Claim
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1. In a transponder receiving IFF interrogation signals, apparatus for supplying an adequate number of responses to each IFF interrogator having a fixed interrogation frequency comprising:
- means for recognizing periodic signals of an interrogator including,delay means,a first AND gate coupled to said delay means,counter means coupled to said first AND gate adapted to produce an output pulse upon counting a predetermined number of periodic signals;
means for responding to said interrogator upon the deletion of said periodic interrogation signals, said responding means including means for producing a pulse having a length corresponding to said adequate number of transponder responses and a second AND gate coupled to said pulse producing means and said first AND gate; and
,means for inhibiting responses to said interrogator after an adequate number of replies have been given to said interrogator.
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Abstract
It is shown that the interrogation repetition period (IRP) of an interrogr can be recognized by a transponder and then used by it to both determine when the interrogator has elicited a predetermined number of replies called an adequate response and limit the interrogator to that number during each scan. This form of reply limiting by a transponder requires absolutely no change in the type of signals transmitted. Logic circuits that perform the required functions are provided.
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2 Claims
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1. In a transponder receiving IFF interrogation signals, apparatus for supplying an adequate number of responses to each IFF interrogator having a fixed interrogation frequency comprising:
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means for recognizing periodic signals of an interrogator including, delay means, a first AND gate coupled to said delay means, counter means coupled to said first AND gate adapted to produce an output pulse upon counting a predetermined number of periodic signals; means for responding to said interrogator upon the deletion of said periodic interrogation signals, said responding means including means for producing a pulse having a length corresponding to said adequate number of transponder responses and a second AND gate coupled to said pulse producing means and said first AND gate; and
,means for inhibiting responses to said interrogator after an adequate number of replies have been given to said interrogator. - View Dependent Claims (2)
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Specification
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Current Assigneethe united states of america as represented by the secretary of the navy
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Original Assigneethe united states of america as represented by the secretary of the navy
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InventorsBishop, Walton B.
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Primary Examiner(s)Tubbesing, T. H.
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Application NumberUS03/151,973Time in Patent Office3,232 DaysField of Search343/6.8 LC, 343/6.8 RUS Class Current342/45CPC Class CodesG01S 13/767 Responders; Transponders te...
