REFLECTED IFF INTERROGATION REJECTOR

• US 3,646,556 A
• Filed: 03/25/1970
• Issued: 02/29/1972
• Est. Priority Date: 03/25/1970
• Status: Expired due to Term

• Current Assignee: Walton B. Bishop
• Original Assignee: Walton B. Bishop
• Inventors: Bishop, Walton B.
• Primary Examiner(s): Tubbesing, T. H.
• Application Number:
  US05/022,467
• Time in Patent Office: 706 Days
• Field of Search: 343/6.5,114.5
• US Class Current: 342/45
• CPC Class Codes: G01S 13/762 with special measures concerning the radiation pattern, e.g. S.L.S. aerials or aerial systems providing at least two radiation patterns, e.g. providing sum and difference patterns, H01Q25/00

Abstract

A technique of using the time between the direct path and the reflected path of an IFF interrogation to inhibit responses to succeeding reflected path interrogations.

Claims

1. In a transponder receiving IFF interrogation signals and emitting reply signals, a suppression network for suppressing reply signals for reflected interrogation signals comprising:

means for determining the time interval between said reflected interrogation signal and a direct interrogation signal;

storage means for storing said determined time interval; and

means for suppressing ensuing transponder reply signals time separated from a reply signal for a previous interrogation by said stored time interval.

2. A suppression network as recited in claim 1, wherein means are included to reset said switch when said counter reaches a means, a free running pulse generator and a switch, wherein a first reply signal sets the switch to produce a continuous output to one input of said coincidence means, the other input of said coincidence means being supplied by said pulse generator, the output signal of said coincidence means initiating said counter, a second reply signal transferring the count in said counter at that instant into said storage means.

3. A suppression network as recited in claim 2 wherein said counter resets said switch upon reaching a predetermined count whereby there is no output signal by said coincidence means.

4. A suppression network as recited in claim 3 wherein said suppressing means comprises:

means for delaying each reply signal; and

coincidence means for receiving said delayed reply signal and an indicating signal from said stored means, said coincidence means suppressing a reply signal if said indicating signal indicates that said reply signal is separated from a reply signal for a previous interrogation by a determined time interval stored in said storage means.

5. A suppression network as recited in claim 4 wherein said storage means comprises:

delay means for delaying a first count signal a predetermined time;

coincidence means for receiving said delayed count signal and an ensuing identical count signal, said coincidence means output suppressing said coincidence means receiving said delayed reply signal.