IFF interrogator identification system

• US 3,922,673 A
• Filed: 05/31/1974
• Issued: 11/25/1975
• Est. Priority Date: 05/31/1974
• 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:
  US05/474,992
• Time in Patent Office: 543 Days
• Field of Search: 343/6.5LC
• US Class Current: 342/45
• CPC Class Codes: G01S 13/782 using multimoding or selective addressing

Abstract

An IFF system with the capability of determining the identity of the interrogator and of conditioning the reply based upon the identity code of the interrogator. Identity of the interrogator contained in a received interrogation signal is determined by logic devices in order to determine presence of pulses in predetermined positions of the signal.

Claims

1. In a transponder having a shift register for receiving an interrogation signal and means for detecting the presence of mode-command pulses in said signal, the improvement comprising:

first coincidence means connected to said shift register for detecting the presence of an identity-code trigger pulse in said interrogation signal and for producing a first signal upon occurence of said detection;

output means connected to said first coincidence means responsive to said first signal whereby an output signal will be present only upon occurence of said first signal;

second coincidence means connected to said shift register for detecting the presence of identity-code pulses in said interrogation signal and for producing output signals corresponding to the presence of said detected pulses.

2. In a transponder for receiving an IFF interrogation signal transmitting a reply signal, said interrogation signal comprising pulses which, if present, occur in any of equally spaced pulse positions, said pulse positions constituting an initial pulse position, an identity-code trigger-pulse position, and a series of identity-code pulse positions, the addition of:

an identity determining response network for determining the identity of the interrogating source when said source is transmitting said identity, and for providing signals indicating The presence or absence of such identity-code, said identity determining response network comprising;

delay means for sequentially storing said interrogation signal;

first coincidence means connected to said delay means for detecting the presence in said delay means of said initial pulse and said identity-code trigger pulse and for producing a first signal upon occurrence of said detection; and

, second coincidence means connected to said delay means for detecting the presence of any of said identity-code pulses and for producing output signals corresponding to each of last said detected pulses connected to said delay means.

3. In a transponder for receiving an IFF interrogation signal and for transmitting a reply signal, said interrogation signal comprising pulses which if present occur in any of equally spaced pulse positions, said pulse positions constituting an initial pulse position, an identity-code trigger pulse position, and a series of identity-code pulse positions, the addition of:

an identity determining response network for determining the identity of the interrogating source when said source is transmitting said identity, and for providing signals indicating the presence or absence of such identity-code, said identity determining response network comprising;

delay means for sequentially storing said interrogation signal;

first coincidence means connected to said delay means for detecting the presence in said delay means of said initial pulse and said identity-code trigger pulse and for producing a first signal upon occurrence of said detection;

first timing means connected to said first coincidence means for producing a timed signal upon occurrence of said first signal, said timed signal having a duration equal to the time necessary for said delay means to receive the entire interrogation signal;

second coincidence means connected to said delay means for detecting the presence in said delay means of any of said command pulses and for producing second signal corresponding to each detected command pulse;

first output means connected to said second coincidence means and to said first timing means for producing first output signals corresponding to the joint occurrence of said second signals and said timed signal;

second output means connected to said second coincidence means and to said first timing means for producing second output signals corresponding to the occurrence of said second signals and to the non-occurrence of said timed signal;

third coincidence means connected to said delay means for producing a third signal upon determining that only said initial pulse and all said identity-code pulse positions of said interrogation signal have been received into said delay means, and that said initial first and said trigger pulses are present; and

fourth coincidence means connected to said delay means and to said third coincidence means for detecting the presence of any of said identity-code pulses, and for producing output signals corresponding to each of last said detected pulses.

4. The transponder of claim 3 wherein said coincidence means and said output means are comprised of AND gates.

5. The transponder of claim 3 wherein said delay means is a shift register.

6. The transponder of claim 5 wherein said first coincidence means is connected to the first and fifth bins of said shift register and wherein said trigger pulse occurs in the fifth pulse position.

7. The transponder of claim 5 wherein said third coincidence means is connected to the first eleven bins excluding the ninth bin, of said shift register and wherein all identity-code pulse positions are contained within the first sixteen pulses of said interrogation signal.