US4198632A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Transponder reply limiting by means of recognition of fixed interrogation periods
Assignee: United States Department of the Navy
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Filing: 1971-06-10
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Granted: 1980-04-15
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Expires: 1991-06-10
Abstract
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.
Inventors
- 👤 Walton B. Bishop
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 22:24
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/74; G01S13/76; G01S13/767
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
137 words
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.
Claim 2
Dependent Claim
137 words
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.
Claim 3
Dependent Claim
30 words
Apparatus as recited in claim 1 wherein said inhibiting means comprises at least one monostable multivibrator and a plurality of AND gates for supplying inhibiting pulses to said recognition means.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-04-15 | 1983-10-15 | 1984-04-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-04-15 | 1987-10-15 | 1988-04-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-04-15 | 1991-10-15 | 1992-04-15 | $7700.00 | Window Closed / Lapsed |