US3981009A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Bernoulli-DeMoivre sliding window friend-accept decider
Assignee: United States Department of the Navy
•
Filing: 1975-09-26
•
Granted: 1976-09-14
•
Expires: 1995-09-26
Abstract
Abstract A technique for making IFF Friend-Accept decisions based upon either receng T a correct replies in any consecutive sequence of W responses in a larger, predetermined number N of responses, or receiving a consecutive series of a predetermined number R a of correct replies. A Non-Accept indication is provided upon the occurrence of N interrogations before either T a correct replies are received in the group of W responses, or a consecutive series of R a correct replies are received. Target leading edge information is also derived from these determinations.
Inventors
- 👤 Walton B. Bishop
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 22:17
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/74; G01S13/76; G01S13/78
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
526 words
A Friend-Accept decision device for use in an IFF system which, on the basis of replies to interrogations, determines whether the replies appear to come from a friend or not, comprising: means for receiving replies to interrogations and for indicating when a reply is correct; means connected to said IFF system for counting the number of interrogations made by the IFF system; first means connected to said receiving means and to said counting means for producing a first accept signal when a predetermined number T a of correct replies are received in any consecutive sequence of W responses before no more than N interrogations have been sent; second means connected to said receiving means and to said counting means for producing a second accept signal when a predetermined run R a of consecutive correct replies are received before no more than N interrogations have been sent; logic means coupled to said first and second means for producing a Target Friend-Accept signal upon the occurrence of either said first accept signal or said second accept signal; third means connected to said receiving means and to said counting means for producing a first non-accept signal when N interrogations have been sent before a predetermined number T a of correct replies are received in a consecutive sequence of W responses; fourth means connected to said receiving means and to said counting means for producing a second non-accept signal when N interrogations have been sent before a run R a of consecutive correct replies are received; second logic means coupled to said third and fourth means for producing a target non-accept signal upon the joint occurrence of said first and second non-accept signals; fifth means connected to said receiving means and to said counting means for producing a first trailing edge alert-indication signal when a predetermined number T t of correct replies in a consecutive sequence of W responses are received after receiving a predetermined number T a of correct replies in a previous consecutive sequence of W responses; sixth means connected to said receiving means and to said counting means for producing a second trailing edge alert indication-signal when a predetermined number T t or less correct replies in a consecutive sequence of W responses are received after N interrogations have been sent; seventh means connected to said receiving means and to said counting means for producing a first signal when, before N interrogations have been sent a predetermined run of R a consecutive correct replies are received; eighth means connected to said receiving means and to said counting means for producing a second signal when, before N interrogations have been sent, a predetermined number T t of correct replies in a consecutive sequence of W responses are received; third logic means connected to said seventh and eighth means for producing a third alert-indication signal upon the occurrence of said second signal after occurrence of said first signal; and fourth logic means coupled to said fifth and sixth means and to said third logic means for producing a target trailing edge alert signal upon the occurrence of either of said first, second, or third trailing edge alert indication signal.
Claim 2
Dependent Claim
526 words
A Friend-Accept decision device for use in an IFF system which, on the basis of replies to interrogations, determines whether the replies appear to come from a friend or not, comprising: means for receiving replies to interrogations and for indicating when a reply is correct; means connected to said IFF system for counting the number of interrogations made by the IFF system; first means connected to said receiving means and to said counting means for producing a first accept signal when a predetermined number T a of correct replies are received in any consecutive sequence of W responses before no more than N interrogations have been sent; second means connected to said receiving means and to said counting means for producing a second accept signal when a predetermined run R a of consecutive correct replies are received before no more than N interrogations have been sent; logic means coupled to said first and second means for producing a Target Friend-Accept signal upon the occurrence of either said first accept signal or said second accept signal; third means connected to said receiving means and to said counting means for producing a first non-accept signal when N interrogations have been sent before a predetermined number T a of correct replies are received in a consecutive sequence of W responses; fourth means connected to said receiving means and to said counting means for producing a second non-accept signal when N interrogations have been sent before a run R a of consecutive correct replies are received; second logic means coupled to said third and fourth means for producing a target non-accept signal upon the joint occurrence of said first and second non-accept signals; fifth means connected to said receiving means and to said counting means for producing a first trailing edge alert-indication signal when a predetermined number T t of correct replies in a consecutive sequence of W responses are received after receiving a predetermined number T a of correct replies in a previous consecutive sequence of W responses; sixth means connected to said receiving means and to said counting means for producing a second trailing edge alert indication-signal when a predetermined number T t or less correct replies in a consecutive sequence of W responses are received after N interrogations have been sent; seventh means connected to said receiving means and to said counting means for producing a first signal when, before N interrogations have been sent a predetermined run of R a consecutive correct replies are received; eighth means connected to said receiving means and to said counting means for producing a second signal when, before N interrogations have been sent, a predetermined number T t of correct replies in a consecutive sequence of W responses are received; third logic means connected to said seventh and eighth means for producing a third alert-indication signal upon the occurrence of said second signal after occurrence of said first signal; and fourth logic means coupled to said fifth and sixth means and to said third logic means for producing a target trailing edge alert signal upon the occurrence of either of said first, second, or third trailing edge alert indication signal.
Claim 3
Dependent Claim
194 words
The Friend-Accept decider of claim 1 wherein said first, third, fifth, sixth, and eighth means further include: means connected to said receiving means for producing a sequence of information elements, each element corresponding to an interrogation and indicating whether the corresponding response was a correct reply or not; first means connected to said element producing means for storing a sequence of W of said elements; means connected to said storage means and to said element producing means for generating a first signal each time that the last produced element corresponds to a correct reply and the element produced W elements before corresponds to other than a correct reply; means connected to said storage means and to said element producing means for generating a second signal each time that the last produced element corresponds to other than a correct reply and the information element produced W elements before corresponds to a correct reply; and difference count means connected to said first and second signal generating means for accumulating a difference count of the number of said first signals minus the number of said second signals and for producing a signal indicative of the difference count.
Claim 4
Dependent Claim
257 words
The Friend-Accept decider of claim 2 wherein: said first means further includes means connected to said difference counting means and to said interrogation counting means for producing said first accept signal when said difference counting means indicates a predetermined count of T a before said interrogation counting means indicates a predetermined count of N; said third means further includes means connected to said difference counting means and to said interrogation counting means for producing said first non-accept signal when said interrogation counting means indicates a predetermined count of at least N before said difference counting means indicates a predetermined count of T a ; said fifth means further includes means connected to said difference counting means and to said interrogation counting means for producing said first trailing edge alert indication signal when said difference indicates a predetermined number T t after counting to an equal or larger predetermined number T a ; and said sixth means further includes means connected to said difference counting means and to said interrogation counting means for producing said second trailing edge alert indication signal when said difference counting means indicates a predetermined count of T t after said interrogation counting means indicates a predetermined count of at least N; said eighth means further includes means connected to said difference counting means and to said interrogation counting means for producing said second intermediate indication signal when said difference counting means indicates a predetermined count of T t or less before said interrogation counting means indicates a predetermined count of N or more.
Claim 5
Dependent Claim
197 words
The Friend-Accept decider of claim 1 wherein said second, fourth, and seventh means further include: means connected to said receiving means for producing a sequence of information elements, each element corresponding to an interrogation and indicating whether the corresponding response was a correct reply or not; second means connected to said element producing means for storing a sequence of a predetermined number R a of said elements; means connected to said storage means and to said element producing means for generating a first signal each time that the last produced element corresponds to a correct reply and the element produced R a elements before corresponds to other than a correct reply; means connected to said storage means and to said element producing means for generating a second signal each time that the last produced element corresponds to other than a correct reply element produced R a elements before corresponds to a correct reply; and second difference counting means connected to said first and second signal generating means for accumulating a difference count of the number of said first signals minus the number of said second signals, and for producing a signal indicative of said second difference count.
Claim 6
Dependent Claim
160 words
The Friend-Accept decider of claim 4 wherein: said second means further includes means connected to said second difference counting means and to said interrogation counting means for producing a second indication signal when said second difference counting means indicates a predetermined count of R a before said interrogation number counting means indicates a predetermined count of N; said fourth means further includes means connected to said second difference counting means and to said interrogation counting means for producing said second non-accept signal when said difference counting means indicates a predetermined count of R a after said interrogation counting means indicates a predetermined count of at least N; and said seventh means further includes means connected to said second difference counting means and to said interrogation counting means for producing said first intermediate indication signal when said second difference counting means indicates a predetermined count of R a before said interrogation counting means indicates a predetermined count of at least N.
Claim 7
Independent Claim
263 words
A method for determining whether replies to interrogations appear to come from a friend or an enemy comprising the steps of: counting the number of interrogations; counting the number of correct replies in a sequence W of last responses; counting the number of incorrect replies in a sequence W of last responses; subtracting the number of incorrect replies from the number of correct replies to produce a difference quantity T; indicating that the replies appear to come from a friend if the difference quantity T becomes equal to or greater than a predetermined threshold T a before a predetermined number N or interrogations are counted; counting the number of consecutive correct replies to accumulate a run-sum R; indicating that the replies appear to come from a friend if said run-sum reaches or exceeds a predetermined number R a before a predetermined number N or interrogations are counted; indicating that the replies do not appear to come from a friend if said predetermined number N or replies are counted before a friend indication occurs; and indicating that the responding signals constitute a trailing edge when said difference T is equal to or greater than a predetermined number T t before a predetermined number N or interrogations are counted; or when said difference T is equal to T t after being at a greater predetermined number T a ; or when said run-sum reaches or exceeds a predetermined number R a and said difference T is equal to or less than a predetermined number T t before a predetermined number N or interrogations are counted.
Claim 8
Independent Claim
263 words
A method for determining whether replies to interrogations appear to come from a friend or an enemy comprising the steps of: counting the number of interrogations; counting the number of correct replies in a sequence W of last responses; counting the number of incorrect replies in a sequence W of last responses; subtracting the number of incorrect replies from the number of correct replies to produce a difference quantity T; indicating that the replies appear to come from a friend if the difference quantity T becomes equal to or greater than a predetermined threshold T a before a predetermined number N or interrogations are counted; counting the number of consecutive correct replies to accumulate a run-sum R; indicating that the replies appear to come from a friend if said run-sum reaches or exceeds a predetermined number R a before a predetermined number N or interrogations are counted; indicating that the replies do not appear to come from a friend if said predetermined number N or replies are counted before a friend indication occurs; and indicating that the responding signals constitute a trailing edge when said difference T is equal to or greater than a predetermined number T t before a predetermined number N or interrogations are counted; or when said difference T is equal to T t after being at a greater predetermined number T a ; or when said run-sum reaches or exceeds a predetermined number R a and said difference T is equal to or less than a predetermined number T t before a predetermined number N or interrogations are counted.
References Cited (Backward Citations)
US3781881A
Cited
US3922673A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-09-14 | 1980-03-15 | 1980-09-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-09-14 | 1984-03-15 | 1984-09-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-09-14 | 1988-03-15 | 1988-09-14 | $7700.00 | Window Closed / Lapsed |