US4241447A
Expired / Lapsed
US
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Secure spread spectrum communication system
Assignee: ITT Inc
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Filing: 1969-07-22
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Granted: 1980-12-23
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Expires: 1989-07-22
Abstract
Abstract A communication system is protected against jamming by modifying a conventional spread spectrum communication system by inserting errors, in the form of digital noise, into the pseudo-noise digital code used to generate the spread spectrum carrier. A bidirectional system is provided so that when jamming occurs, as a consequence of breaking the corrupted spread spectrum code, the pseudo-noise digital code and/or the percent of errors is changed in a prearranged manner to compensate for the jamming and/or reduce the likelihood of breaking the corrupted spread spectrum code. A conventional correlation receiver is employed to recover the intelligence.
Inventors
- 👤 Marvin A. Epstein
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:34
CPC Classifications
H; H04; H04K; H04K3/00; H04K3/20; H04K3/22; H04K3/224; H04K3/226; H04K3/25; H04K2203/00; H04K2203/30; H04K2203/36
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
82 words
Secure communication apparatus comprising: a first source of a given pseudo-noise digital code; first means coupled to said source to corrupt said given digital code by a predetermined percent of and distribution of errors; second means coupled to said first means to generate a spread spectrum signal in response to said corrupted given digital code; a second source of intelligence; and third means coupled to said second source and said second means to transmit said spread spectrum signal modulated by said intelligence.
Claim 2
Dependent Claim
82 words
Secure communication apparatus comprising: a first source of a given pseudo-noise digital code; first means coupled to said source to corrupt said given digital code by a predetermined percent of and distribution of errors; second means coupled to said first means to generate a spread spectrum signal in response to said corrupted given digital code; a second source of intelligence; and third means coupled to said second source and said second means to transmit said spread spectrum signal modulated by said intelligence.
Claim 3
Dependent Claim
20 words
Apparatus according to claim 1, further including a conventional correlation receiver coupled to said third means to recover said intelligence.
Claim 4
Dependent Claim
107 words
Apparatus according to claim 2, wherein said receiver further includes fourth means to monitor said recovery of said intelligence; said first source is adjustable to produce a plurality of different pseudo-noise digital codes in addition to said given digital code; said first means is adjustable to produce a plurality of different percents of and distributions of errors in additions to said predetermined percent of errors; and further including fifth means to enable the selection of a prearranged one of at least one of said plurality of digital codes and said plurality of percents of 2nd distributions of errors when said fourth means indicates that communication is lost.
Claim 5
Dependent Claim
33 words
Apparatus according to claim 1, wherein said first means includes a digital noise generator, and a binary combining means coupled to said first source and said generator to corrupt said given digital code.
Claim 6
Dependent Claim
50 words
Apparatus according to claim 4, wherein said noise generator includes a Gaussian noise generator, an adjustable direct current bias source, a summing means coupled to said Gaussian noise generator and said bias source, a level regenerator coupled to said summing means, and a sampling means coupled to said level regenerator.
Claim 7
Dependent Claim
14 words
Apparatus according to claim 5, wherein said Gaussian noise generator includes a gas tube.
Claim 8
Dependent Claim
13 words
Apparatus according to claim 5, wherein said level regenerator includes an amplitude limiter.
Claim 9
Dependent Claim
13 words
Apparatus according to claim 4, wherein said combining means includes a modulo-2 adder.
Claim 10
Dependent Claim
12 words
Apparatus according to claim 8, wherein said adder includes an EXCLUSIVE-OR gate.
Claim 11
Dependent Claim
54 words
Apparatus according to claim 4, wherein said noise generator includes a gas tube, an adjustable direct current bias source, a summing means coupled to said tube and said bias source, an amplitude limiter coupled to said summing means and a sampling means coupled to said limiter; and said adding means includes an EXCLUSIVE-OR gate.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-12-23 | 1984-06-23 | 1984-12-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-23 | 1988-06-23 | 1988-12-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-23 | 1992-06-23 | 1992-12-23 | $7700.00 | Window Closed / Lapsed |