US4435850A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Secure fiber optic data transmission system
Assignee: U S Holding Co Inc
•
Filing: 1982-02-16
•
Granted: 1984-03-06
•
Expires: 2002-02-16
Abstract
Abstract A fiber optic data transmission system is protected against external physical intrusion by obscuring the data in the natural quantum noise and then limiting access to the intruder by means of an optical power alarm. This is accomplished by modulating the data on a very large predetermined average optical power with a very small modulation index and then providing an alarm arrangement which is responsive to the received optical energy to activate an alarm means and to deactivate its associated transmitting arrangement when the received optical energy has an amplitude outside of a given amplitude region.
Inventors
- 👤 James H. Bowen
- 👤 David L. Baldwin
- 👤 Philip R. Couch
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 15:08
CPC Classifications
H; H04; H04B; H04B10/00; H04B10/80; H04B10/85; H04L; H04L7/00; H04L7/04; H04L7/06; H04L7/065
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
163 words
A secure fiber optic data transmission system comprising: an optical fiber means to provide two way optical communication between two spaced terminals; each of said two terminals including first means coupled to an adjacent end of said optical fiber means to receive optical energy modulated by data transmitted from the other of said two terminals; second means coupled to said adjacent end of said optical fiber means to transmit modulated optical energy to said other of said two terminals, said transmitted optical energy having a predetermined average optical power and data modulated thereon with a modulation index; and third means coupled to said first and second means resonsive to said received optical energy to activate an alarm means and to deactivate said second means when said received optical energy has an amplitude outside of a given amplitude region, said third means including a threshold comparator coupled to said first and second means having two spaced threshold values to define said given amplitude region.
Claim 2
Dependent Claim
163 words
A secure fiber optic data transmission system comprising: an optical fiber means to provide two way optical communication between two spaced terminals; each of said two terminals including first means coupled to an adjacent end of said optical fiber means to receive optical energy modulated by data transmitted from the other of said two terminals; second means coupled to said adjacent end of said optical fiber means to transmit modulated optical energy to said other of said two terminals, said transmitted optical energy having a predetermined average optical power and data modulated thereon with a modulation index; and third means coupled to said first and second means resonsive to said received optical energy to activate an alarm means and to deactivate said second means when said received optical energy has an amplitude outside of a given amplitude region, said third means including a threshold comparator coupled to said first and second means having two spaced threshold values to define said given amplitude region.
Claim 3
Dependent Claim
12 words
A system according to claim 1, wherein said data is analog data.
Claim 4
Dependent Claim
12 words
A system according to claim 1, wherein said data is binary data.
Claim 5
Dependent Claim
21 words
A system according to claim 3, wherein said binary data is represented by two different frequencies according to frequency shift techniques.
Claim 6
Independent Claim
43 words
A system according to claims 1, 2, 3, or 4, wherein said modulation index is just high enough to ensure an adequate signal to noise ratio at said first means to enable recovery of said data from said received data modulated optical energy.
Claim 7
Dependent Claim
14 words
A system according to claim 1, wherein said alarm means includes a visual alarm.
Claim 8
Dependent Claim
15 words
A system according to claim 2, wherein said alarm means further includes a visual alarm.
Claim 9
Dependent Claim
14 words
A system according to claim 3, wherein said alarm means includes a visual alarm.
Claim 10
Dependent Claim
14 words
A system according to claim 5, wherein said alarm means includes an audible alarm.
Claim 11
Dependent Claim
15 words
A system according to claim 9, wherein said alarm means further includes a visual alarm.
Claim 12
Dependent Claim
14 words
A system according to claim 5, wherein said alarm means includes a visual alarm.
Claim 13
Independent Claim
18 words
A system according to claims 1, 2, 3, or 4, wherein said alarm means includes an audible alarm.
Claim 14
Dependent Claim
15 words
A system according to claim 12, wherein said alarm means further includes a visual alarm.
Claim 15
Dependent Claim
14 words
A system according to claim 4, wherein said alarm means includes a visual alarm.
References Cited (Backward Citations)
US4217488A
Cited
US4292628A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-03-06 | 1987-09-05 | 1988-03-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-03-06 | 1991-09-05 | 1992-03-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-03-06 | 1995-09-05 | 1996-03-06 | $7700.00 | Window Closed / Lapsed |