US4002896A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Telecommunication system
Assignee: National Research Development Corporation
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Filing: 1975-01-21
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Granted: 1977-01-11
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Expires: 1995-01-21
Abstract
Abstract In a telecommunications system employing modulated optical signals, a highway is formed from optical fibres and a source of coherent light or other electromagnetic radiation of an adjacent frequency band is connected to one end of the highway. One or more modulators are connected to the highway at intermediate positions along its length, the or each modulator being arranged to periodically vary the optical path length of the highway. A demodulator is connected to the other end of the highway.
Inventors
- 👤 David Evan Naunton Davies
- 👤 Stuart Alexander Kingsley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 23:22
CPC Classifications
H; H04; H04B; H04B10/00; H04B10/50; H04B10/501; H04B10/503; H04B10/505; H04B10/5051
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
152 words
A telecommunications system comprising a highway formed from an optical fibre, a source of coherent electromagnetic radiation of optical frequency connected to one end of the highway via a Bragg cell responsive to an oscillator, a modulator comprising means for periodically varying the optical path length of the highway located at an intermediate position on the highway, an optical delay line of path length differing from that of the highway by less than the coherence time of the source of electromagnetic radiation, connected to the source of electromagnetic radiation and a demodulator responsive to said highway and said delay line comprising a photodetector and F.M. receiver having intermediate frequency equal to that of the oscillator supplying the Bragg cell, there being provided means for adjusting the plane of polarisation of the beam from said highway and said delay line so that both beams have the same plane of polaristation at the photo-detector.
Claim 2
Dependent Claim
152 words
A telecommunications system comprising a highway formed from an optical fibre, a source of coherent electromagnetic radiation of optical frequency connected to one end of the highway via a Bragg cell responsive to an oscillator, a modulator comprising means for periodically varying the optical path length of the highway located at an intermediate position on the highway, an optical delay line of path length differing from that of the highway by less than the coherence time of the source of electromagnetic radiation, connected to the source of electromagnetic radiation and a demodulator responsive to said highway and said delay line comprising a photodetector and F.M. receiver having intermediate frequency equal to that of the oscillator supplying the Bragg cell, there being provided means for adjusting the plane of polarisation of the beam from said highway and said delay line so that both beams have the same plane of polaristation at the photo-detector.
Claim 3
Dependent Claim
29 words
A telecommunications system as claimed in claim 1, in which the delay line comprises an optical fibre of the same length as the highway and disposed in proximity thereto.
Claim 4
Dependent Claim
74 words
A telecommunications system comprising a highway formed from an optical fibre, a source of coherent electromagnetic radiation of optical frequency at one end of the highway, a modulator comprising a source of acoustic energy and a body of material having a high acoustic impedence adapted to focus acoustic waves on to the surface of the fibre at an intermediate position on the highway, and demodulating means connected to the other end of the highway.
Claim 5
Dependent Claim
74 words
A telecommunications system comprising a highway formed from an optical fibre, a source of coherent electromagnetic radiation of optical frequency at one end of the highway, a modulator comprising a source of acoustic energy and a body of material having a high acoustic impedence adapted to focus acoustic waves on to the surface of the fibre at an intermediate position on the highway, and demodulating means connected to the other end of the highway.
Claim 6
Dependent Claim
41 words
A telecommunications system as claimed in claim 3, in which the body of material having a high acoustic impedance is of elliptical cross-section with the fibre disposed at one focus and a source of acoustic energy disposed at the other focus.
Claim 7
Dependent Claim
54 words
A telecommunications system as claimed in claim 3, in which the body of material having a high acoustic impedence is of parabolic cross-section with the fibre disposed at the focus of the parabola and the source of acoustic energy is planar and is disposed in a plane perpendicular to the axis of the parabola.
Claim 8
Dependent Claim
62 words
A telecommunications system comprising a highway formed from an optical fibre, a source of coherent electromagnetic radiation of optical frequency at one end of the highway, a modulator comprising a cylinder of piezoelectric material round which the fibre is wrapped, said modulator being located at an intermediate position on the highway, and demodulating means connected to the other end of the highway.
Claim 9
Dependent Claim
62 words
A telecommunications system comprising a highway formed from an optical fibre, a source of coherent electromagnetic radiation of optical frequency at one end of the highway, a modulator comprising a cylinder of piezoelectric material round which the fibre is wrapped, said modulator being located at an intermediate position on the highway, and demodulating means connected to the other end of the highway.
Claim 10
Dependent Claim
44 words
A telecommunications system as claimed in claim 6, including a plurality of modulators spaced along the highway, each modulator having associated means for applying a respective distinct data signal to the highway either modulated on to a respective sub-carrier or at base band frequency.
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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) | 1980-01-11 | 1980-07-12 | 1981-01-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-01-11 | 1984-07-12 | 1985-01-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-01-11 | 1988-07-12 | 1989-01-11 | $7700.00 | Window Closed / Lapsed |