EP0337644A1
Expired / Lapsed
EP
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Method and apparatus for transmitting information
Assignee: British Telecommunications PLC
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Filing: 1989-04-04
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Granted: —
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Expires: 2009-04-04
Abstract
Abstract A method and apparatus for transmitting information comprises a signal generator (1) for continuously generating a pair of optical signals (f₁, f₂). These signals are similarly modulated in a modulator (5) with information to be transmitted and are combined with their polarisations substantially orthogonal. The combined signals are transmitted with the portions of each signal modulated with the same information being transmitted together down an optical fibre.
Inventors
- 👤 Terence Geoffrey Hodgkinson
- 👤 Andrew Robert John Cook
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 05:58
CPC Classifications
H; H04; H04B; H04B10/00; H04B10/25; H04B14/00; H04B14/002; H04B14/008
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
33 words
A method of transmitting information, the method comprising continuously generating a pair of orthogonally polarised signals having different frequencies, modulating each signal similarly and transmitting the modulated signals together down an optical fibre.
Claim 2
Independent Claim
33 words
A method of transmitting information, the method comprising continuously generating a pair of orthogonally polarised signals having different frequencies, modulating each signal similarly and transmitting the modulated signals together down an optical fibre.
Claim 3
Dependent Claim
41 words
A method according to claim 1, wherein the generating step comprises generating signals with two frequencies, the two signals with the polarisation of one signal orthogonal to the other, and modulating the signals in accordance with the information to be transmitted.
Claim 4
Dependent Claim
14 words
A method according to claim 2, wherein the signals are modulated after being combined.
Claim 5
Dependent Claim
53 words
A method according to claim 1, wherein the generating step comprises generating two carrier signals with different frequencies, coupling the two signals together, modulating the coupled signals, and feeding the modulated, coupled signals to a birefringent device which imparts the orthogonal polarisations on the two modulated carrier signals in response to their frequencies.
Claim 6
Dependent Claim
41 words
A method according to claim 1, wherein the generating step comprises generating a single carrier signal; modulating the carrier signal in accordance with the information to be transmitted; and generating the two orthogonally polarised and frequency shifted versions of the carrier.
Claim 7
Dependent Claim
58 words
A method according to claim 5, wherein the orthogonally polarised signals are generated by generating two versions of the modulated carrier signal, shifting the frequency of one of the two version relative to the other, adjusting the polarisation of the signals to be orthogonal to each other and combining the orthogonally polarised versions of the modulated carrier signal.
Claim 8
Independent Claim
59 words
A method of transmitting a signal comprising a number of frequency multiplexed channels, the method comprising generating a second version of the multiplex signal having frequencies different from those of the multiplex signal; and transmitting the two versions of the signal with orthogonal polarisations and with the portions of each signal corresponding to the same channel being transmitted together.
Claim 9
Independent Claim
59 words
A method of transmitting a signal comprising a number of frequency multiplexed channels, the method comprising generating a second version of the multiplex signal having frequencies different from those of the multiplex signal; and transmitting the two versions of the signal with orthogonal polarisations and with the portions of each signal corresponding to the same channel being transmitted together.
Claim 10
Dependent Claim
54 words
Apparatus for transmitting information, the apparatus comprising signal generating means for generating a pair of orthogonally polarised signals having different frequencies anda being modulated in accordance with the information to be transmitted; and transmitting means for transmitting the modulated signals with the portions of each signal modulated with the same information being transmitted together.
Claim 11
Dependent Claim
54 words
Apparatus for transmitting information, the apparatus comprising signal generating means for generating a pair of orthogonally polarised signals having different frequencies anda being modulated in accordance with the information to be transmitted; and transmitting means for transmitting the modulated signals with the portions of each signal modulated with the same information being transmitted together.
Claim 12
Dependent Claim
53 words
Apparatus according to claim 8, wherein the signal generating means comprises carrier signal generating means for generating signals with two frequencies, combining means for combining the two signals with the polarisation of one signal orthogonal to the other, and modulating means for modulating the signals in accordance with the information to be transmitted.
Claim 13
Dependent Claim
16 words
Apparatus according to claim 9, wherein the modulating means is positioned downstream of the combining means.
Claim 14
Dependent Claim
65 words
Apparatus according to claim 8, wherein the signal generating means comprises carrier signal generating means for generating two carrier signals with different frequencies, signal coupling means for coupling the two signals, the coupled signals being fed to the modulating means, and a birefringent device downstream of the modulating means for imparting the orthogonal polarisations on the two modulated carrier signals in response to their frequencies.
Claim 15
Dependent Claim
53 words
Apparatus according to claim 8, wherein the signal generating means comprises a carrier signal generating means for generating a single carrier signal; modulating means for modulating the carrier signal in accordance with the information to be transmitted; and means for generating the two orthogonally polarised and frequency shifted versions of the carrier signal.
Claim 16
Dependent Claim
70 words
Apparatus according to claim 12, wherein the means for generating the orthogonally polarised signals comprises a signal splitter for generating two versions of the modulated carrier signal, frequency shifting means for shifting the frequency of one of the two versions, polarisation control means for adjusting the polarisation of the signals to be orthogonal to each other, and combining means for combining the orthogonally polarised versions of the modulated carrier signal.
Claim 17
Dependent Claim
25 words
Apparatus according to any of claims 8 to 13, wherein the modulating means is separate from the means for generating the carrier signal or signals.
Claim 18
Dependent Claim
28 words
Apparatus according to any of claims 8 to 14, wherein the modulating means modulates the carrier signal or signals in accordance with an ASK, FSK, or PSK system.
Claim 19
Dependent Claim
62 words
Apparatus for transmitting a signal, the apparatus comprising a number of frequency multiplexed channels comprises means for generating a second version of the multiplex signal having frequencies different from those of the multiplex signal; and means for transmitting the two versions of the signal with orthogonal polarisations and with the portions of each signal corresponding to the same channel being transmitted together.
Claim 20
Dependent Claim
62 words
Apparatus for transmitting a signal, the apparatus comprising a number of frequency multiplexed channels comprises means for generating a second version of the multiplex signal having frequencies different from those of the multiplex signal; and means for transmitting the two versions of the signal with orthogonal polarisations and with the portions of each signal corresponding to the same channel being transmitted together.
References Cited (Backward Citations)
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