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Patent EP0325281A2 successfully refreshed from Google Patents.
EP0325281A2
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EP
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Optical transmitter, optical receiver and optical transmission apparatus and control method of optical receiver
Assignee: Hitachi Ltd
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Filing: 1989-01-20
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Granted: —
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Expires: 2009-01-20
Abstract
Abstract A unipolar original electrical signal (1) is encoded by alternate mark inversion (2) and combined with a DC bias current (4) for injection of a semiconductor laser (7) to produce a bipolar FSK optical signal (8) that is transmitted to a receiver. At the receiver, the received signal (8) is coupled with optical local power (15) and fed to an optical/electrical transducer (18), preferably a semiconductor, to produce an electrical signal (19) that is demodulated to produce the original unipolar signal (27). The demodulator (28A) may be of different types, for example employing delaying part of the amplified electrical signal and mixing the delayed part with the original signal for passage of the combined signal through a low pass filter (24); with proper selection of the delay, an AMI decoder is not needed. The demodulator may also be of the type that has one or more band pass filters to respectively separate the positive mark, space and negative mark signals that may thereafter be added. Filtering and polarization beam splitting may also be used in the demodulator for improving the signal-to-noise ratio and preventing other types of degradation.
Inventors
- 👤 Hideaki Tsushima
- 👤 Shinya Sasaki
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 10:33
CPC Classifications
H; H04; H04L; H04L25/00; H04L25/38; H04L25/40; H04L25/49; H04L25/4917; H04L25/4923; H04L25/4925; H04B; H04B10/00; H04B10/60; H04B10/61; H04B10/614; H04L27/00; H04L27/10
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
119 words
An optical-electrical communication transmitter device, comprising: alternate mark inversion means (2) for converting a unipolar electrical signal (1) into a bipolar electrical signal (3), and having a bipolar electrical signal output and a unipolar electrical signal input for receiving information to be transmitted; semiconductor transducer means (7) for converting the bipolar electrical signal into an optical frequency shift keyed signal (8), and having an electrical input and an optical output; and electrical circuit means (5) operatively connecting said electrical output of said alternate mark inversion means (2) with said electrical input of said semiconductor transducer means (7) for forming a communication transmitter device converting between a unipolar electrical information input signal and a frequency shift keyed optical transmission signal.
Claim 2
Dependent Claim
119 words
An optical-electrical communication transmitter device, comprising: alternate mark inversion means (2) for converting a unipolar electrical signal (1) into a bipolar electrical signal (3), and having a bipolar electrical signal output and a unipolar electrical signal input for receiving information to be transmitted; semiconductor transducer means (7) for converting the bipolar electrical signal into an optical frequency shift keyed signal (8), and having an electrical input and an optical output; and electrical circuit means (5) operatively connecting said electrical output of said alternate mark inversion means (2) with said electrical input of said semiconductor transducer means (7) for forming a communication transmitter device converting between a unipolar electrical information input signal and a frequency shift keyed optical transmission signal.
Claim 3
Dependent Claim
52 words
The communication device according to claim 1, wherein said semiconductor transducer means (7) is a diode laser; said electrical circuit (5) including means combining a bias current (4) substantially higher than the threshold current of said diode laser with the bipolar electrical signal (3) output of said alternate mark inversion means (2).
Claim 4
Dependent Claim
64 words
The communication device according to claim 1, wherein said alternate mark inversion means (2) receives the unipolar electrical signal (1) having binary coded information as spaces and unidirectional marks serially contained in the signal at the input signal bit rate and alternates the mark signals as + and - signals about the space signals as a reference for producing the bipolar electric output signal.
Claim 5
Dependent Claim
64 words
An opto-electrical communication receiver device, comprising: means for receiving a frequency shift keying optical input information signal (8); and means (14, 16) for superhetrodyne converting the optical input information signal into an electrical output unipolar information signal, and including an optical to electrical transducer means (18) and demodulation means (28) for converting an alternate mark inversion electrical signal into a unipolar electrical information signal.
Claim 6
Dependent Claim
64 words
An opto-electrical communication receiver device, comprising: means for receiving a frequency shift keying optical input information signal (8); and means (14, 16) for superhetrodyne converting the optical input information signal into an electrical output unipolar information signal, and including an optical to electrical transducer means (18) and demodulation means (28) for converting an alternate mark inversion electrical signal into a unipolar electrical information signal.
Claim 7
Dependent Claim
99 words
The optical-electrical communication device according to claim 4, wherein said means for superhetrodyne converting includes a local power oscillator (14) producing a local oscillation light; an optical coupler (16) for optically combining the input frequency shift keying optical input information signal (8) with the local oscillation light (15) and producing a combined output light signal (17); said optical to electrical transducer means (18) converting said combined light signal into a frequency shift keying electrical signal (19); and amplifier means (20) for amplifying said frequency shift keying electrical signal (19) and feeding the amplified signal to said demodulation means (28A).
Claim 8
Dependent Claim
84 words
The communication device according to claim 4, wherein said optical to electrical transducer means (18) converts frequency shift keying optical signals (8) into a frequency shift keying electrical signal (18); demodulation means (28A) includes means for separating the frequency shifting keying electrical signal into first and second signal components; means (22) for delaying one of said components by a fixed amount to produce a delayed signal; means (23) for mixing said delayed signal and the other of said components to produce a mixed signal.
Claim 9
Dependent Claim
67 words
The communication device according to claim 6, including means (24) for filtering the positive mark signal, negative mark signal and space signal from the mixed frequency shift keying electrical signal from said mixing means (23) for eliminating other frequencies and producing a multi-polar baseband signal (25); and means (26) for alternate mark inversion decoding the multipolar baseband signal (25) to output the unipolar electrical information signal (27).
Claim 10
Dependent Claim
19 words
The communication device according to claim 4, wherein said optical to electrical transducer means (18) a semi conductor diode.
Claim 11
Dependent Claim
50 words
The communication device according to claim 6, wherein said means (22) for delaying having a delay time substantially equal to n/2fs, wherein n is a natural positive number, including zero, and fs is the frequency corresponding to the frequency of the space signal of the frequency shift keying electrical signal.
Claim 12
Dependent Claim
44 words
The communication device according to claim 4, wherein said demodulation means (28A) converts a frequency shift keying electrical signal by frequency discrimination into a baseband electrical signal and converts the baseband electrical signal by alternate mark inversion decoding into the unipolar electrical information signal.
Claim 13
Dependent Claim
111 words
The communication device according to claim 4, wherein said optical to electrical transducer means (18) outputs a frequency shift keying electrical signal (19); three separate band-pass filters (29A,B,C) respectively having band-pass frequencies corresponding to the positive mark frequency, negative mark frequency and space frequency of the frequency shift keying electrical signal for respectively outputting a positive mark signal (30A), a negative mark signal (30C) and a space signal (30B); and three envelope detector means (31A,B,C) for respectively converting the positive mark signal, negative mark signal and space signal to base band signals (32A,B,C), and means (33) for arithmetically combining said base band signals and outputting the unipolar electrical information signal (27).
Claim 14
Dependent Claim
68 words
The communication device according to claim 4, wherein said means for converting further a local oscillation power source includes automatic frequency control means for processing a sample of the frequency shift keying electrical signal from said optical to electrical transducer means to produce a processed signal differentially amplified to produce an output, and for controlling the frequency of the local oscillation power source according to the differential output.
Claim 15
Dependent Claim
90 words
A communication system including a transmitter (38) according to claim 1, and a receiver (40), comprising: means for receiving a frequency shift keying optical input information signal (8) and superhetrodyne converting the optical input information signal into a unipolar electrical output information signal (27), and including an optical to electrical transducer means and demodulation means for converting an alternate mark inversion electrical signal into a unipolar electrical information signal; and an optical transmission line (39) operatively connecting the output of said transmitter (38) and the input of said receiver (40).
Claim 16
Dependent Claim
127 words
The communication receiver device according to claim 4, including an optical coupling means (16) for combining local oscillation light (15) with the frequency shift keying optical input information signal (8) and producing a combined light beam; means for splitting said combined beam into two substantially equal light beam portions (17I, 17Q); said transducer means including separate optical to electrical transducer means (18I, 18Q) for respectively converting the light beam portions into two frequency shift keyed electrical signal portions; means arithmetically combining said electrical signal portions to produce a single frequency shift keying combined electrical signal (19) so that the noise of the local oscillator is effectively subtracted; and circuit means for feeding the frequency shift keying combined electrical signal to said demodulation means (28) as an input.
Claim 17
Dependent Claim
164 words
A receiver communication device according to claim 4, further including: local oscillation power means producing a local oscillation light (15); means (16) optically coupling said local oscillation light (15) with the input frequency shift keying optical input information signal (8) to produce a combined optical signal (17); polarization beam splitting means (37) for splitting said combined optical signal (17) into two optical frequency shift keyed beams (17X, 17Y) having polarization crossing each other orthogonally; separate optical to electrical transducer means (18X, 18Y) for respectively converting said beams into respective frequency shift keying electrical signals (19X, 19Y); two of said demodulation means (28X, 28Y) for respectively demodulating said frequency shift keying electrical signals and respectively outputting two unipolar electrical signals (27X, 27Y); and means (33) arithmetically combining said two unipolar electrical signals and producing a combined unipolar output information signal (27) so that the deterioration of the signal-to-noise ratio of the unipolar demodulation signal due to polarization fluctuation of the optical signal can be suppressed.
Claim 18
Dependent Claim
29 words
The receiver communication device according to claim 4, wherein said demodulation means (28C) includes envelope detection means (31) for detecting the envelope of a frequency shift keying electrical signal.
Claim 19
Dependent Claim
58 words
An optical receiver communication device, comprising: hetrodyne detection means (18) for converting a frequency shift keying alternate mark inversion optical signal (8) into a baseband electrical frequency shifting alternate mark inversion signal by frequency discrimination; and means (28) for converting said baseband electrical signal into a unipolar electrical information signal (27) by an alternate mark inversion decoder (26).
Claim 20
Dependent Claim
58 words
An optical receiver communication device, comprising: hetrodyne detection means (18) for converting a frequency shift keying alternate mark inversion optical signal (8) into a baseband electrical frequency shifting alternate mark inversion signal by frequency discrimination; and means (28) for converting said baseband electrical signal into a unipolar electrical information signal (27) by an alternate mark inversion decoder (26).
Claim 21
Dependent Claim
130 words
An optical receiver communication device, comprising: hetrodyne detection means (18) for converting a frequency shift keying alternate mark inversion optical signal (8) into a baseband electrical frequency shifting alternate mark inversion signal by frequency discrimination; and means (21) for converting said baseband signal into a unipolar information signal (27) by splitting the baseband signal into two components, delaying one of said components relative to the other components by a delay time equal to n/2fs, wherein n is a positive natural number including zero and fs is the frequency corresponding to the space signal of the alternate mark inversion frequency shift keying electrical signal, and combining the delayed component and other component without delay arithmetically to directly produce a unipolar electrical information signal without necessitating a separate alternate mark inversion decoder.
Claim 22
Dependent Claim
130 words
An optical receiver communication device, comprising: hetrodyne detection means (18) for converting a frequency shift keying alternate mark inversion optical signal (8) into a baseband electrical frequency shifting alternate mark inversion signal by frequency discrimination; and means (21) for converting said baseband signal into a unipolar information signal (27) by splitting the baseband signal into two components, delaying one of said components relative to the other components by a delay time equal to n/2fs, wherein n is a positive natural number including zero and fs is the frequency corresponding to the space signal of the alternate mark inversion frequency shift keying electrical signal, and combining the delayed component and other component without delay arithmetically to directly produce a unipolar electrical information signal without necessitating a separate alternate mark inversion decoder.
Claim 23
Dependent Claim
82 words
The communication device according to claim 4, wherein said demodulation means (28C) separates the frequency shift keying optical signal including alternate mark inversion into a positive mark electrical signal (30A), negative mark electrical signal (30C) and a space mark electrical signal (30B), by filtering, converts respectively said positive mark electrical signal, negative mark electrical signal and space signal by envelope detection into respective baseband electrical signals (32A,B,C), and arithmetically combines said baseband electrical signals for outputting the unipolar electrical information signal (27).
Claim 24
Dependent Claim
102 words
The optical receiver communication device according to claim 4, wherein said means for superhetrodyne detection includes means for producing a local oscillation light beam (15) from a local power oscillation source and coupling the local oscillation light beam optically with the input frequency shift keying alternate mark inversion optical input signal (8) to produce a combined optical signal (17); means (37) for splitting the combined optical signal (17) into at least two optical signal components (17X, 17Y); said means (18X, 18Y) for superhetrodyne detection separately hetrodyne detecting the optical components to separately produce corresponding frequency shifting keying electrical signal components (19X, 19Y).
Claim 25
Dependent Claim
139 words
The optical receiver communication device according to claim 4, further including said means for superhetrodyne converting including a local oscillation power source (14) producing local oscillation light (15); and automatic frequency control means for sampling the frequency shift keying electrical signal and producing a sample signal, for extracting at least two of a positive mark signal, negative mark signal and a space signal from said sample signal by respective band-pass filtering (29), inputting one of the extracted signals into a low pass filter (34B) and inputting another of the extracted signals into a high pass signal (34A) for producing respective passed signals, detecting the envelopes of the passed signals and controlling the frequency of the local oscillation power source (14) of local oscillation light so that the amplitudes of the two envelopes are substantially in conformity with each other.
References Cited (Backward Citations)
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