Showing papers on "Frequency-division multiplexing published in 1986"
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TL;DR: In this article, three 44 Mbit/s digital signals are transmitted along a single-mode fiber bus by intensity-modulating two 1.3 μ-wavelength, multimode laser diodes with FSK subcarriers, at frequencics between 3.5 and 4.0 GHz.
Abstract: We present a demonstration of subcarrier multiplexing in a lightwave multiple-access network. Three 44 Mbit/s digital signals are transmitted along a single-mode fibre bus by intensity-modulating two 1.3 μ-wavelength, multimode laser diodes with FSK subcarriers, at frequencics between 3.5 and 4.0 GHz. Intermodulation distotion, generated when two or more subcarriers are transmitted by the same laser, does not degrade the tranmission quality.
64 citations
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TL;DR: The design of an optical frequency-divisionmultiplexing distribution system is described and investigation is made of periodic filters for frequency division multiplexers and FS-SW, and the optical source, as well as single-mode fiber polarization mode dispersion.
Abstract: Optical frequency-division-multiplexing distribution systems providing more than ten frequency multiplexed optical signals separated by on the order of gigahertz, distribute signals to plural receivers, where one of the signals is selected by a frequency selection switch (FS-SW). This paper describes the design of an optical frequency-divisionmultiplexing distribution system. Investigation is made of periodic filters for frequency division multiplexers and FS-SW, and the optical source, as well as single-mode fiber polarization mode dispersion. Preliminary transmission experiments using a bit rate of 450 Mbits/s, fiber length of 13 km, and frequency spacing of 11 GHz are also demonstrated at a 1.5 μm wavelength to show the design's suitability.
50 citations
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04 Apr 1986
TL;DR: In this paper, the authors proposed a frequency division multiplexing (FDMM) system for optical fiber communications, which consists of generating a reference optical beam, generating a plurality of closely spaced optical carriers having frequencies which are coherently related to the reference frequency of the reference beam and which are capable of drifting with the reference beacon while maintaining coherence therewith, and combining the plurality of the closely spaced carriers to provide a multiplexed optical output beam.
Abstract: The method and associated system for providing increased information carrying capacity in optical fiber communication through frequency-division-multiplexing, comprising the steps of generating a reference optical beam, generating a plurality of closely spaced optical carriers having frequencies which are coherently related to the reference frequency of the reference optical beam and which are capable of drifting with the reference frequency while maintaining coherence therewith, and combining the plurality of closely spaced optical carriers to provide a multiplexed optical output beam. Advantageously, a frequency tracking optical beam tracks the reference optical beam and the plurality of closely spaced optical carriers of the multiplexed optical output beam are optically heterodyne detected by the tracking optical beam to convert the plurality of closely spaced optical carriers into a microwave spectrum, so that the individual carrier frequencies present in the microwave spectrum which correspond to the frequencies of the plurality of closely spaced optical carriers may be electronically heterodyne detected and separated from the microwave spectrum.
35 citations
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TL;DR: Three basic configurations, namely, parallel with a common reference, (ii) parallel with separate references and (iii) series, are studied for a multiplexed system of optical-fibre sensors, which ensures the separation of cross terms from desired signals.
Abstract: Three basic configurations, namely, (i) parallel with a common reference, (ii) parallel with separate references and (iii) series, are studied for a multiplexed system of optical-fibre sensors. With a frequency-modulated laser source, each sensor of a different predetermined path imbalance results in a different beat frequency at the detector and signals are multiplexed in the frequency domain. The cross-term problem arising from undesired interference associated with more than one sensor is described. A series configuration has more cross terms than a parallel configuration if there are four sensors or more and, consequently, suffers more signal power reduction if there are seven sensors or more. Several schemes are presented, which ensures the separation of cross terms from desired signals. In a parallel system with a common reference, signals and cross terms are allocated in the lower and in the higher region, respectively, or to every other line in the frequency domain. In a parallel system with separate references, sensors are made incoherent to each other to produce no cross terms. In a series system, more elaborate schemes are necessary. The estimated maximum number of sensors indicates that a parallel configuration should be used if there are 10 sensors or more to be multiplexed.
33 citations
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TL;DR: In this paper, an optical frequency-domain reflectometry technique is described as a method for multiplexing vibrating fiber-optic sensors, which is demonstrated with two vibrating elements resulting in an isolation of 38 dB.
Abstract: An optical frequency-domain reflectometry technique is described as a method for multiplexing vibrating fibre-optic sensors. The system has been demonstrated with two vibrating elements resulting in an isolation of 38 dB
23 citations
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TL;DR: An apparatus is described which performs optical processing on electrical signals to calculate the triple product integral in a manner which accommodates high bandwidth signals, which processes were formerly possible only in mechanically unstable designs.
Abstract: An apparatus is described which performs optical processing on electrical signals to calculate the triple product integral in a manner which accommodates high bandwidth signals, which processes were formerly possible only in mechanically unstable designs.
15 citations
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TL;DR: In this paper, an optical-frequency image-rejection mixer is proposed to provide 20 dB image rejection at an IF frequency of 1.7 GHz and is insensitive to fluctuations in the dimensions of the optical circuit.
Abstract: We demonstrate an optical-frequency image-rejection mixer, which provides 20 dB image rejection at an IF frequency of 1.7 GHz and is insensitive to fluctuations in the dimensions of the optical circuit. This mixer is especially useful in coher ent heterodyne optical networks using frequency-division multiplexing.
14 citations
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06 May 1986
TL;DR: In this article, a single fiber optical communication system (SFOCS) is proposed to provide full-duplex, bi-directional transmission with a single-person deployment and recovery of optical links.
Abstract: A single fiber optical communication system (SFOCS) allows, in many operational scenarios, one-person deployment and recovery of optical links. Wavelength division multiplexing (WDM) is employed to provide full-duplex, bi-directional transmission. An optical subsystem achieves the wavelength multiplexing and demultiplexing while at the same time allowing for an unpolarized terminal design. Selection by the system of the WDM operating wavelengths between a pair of SFOCS terminals is performed without operator intervention.
13 citations
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TL;DR: In this article, the operating principles and performance of waveguide Mach-Zehnder frequency translators suitable for use in coherent optical fiber systems are described, and the performance of a coherent optical fibre system transmitting analogue colour video signals and employing a Mach-ZEnder electro-optic waveguide device as a double sideband suppressed carrier frequency modulator is reported.
Abstract: The operating principles and performance of waveguide Mach-Zehnder frequency translators suitable for use in coherent optical fibre systems are described. The performance of a coherent optical fibre system transmitting analogue colour video signals and employing a Mach-Zehnder electro-optic waveguide device as a double sideband suppressed carrier frequency modulator is reported. It is shown that the receiver sensitivity of such a system may be as much as 21 dB greater than that for an equivalent direct detection system. The use of electro-optic frequency translators in coherent optical networks to assemble a frequency multiplex of wideband signals is described. Particular attention is given to the linearity of devices, in systems employing up to four channels, and it is shown that unwanted products can be suppressed to 30 dB below the signal level. The use of this type of device as a frequency control element in optical multichannel networks is also considered.
7 citations
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04 Dec 1986
TL;DR: In this article, the authors proposed an optical transmission equipment capable of suppressing the generation of clipping distortion by simple constitution and reducing the limitation of a transmission band by reducing the amount of optical modulation.
Abstract: PURPOSE: To provide an optical transmission equipment capable of suppressing the generation of clipping distortion by simple constitution and reducing the limitation of a transmission band CONSTITUTION: An AM signal line 110 multiplexes the frequency of plural AM signals and outputs the frequency-multiplex AM signal A soft clipper 130 constituted of an amplifier or the like non-linearly and moderately limits the large amplitude part (a part to be impulsively changed) of the frequency-multiplexed AM signal Then an attenuator 140 adjusts the level of the frequency-multiplexed AM signal so as to set up the signal to a prescribed degree of optical modulation On the other hand, a 16QAM signal source 120 multiplexes the frequency of plural 16QAM signals having respectively different carrier frequencies and outputs the frequency-multiplexed signal A frequency multiplexing part 150 multiplexes the frequency of the AM multiplex signal and the 16Q AM multiplex signal An optical transmitter 160 modulates the intensity of laser output light by a frequency multiplex signal outputted from the multiplexing part 150 and transmits the intensity-modulated signal At this time, no clipping distortion is generated An optical signal from the transmitter 160 is transmitted to a receiving system through an optical fiber 170 and demodulated
7 citations
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06 Mar 1986
TL;DR: In this paper, a line transmission system comprises n optical signal modulators (1-4) for modulating respective optical signals under the control of respective isochronous electrical signals (DI).
Abstract: A line transmission system comprises n optical signal modulators (1-4) for modulating respective optical signals under the control of respective isochronous electrical signals (DI). Multiplexing means (7-14) is provided for time division multiplexing the modulated optical signals to generate a multiplexed output signal so that multiplexing is carried out in the optical domain.
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04 Dec 1986TL;DR: In this paper, an amplitude uniform superposition of low-rate ISDN signals and high-rate signals in possibly overlapping frequency bands performed, where the Schmalbandund was superimposed on the wideband signal with a dependent bit rate ratio weighting each additive and the narrow band signal at the receiving end recovered by amplitude envelope curve demodulation and the wide band signal by amplitude limiting of the multi-stage in the amplitude sum signal.
Abstract: In a future broadband ISDN with preferably optical subscriber line the subscriber can access not only to the narrowband ISDN services but also to the broadband services (eg motion picture services). For transmission system integration of low-rate ISDN signals and high rate signals, the broadband electrical multiplexing can be made by a superposition of these signals in separate frequency transmission areas (frequency division multiplexed) or using an amplitude or phase modulation of the high rate signal. To prevent the required in frequency division multiplexing for good transmission quality high filtering and linearity requirement and to ensure an emergency operation without the high speed signal, which is difficult in a modulation method or the time division method, an amplitude uniform superposition of the two signals in possibly overlapping frequency bands performed. The transmitting end, the Schmalbandund be superimposed on the wideband signal with a dependent bit rate ratio weighting each additive and the narrow band signal at the receiving end recovered by amplitude envelope curve demodulation and the wideband signal by amplitude limiting of the multi-stage in the amplitude sum signal.
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20 May 1986TL;DR: It is shown that Orthogonal Frequency Division Multiplexing (OFDM), a parallel transmission method, can provide improved performance by spreading the effects of a fade over many bits.
Abstract: The Bit Error Rate (BER) performance of common data transmission schemes is quite poor when operating over the Rayleigh-fading mobile radio channel. This is due to the very high BER during fades. In (1) it is shown that Orthogonal Frequency Division Multiplexing (OFDM), a parallel transmission method, can provide improved performance by spreading the effects of a fade over many bits. This paper examines the performance of OFDM transmitted over an FM channel (OFDM/FM). Simulation results comparing OFDM/FM to Non-Coherent Frequency Shift Keying (NCFSK) indicate performance gains of 5 to 9 dB at a Bit Error Rate (BER) of 10-3but negligible improvements at a BER of 10-2.
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NEC1
TL;DR: An adaptive rate conversion filter is proposed to resolve a new problem in demodulating an individual channel signal from the TMUX output, caused by a difference between a TMUX operation rate and each SCPC symbol rate.
Abstract: In the near future, the on-board regenerative repeating system will be employed to convert many low speed SCPC signals to a high speed TDM signal. Similar situation can be considered in a star-network, where many small earth stations communicate with terrestrial telephone stations through a large size central earth station. In both cases, many SCPC signals are concentrated and demodulated by a central station. Therefore, hardware and power consumption minimization is necessary. This demand resulted in a group modulator/demodulator concept. A group demodulator employs the same hardware effectively in common in demodulating multiple PSK/FDM carriers. Actually, a transmultiplexer(TMUX) is used as a combination of a filterbank and down converters. Although a TMUX usually markedly reduces hardware, it introduces a new problem in demodulating an individual channel signal from the TMUX output. This problem is caused by a difference between a TMUX operation rate and each SCPC symbol rate. In this paper, an adaptive rate conversion filter is proposed to resolve this problem. In addition, each channel clock timing difference and carrier frequency offset are compensated for by channel demodulators attached individually to each TMUX channel output. The channel demodulator has been actually developed for 64kbps QPSK signal and its performance has been evaluated. Using this technique, a 16 channel group demodulator has been manufactured.
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03 May 1986
TL;DR: In this paper, a system for multi-channel transmission of digital and broadband video information in optical fiber communication for local area networks through frequency division multiplexing (FDMM) is described.
Abstract: A system is disclosed for providing multi-channel transmission of digital and broadband video information in optical fiber communication for local area networks through frequency-division-multiplexing. A plurality of closely spaced optical carrier wave pairs is generated with the optical carrier waves within each optical carrier wave pair having a predetermined separation frequency between one another. Each of the plurality of optical carrier wave pairs is assigned to a predetermined frequency slot and optically combining the plurality of optical carrier wave pairs to provide a multiplexed optical output wave. Advantageously, in addition to direct detection the plurality of optical carrier wave pairs may be detected by opto-electronic heterodyne detection and/or incoherent optical-heterodyne detection to electronically recover the optical carrier wave pairs.
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01 Jan 1986
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TL;DR: In this article, a new WDM (wavelength division multiplexing transmission configuration for local communications) was proposed, in which the demultiplexing function is performed using narrow spectral sensitivity optical detectors and a demuliplexer is not required, allowing economical and simple WDM transmission.
Abstract: A new WDM (wavelength division multiplexing transmission configuration for local communications is proposed. In this configuration, the demultiplexing function is performed using narrow spectral sensitivity optical detectors and a demultiplexer is not required, allowing economical and simple WDM transmission. Dual-wavelength WDM transmission of 0.86 ?m and 0.73 ?m over 2 km on GI fibre is experimentally confirmed, using commercially available LEDs for both optical sources and detectors.
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TL;DR: In this article, a tree-type interconnection of SOLARnets at layer 1 and enlarges the network scale using WDM is used to overcome self-collision (collision of the packet header with its packet).
Abstract: A repeater for the 32 Mbit/s star-configured optical local area network (SOLARnet) has been developed This repeater permits a tree-type interconnection of SOLARnets at layer 1 and enlarges the network scale Wavelength-division multiplexing (WDM) is used to overcome self-collision (collision of the packet header with its packet)
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01 Jan 1986
TL;DR: Each new release of this document will reflect the latest updated design specification for the FDM-TDM Digital Transmultiplexer.
Abstract: The information in this document has been carefully checked and is believed to be entirely reliable. However, no responsibility is assumed for inaccuracies. Furthermore, Applied Signal Technology, Inc. reserves the right to discontinue or make changes, without prior notice, to any products herein to improve reliability, function, or design. Applied Signal Technology, Inc. advises its customers to obtain the latest version of the relevant information to verify, before placing orders, that the information being relied upon is current. Each new release of this document will reflect the latest updated design specification for the FDM-TDM Digital Transmultiplexer. New release changes may be noted below. All trademarks are the property of their respective companies.
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14 Jun 1986
TL;DR: In this article, a means for varying bias resistance of a varactor diode to decrease an output power of a frequency multiplier and isolation of a high frequency switch thereby miniaturizing the high-frequency switch is provided.
Abstract: PURPOSE:To improve the reliability and reduce the cost by varying a bias resistance of a varactor so as to decrease an output power of a frequency multiplier and isolation of a high frequency switch thereby miniaturizing the high frequency switch. CONSTITUTION:A means varying a bias resistance of the varactor diode 16 is provided. For example, two bias resistors 38, 40 having different resistance and a switch 42 connecting the bias resistors 38, 40 and a coil 14 are provided. Thus, the frequency multiplication efficiency is changed and the isolation of the high frequency switch is decreased in a radio equipment, then the high frequency switch is formed inexpensively and the reliability is improved and miniaturization is attained.
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04 Sep 1986
TL;DR: In this paper, a method and apparatus are used to transmit by a televison signal cable system derived from a received television signal type MAC frequency modulation, where the digital part of the MAC-type television signal is received or transmitted is converted to a duo-binary form.
Abstract: A method and apparatus are used to transmit by a televison signal cable system derived from a received television signal type MAC frequency modulation. The digital part of the MAC-type television signal is received or transmitted is converted to a duo-binary form. The MAC type duobinary television signal is used to generate a remaining sideband television signal frequency modulated transmitted through the cable system, the frequency modulated television signal thus generated having a frequency deviation of less than that of the received MAC-type television signal. The transmitted signals are applied to a television receiver by the waves of a type adapted to receive MAC type signals to frequency modulation.
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07 Apr 1986
TL;DR: In this article, an amplitude limiting section and band limiting section on the video signal input side and the coupling section of video signals and out-band signals after the band limiting sections were provided to reduce bad influences to outband signals caused by the surge of video signal inputs.
Abstract: PURPOSE:To reduce bad influences to out-band signals caused by the surge of video signal inputs, by providing an amplitude limiting section and band limiting section on the video signal input side and the coupling section of video signals and out-band signals after the band limiting section CONSTITUTION:When frequency multiplexing is performed on a video signal of 4-MHz band and FSK signals having a center frequency of 6MHz and maximum frequency shift of 200kHz, an amplitude limiting section 1 and band limiting section 3 which stops frequency components of 6MHz+ or -200kHz are provided on the video signal input side and a coupling amplifier 2 is provided after the band limiting section 3 and frequency multiplexing coupling is made on the video signal and FSK signal Since the amplitude is limited by a surge limiter 1 when video signals are inputted and the higher harmonic produced then is stopped by the band limiter 3, multiplexed signals are coupled and outputted by the amplifier 2 without giving any disturbance to the FSK signals
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12 Jun 1986
TL;DR: In this article, the authors proposed a method to obtain a high quality voice signal or digital data by converting an audio signal to a PCM digital signal, and recording and regenerating by frequency multiplexing outside the occupied bandwidth of a low carrier FM luminance signal and low-level conversion chromaticity signal.
Abstract: PURPOSE:To obtain a high quality voice signal or digital data by converting an audio signal to a PCM digital signal, and recording and regenerating by frequency multiplexing outside the occupied bandwidth of a low carrier FM luminance signal and low-level conversion chromaticity signal, or the gap of the occupied bandwidth of the both signals. CONSTITUTION:The audio signal from a terminal 2 is once converted to a digital signal in an A/D converter 20, is added a synchronizing signal and error code in a digital processing circuit 21, is performed an interleave, and is recorded on a video truck by the frequency multiplexing to the outside the occupied bandwidth of the low-level conversion chromaticity signal and low carrier FM luminance signal from recording signal spectrum or the gap between the occupied bandwidth of the both signals made by a modulation signal 22 and mixer 14. In regenerating, a voice modulation signal is taken out from the signal regenerated by video heads 16a and 16b. The original digital signal is demodulated in a demodulation circuit 42 and digital processing circuit 43, and the original voice signal is demodulated in a D/A converter. This eliminates the influence of distortion of a recording media, permitting high quality voice transmission.
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20 Nov 1986
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06 Jul 1986
TL;DR: In this article, a 1.5 micron wavelength was used to confirm feasibility of a laser diode frequency stabilizing circuit and a narrow channel spaced optical demultiplexer.
Abstract: 450 Fbps 13 km optical frequency-division-multiplexing transmission with 11 GHz channel spacing was demonstrated at a 1.5 micron wavelength to confirm feasibility of a laser diode frequency stabilizing circuit and a narrow channel spaced optical demultiplexer. Frequency utilization efficiency was 0.08 bps/Hz.