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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 24, Issue 10, 12 May 1988

Volumes & issues:

Volume 24, Issue 10

12 May 1988

Novel optically excited resonant pressure sensor
Improved circuit implementation of adaptive phase comparators
  • Author(s): J.C. Haartsen  and  R.C. den Dulk
  • Source: Electronics Letters, Volume 24, Issue 10, p. 574 –576
  • DOI:  10.1049/el:19880390
  • Type: Article
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  • p. 574 –576 (3)
    An improved implementation of an adaptive phase comparator circuit is presented. The adaptive phase comparator can be thought of as a five-cell up-down counter that is bounded in both the outermost cells. A new design concept leads to a circuit with a higher maximum operation frequency while maintaining the basic requirements of handling coincident input signals and absence of intermediate states. The circuit is based on the application of a number of identical logic elements, which are placed in a ring structure.
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Field experiments of narrowband digital FM transmissions with diversity reception at 1.45 GHz carrier frequency
Tuning ranges for 1.5 μm wavelength tunable DBR lasers
Random code chaining
Crosstalk characteristics of a 100 km-long spliced polarisation maintaining optical fibre
  • Author(s): Y. Sasaki ; K. Tajima ; M. Tsubokawa ; K. Suzuki
  • Source: Electronics Letters, Volume 24, Issue 10, p. 580 –582
  • DOI:  10.1049/el:19880394
  • Type: Article
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  • p. 580 –582 (3)
    Crosstalk of −10.1 dB in a 100 km-long spliced polarisationmaintaining optical fibre has been achieved at 1.56 μm wavelength. The fibre has been constructed from 14,125 μm-diameter PANDA fibres, with an average modal birefringence of 4.8×10−4, by conventional arc-fusion splice techniques. An average transmission loss of 0.37 dB/km, including the splice loss, has been obtained at 1.56 μm wavelength.
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Polarisation fluctuations of optical fibre submarine cable in 6000 m deep sea trial
  • Author(s): Y. Namihira ; S. Ryu ; H. Wakabayashi
  • Source: Electronics Letters, Volume 24, Issue 10, p. 582 –583
  • DOI:  10.1049/el:19880395
  • Type: Article
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  • p. 582 –583 (2)
    The difference between the polarisation fluctuations of an optical fibre submarine cable during laying and recovery in a 6000 m deep sea trial is discussed. State of polarisation variations in real time (∼6msec) were measured by a Stokes parameter analyser using an LiNbO3 device. The maximum power spectra of the polarisation fluctuations during cable laying and recovery were less than 50Hz.
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Simplified fast least-squares algorithms for speech predictors
  • Author(s): C.C. Evci  and  M.G. Bellanger
  • Source: Electronics Letters, Volume 24, Issue 10, p. 583 –585
  • DOI:  10.1049/el:19880396
  • Type: Article
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  • p. 583 –585 (3)
    The letter deals with the development of a simplified fast least-squares algorithm which is free of roundoff error accumulation. The simplified algorithm requires 9N MADPR (multiplications and divisions per recursion) rather than 10N MADPR as in the fast least squares or fast Kalman (FLS) case where N is the order of predictor. The superiority of SFLS over FLS and LMS approaches is illustrated by prediction gain performance curves for various speech signals.
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Measurement of the statistics of DFB laser frequency fluctuations
Performance of PSK signal transmitted over satellite channel
GaAs/AlGaAs heterojunction Pnp bipolar transistors grown on (100) Si by molecular beam epitaxy
  • Author(s): T. Won ; C.W. Litton ; H. Morkoc ; A. Yariv
  • Source: Electronics Letters, Volume 24, Issue 10, p. 588 –590
  • DOI:  10.1049/el:19880399
  • Type: Article
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  • p. 588 –590 (3)
    GaAs/AlGaAs Pnp heterojunction bipolar transistors (HBTs) were fabricated and tested on (100) Si substrates for the first time. A common-emitter current gain of β = 8 was measured for the typical devices with an emitter area of 50×50 μm2 at a collector current density of 1×104 A/cm2 with no output negative differential resistance up to 280 mA, highest current used. A very high base-collector breakdown voltage of 10 V was obtained. Comparing the similar structures grown on GaAs substrates, the measured characteristics clearly demonstrate that device grade hole injection can be obtained in GaAs on Si epitaxial layers despite the presence of dislocations.
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Photochromic behaviour of thulium-doped silica optical fibres
New ARQ transmission scheme involving zero-crossing channel evaluation
Some new approaches to improved low-loss SAW bandpass filters
Rearrangeably nonblocking 8 × 8 guided wave optical switch
Miniature fibre optic polariser
Impulse-doped GaAs power FETs for high efficiency operation
Electronically tunable external-cavity semiconductor laser
Self-reconfiguring interconnection network for a fault-tolerant mesh-connected array of processors
  • Author(s): S. Pateras  and  J. Rajski
  • Source: Electronics Letters, Volume 24, Issue 10, p. 600 –602
  • DOI:  10.1049/el:19880407
  • Type: Article
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  • p. 600 –602 (3)
    An interconnection network capable of spontaneously reconfiguring a mesh-connected processor array on detection of faulty processors is presented. Although the reconfiguration process is global in nature, the network control circuitry is localised around each processor and is therefore completely modular. In addition, the structure of the control circuitry is fixed and thus independent of the array size or the number of spare processors.
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Efficient zero-phase constrained frequency-domain block LMS adaptive algorithm
Amplitude and phase modulation in a 4μm-thick GaAs/AlGaAs multiple quantum well modulator
Real time parallel tomographic ultrasound imaging using transputers
  • Author(s): B.S. Hoyle  and  F. Wiegand
  • Source: Electronics Letters, Volume 24, Issue 10, p. 605 –606
  • DOI:  10.1049/el:19880410
  • Type: Article
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  • p. 605 –606 (2)
    An evaluation is described of the application of a Transputer array in the real-time parallel implementation of the acoustic backprojection algorithm, which forms the basis for tomographic imaging using backscattered ultrasound. The low cost, real-time processing implementation described is thus potentially applicable to this form of imaging in a variety of fields: nondestructive testing, noninvasive medical diagnosis, and also in the imaging of industrial processes, such as complex fluid mixtures in pipes. An overview of the parallel processing method is given with sample results which indicate the viability of real-time processing.
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Integrated-optical single-sideband Bragg modulator with tapered waveguides
All-fibre, diode-pumped recirculating-ring delay line
Very low threshold operation of 1.52 μm GaInAsP/InP DFB buried ridge structure laser diodes entirely grown by MOCVD
  • Author(s): A. Talneau ; D. Rondi ; M. Krakowski ; R. Blondeau
  • Source: Electronics Letters, Volume 24, Issue 10, p. 609 –611
  • DOI:  10.1049/el:19880413
  • Type: Article
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  • p. 609 –611 (3)
    1.52 μm GaInAsP/InP DFB laser diodes with a buried ridge structure were fabricated entirely by MOCVD, with a second-order corrugation on the GaInAsP guiding layer. The 5 mA minimum threshold current achieved is believed to be the lowest yet reported for DFB lasers. Single longitudinalmode operation with a side-mode suppression ratio greater than 35 dB was obtained from 20°C (up to 16 mW) to 90°C (up to 3 mW).
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Simultaneous transmission of 2 Gbit/s digital data and ten FM-TV analogue signals over 16.5 km SM fibre
  • Author(s): W.I. Way  and  C. Castelli
  • Source: Electronics Letters, Volume 24, Issue 10, p. 611 –613
  • DOI:  10.1049/el:19880414
  • Type: Article
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  • p. 611 –613 (3)
    The simultaneous transmission of a 2 Gbit/s digital signal and ten channels of FM-TV signals (3.7–4.2 GHz) over a 16.5 km single-mode fibre is reported. The system uses a 1300 nm directly modulated multimode laser diode without optical isolators, a ternary pin diode, and a simple commercial 50Ω wideband amplifier as a front-end preamp. The combined transmission of digital and analogue signals via single-mode fibre is of potential value in transition scenarios to future BISDN systems.
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Dependence of spectral linewidth on cavity length and coupling coefficient in DFB laser
  • Author(s): S. Ogita ; Y. Kotaki ; K. Kihara ; M. Matsuda ; H. Ishikawa ; H. Imai
  • Source: Electronics Letters, Volume 24, Issue 10, p. 613 –614
  • DOI:  10.1049/el:19880415
  • Type: Article
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  • p. 613 –614 (2)
    The dependence of the spectral linewidth of DFB lasers on cavity length and coupling coefficient has been investigated. It was shown experimentally that the long cavity was very effective at reducing the spectral linewidth of DFB lasers, whereas a large coupling coefficient was ineffective. With a corrugation depth of 15 nm and a cavity length of 1200 μm, a narrow linewidth of 1.7 MHz was obtained at 11 mW.
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Eigenstate calculation of quantum well structures using finite elements
  • Author(s): K. Hayata ; M. Koshiba ; K. Nakamura ; A. Shimizu
  • Source: Electronics Letters, Volume 24, Issue 10, p. 614 –616
  • DOI:  10.1049/el:19880416
  • Type: Article
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  • p. 614 –616 (3)
    The finite-element technique based on a Galerkin method is applied to the eigenstate problem of semiconductor quantum wells with arbitrary potential profiles. In the present formulation, finite elements are employed only within the well region, and the contribution of the semi-infinite barrier region is evaluated analytically. Self-consistent solutions are obtainable by solving a matrix eigenvalue problem iteratively.
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Summing networks using neural optimisation concept
Using simulated annealing to design digital transmission codes for analogue sources
Neural net based nonstandard A/D conversion
New integral transform between analogue and discrete systems
Fibre ring resonator with finesse of 1260
Beam converging laser diode by taper ridge waveguide
Direct synthesis approach for GIC digital filters
  • Author(s): K. Manivannan  and  C. Eswaran
  • Source: Electronics Letters, Volume 24, Issue 10, p. 624 –626
  • DOI:  10.1049/el:19880423
  • Type: Article
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  • p. 624 –626 (3)
    For designing nth-order digital filters from an active reference configuration comprising generalised-immittance convertors and resistors, a method proposed in earlier work makes use of second-order filter sections as building blocks in a cascade synthesis. A direct approach for designing such filters is presented in this letter. The proposed method yields a new class of wave digital filters distinct from the already known structures which are based on the doubly-terminated LC networks.
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Phase-dominant spatial light modulators
Parallel processing in communication systems simulation
  • Author(s): B. Rashidzadeh  and  P.A. Matthews
  • Source: Electronics Letters, Volume 24, Issue 10, p. 627 –628
  • DOI:  10.1049/el:19880425
  • Type: Article
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  • p. 627 –628 (2)
    The development of a transputer-based work station for communications system simulation is discussed. The advantages which can be gained and the limitations which have been found in parallel processing using transputers are described. The speed of operation of the interactive work station is compared with the speed of previous versions of the simulation running as serial programs on VAX computers. The speed of the work station using five transputers is better than all except the most powerful mainframe computers and may be increased by the inclusion of more transputers in the system.
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Optically pumped GaAs surface-emitting laser with integrated Bragg reflector
Current mode analogue circuit for implementing artificial neural networks
Hemispherical coverage antenna for spacecraft
Model of error generation in tamed frequency modulation
  • Author(s): T.J. Moulsley ; D.J. Goodman ; P.R. Holmes
  • Source: Electronics Letters, Volume 24, Issue 10, p. 633 –634
  • DOI:  10.1049/el:19880429
  • Type: Article
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  • p. 633 –634 (2)
    In digital communication systems a knowledge of the transmission error statistics is necessary in the design of appropriate error control procedures, such as retransmission protocols or error-correcting codes. The probability of occurrence of different error patterns has been measured for a TFM (tamed frequency modulation) demodulator subject to additive white Gaussian noise. Good agreement is obtained with a theoretical model of the error generation process.
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Polarisation-maintaining optical fibres with Al2O3 stress-applying parts
1.2 Gbit/s, 201 km optical DPSK heterodyne transmission experiment using a compact, stable external fibre cavity DFB laser module
Low threshold current GaInAs/AlInAs ridge mow lasers with InP cladding layers
  • Author(s): Y. Kawamura ; K. Nonaka ; O. Mikami
  • Source: Electronics Letters, Volume 24, Issue 10, p. 637 –638
  • DOI:  10.1049/el:19880432
  • Type: Article
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  • p. 637 –638 (2)
    GaInAs/AlInAs ridge MQW lasers with InP cladding layers were fabricated by molecular beam epitaxy. The threshold current is as low as 60 mA and the lasing wavelength is 1.52μm under pulsed conditions. The use of InP cladding layers made it possible to realise narrow-stripe-width ridge MQW lasers with low threshold currents. The characteristic temperature To is 88 K, which was greater than those reported for GaInAsP double heterostructure lasers in the 1.5μm wavelength region.
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Nonlinear interactions in optical amplifiers for multifrequency lightwave systems
  • Author(s): T.E. Darcie  and  R.M. Jopson
  • Source: Electronics Letters, Volume 24, Issue 10, p. 638 –640
  • DOI:  10.1049/el:19880433
  • Type: Article
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  • p. 638 –640 (3)
    Nonlinear interactions that occur in an optical amplifier between the carrier density and multiple optical signals, are described using a small-signal analysis. In multifrequency lightwave systems with channel separations less than 1 GHz, the ratio of the signal power to the total intermodulation interference may be less than 25 dB, for total output intensities 10dB below the amplifier saturation intensity.
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Least-squares boundary residuals solution of microstrip step discontinuities
  • Author(s): F.A. Fernandez  and  J.B. Davies
  • Source: Electronics Letters, Volume 24, Issue 10, p. 640 –641
  • DOI:  10.1049/el:19880434
  • Type: Article
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  • p. 640 –641 (2)
    The symmetric step junction of two shielded micro-strip transmission lines is analysed with the combined use of the spectral domain-Galerkin method applied to each microstrip, and the least-squares boundary residual method to match electric and magnetic fields at the discontinuity. Preliminary results are shown for a simple structure. This method can be extended to finline and in general to multidielectric and multiconductor transmission lines.
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Polarisation phase-shift keying: a coherent transmission technique with differential heterodyne detection
Performance of mean-level detector in presence of multiple-tone interference plus noise
Sampling effects in square-law detected synthetic aperture radar
  • Author(s): D.J. Wingham
  • Source: Electronics Letters, Volume 24, Issue 10, p. 645 –646
  • DOI:  10.1049/el:19880437
  • Type: Article
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  • p. 645 –646 (2)
    An earlier letter demonstrated that a narrow synthetic radar beam may be generated from square-law detected radar pulses provided the return pulse is incoherent. This technique would have the significant advantage of reducing the required knowledge of the platform location to a fraction of the transmitted pulse length, rather than the fraction of the carrier wavelength required by a coherent synthetic aperture radar. The effect of sampling the aperture is now described, and it is shown that the sampling interval required to avoid unacceptable sidelobe levels can be very much greater than that required by coherent synthetic aperture radar.
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Mode-field radius of noncircular field single-mode fibre: new definition and application to calculation of splice loss and waveguide dispersion

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