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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 24, Issue 8, 14 April 1988

Volumes & issues:

Volume 24, Issue 8

14 April 1988

Multiple-grid frequency-selective surfaces as periodically loaded structures
IIR adaptive filtering via discrete Legendre functions
  • Author(s): H. Perez  and  S. Tsujii
  • Source: Electronics Letters, Volume 24, Issue 8, p. 450 –451
  • DOI:  10.1049/el:19880304
  • Type: Article
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  • p. 450 –451 (2)
    A new IIR adaptive filter structure is proposed. It is based on modelling the impulse response of the system to be identified as a linear combination of a set of discrete orthogonal functions. Computer simulations show that the proposed structure has better convergence performance than FIR transversal filters, when they are required to identify systems with long impulse response. The comparison is made on the basis that both of them have the same number of multipliers.
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Electrical characterisation of Si-doped GaAs0.5Sb0.5 on InP grown by molecular beam epitaxy
High-speed 1.5μm self-aligned constricted mesa lasers grown entirely by MOCVD
  • Author(s): Y. Hirayama ; H. Furuyama ; M. Morinaga ; N. Suzuki ; M. Kushibe ; K. Eguchi ; M. Nakamura
  • Source: Electronics Letters, Volume 24, Issue 8, p. 452 –454
  • DOI:  10.1049/el:19880306
  • Type: Article
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  • p. 452 –454 (3)
    A self-aligning (SA) process technique to fabricate constricted mesa (CM) lasers is proposed. The controllability of GalnAsP active region volume and InP lateral confining layer widths were greatly improved. Lasers grown entirely by metalorganic chemical vapour deposition (MOCVD) showed very small variation in threshold currents (Ith = 15.2 = 1.1 mA) and in stray junction capacitances (C = 1.62 ± 0.08pF). A record bandwidth of 10GHz in the 1.5μm-wavelength region was demonstrated.
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Capacity of a neural network
High-speed front-illuminated GaInAsP/InP pin photodiode
  • Author(s): M.B. Yi ; J. Paslaski ; Y.-Y. Liu ; T.R. Chen ; A. Yariv
  • Source: Electronics Letters, Volume 24, Issue 8, p. 455 –456
  • DOI:  10.1049/el:19880308
  • Type: Article
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  • p. 455 –456 (2)
    We have developed a high-speed front-illuminated GaInAsP/InP pin photodiode for use at the optical wavelength of 1.3 μm. The device is grown on an n+-InP substrate and uses polyimide both as a passivation layer and as a bonding pad holder to reduce parasitic capacitance. An optoelectronic sampling measurement of the impulse response shows a pulsewidth (FWHM) of 28 ps. A 3dB bandwidth in excess of 18 GHz has been achieved.
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Fused coupler switch using a thermo-optic cladding
Electrorefraction in GaInAs/InP multiple quantum well heterostructures
  • Author(s): J.E. Zucker ; I. Bar-Joseph ; G. Sucha ; U. Koren ; B.I. Miller ; D.S. Chemla
  • Source: Electronics Letters, Volume 24, Issue 8, p. 458 –460
  • DOI:  10.1049/el:19880310
  • Type: Article
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  • p. 458 –460 (3)
    We report the first absolute measurement of electric-fieldinduced changes in refractive index in GalnAs quantum well heterostructures. Even for wavelengths as far as 40meV below the absorption edge, excitonic effects dominate electro-optic phase modulation. This effect close to resonance yields index changes two orders of magnitude larger than in bulk material. We find that the size of the index change, its dependence on applied voltage, and its behaviour with wavelength are well described in terms of the quantum confined Stark effect on excitonic absorption.
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High-Tc superconducting short dipole antenna
  • Author(s): S.K. Khamas ; M.J. Mehler ; T.S.M. Maclean ; C.E. Gough ; N.McN. Alford ; M.A. Harmer
  • Source: Electronics Letters, Volume 24, Issue 8, p. 460 –461
  • DOI:  10.1049/el:19880311
  • Type: Article
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  • p. 460 –461 (2)
    A recently discovered rare-earth copper-oxide material, which is superconducting above the temperature of liquid nitrogen, is used to fabricate a high-efficiency electrically short dipole antenna. Thus the necessity to cool a lead antenna structure to liquid helium temperatures is avoided. Results are presented which show the gain enhancement achieved using this new material when compared with a conventional copper structure at room temperature.
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Valley operator for extracting sketch features: DIP
Crosspolarisation characteristics of rectangular patch antennas
Heavy metal gettering in buried nitride silicon-on-insulator structures
  • Author(s): W. Skorupa ; P. Knothe ; R. Groetzschel
  • Source: Electronics Letters, Volume 24, Issue 8, p. 464 –465
  • DOI:  10.1049/el:19880314
  • Type: Article
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  • p. 464 –465 (2)
    Using Rutherford backscattering spectrometry the redistribution and gettering of implanted gold was investigated in silicon-on-insulator structures produced by high-dose nitrogen implantation. The gettering efficiency of a structure annealed at 1000°C containing a highly damaged silicon region near to the buried compound layer is more pronounced than that of a 1200°C-annealed structure with a lightly damaged silicon top layer. Gettering takes place at the interregion between silicon and silicon nitride.
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Adaptive controller yielding fast convergence rate
High-speed operation of 1.5μm GaInAsP/InP optoelectronic integrated laser drivers
New representation of FDMA traffic and associated on-board routers
Performance analysis of ICMA/CD multiple-access for a packet mobile radio
Algorithmic analogue/digital convertor based on current mirrors
Fibre-optic interferometric sensor utilising low coherence length source: resolution enhancement
  • Author(s): A.S. Gerges ; F. Farahi ; T.P. Newson ; J.D.C. Jones ; D.A. Jackson
  • Source: Electronics Letters, Volume 24, Issue 8, p. 472 –474
  • DOI:  10.1049/el:19880320
  • Type: Article
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  • p. 472 –474 (3)
    A fibre-optic interferometric sensor is described based on a low-coherence source. A novel form of homodyne signal processing is used in which the interferometer is locked to the quadrature point nearest to maximum visibility. This technique avoids the ambiguities which arise from the use of a high-coherence source in interferometers, where the transfer function is periodic.
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New error recovery strategy for 64 kbit/s video codecs
Crosstalk in a two-channel coherent fibre-optic ASK system using an optical amplifier and non-negligible linewidth lasers
  • Author(s): Y.K. Park ; S.W. Granlund ; L.D. Tzeng ; N.A. Olsson ; N.K. Dutta
  • Source: Electronics Letters, Volume 24, Issue 8, p. 475 –477
  • DOI:  10.1049/el:19880322
  • Type: Article
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  • p. 475 –477 (3)
    We present measurements of crosstalk penalties in a two-channel ASK system using 1.55μm DFB lasers and a semiconductor laser amplifier. The amplifier was operated well below gain saturation. No additional receiver sensitivity penalty due to the amplifier was observed for single channel operation. However, the additional crosstalk in the amplifier required a 10% increase of the channel spacing compared to the spacing in the nonamplifier system.
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Photorefractive two-wave mixing in GaAs using a diode-pumped Nd:YLF laser at 1.31 μm
All-single-mode-fibre interferometric polarisation beam splitter
Low-noise 0.78μm-band laser diode unit containing Faraday rotator
Automatic unit delay execution circuit for digital signal processing systems based on general-purpose microprocessors
Phase and logarithm of amplitude of a signal plus noise
LMS-based DHT analyser
  • Author(s): J.-C. Liu  and  T.-P. Lin
  • Source: Electronics Letters, Volume 24, Issue 8, p. 483 –485
  • DOI:  10.1049/el:19880328
  • Type: Article
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  • p. 483 –485 (3)
    A least-mean-square (LMS) adaptive algorithm for calculating the discrete Hartley transform (DHT) is presented. The transform kernel of the DHT serves as the input vector and the input signal to be analysed is regarded as the ‘desired response’ for the adaptive process. For a proper choice of convergent factor, i.e. u = 1/2, the ‘LMS DHT analyser’ will provide an exact N-sample DHT. All the operations involved are real. Incorporation of one new sample requires only one adaptation.
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Bit-serial realisations of maximum and minimum filters
Fibre transmission properties of optical pulses produced through direct phase modulation of DFB laser diode
  • Author(s): M. Shirasaki ; H. Nishimoto ; T. Okiyama ; T. Touge
  • Source: Electronics Letters, Volume 24, Issue 8, p. 486 –488
  • DOI:  10.1049/el:19880330
  • Type: Article
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  • p. 486 –488 (3)
    A scheme for gigabit range modulation without wavelength chirping is proposed. This technique uses the direct phase modulation property of a laser diode, and an optical interferometer with a time delay path. In a 4Gb/s experiment using a distributed feedback (DFB) laser diode with 1.54μm wavelength, the pulses passed through a 102 km nondispersionshifted fibre without being broadened.
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Low-pressure photochemical vapour deposition of silicon dioxidel on InP substrates
Progressive half-toning of images
Hard horns improve cluster feeds of satellite antennas
Hierarchy of terms in a multipole expansion
  • Author(s): J. van Bladel
  • Source: Electronics Letters, Volume 24, Issue 8, p. 492 –493
  • DOI:  10.1049/el:19880334
  • Type: Article
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  • p. 492 –493 (2)
    In the classical multipole expansion the various terms (dipoles, quadrupoles etc.) are ranked according to powers of the wavenumber k. When k→0 the dominant terms are those of lowest powers, provided the moments are k-independent. However, this situation does not always hold, and the hierarchy may be upset when the current structure markedly changes with k. The point is illustrated by the example of the confined modes of a dielectric resonator.
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High-fidelity music coding at 4 bits
  • Author(s): S.M.F. Smyth  and  J.V. McCanny
  • Source: Electronics Letters, Volume 24, Issue 8, p. 493 –495
  • DOI:  10.1049/el:19880335
  • Type: Article
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  • p. 493 –495 (3)
    A very high-quality sub-band ADPCM music coding scheme which compresses high-fidelity music signals, bandlimited to 15 kHz, to an equivalent PCM representation of only 4 bits per sample, is described. By processing music sampled at 32 kHz, this coder exhibits a total bit rate of only 128kbit/s and is consequently applicable to the ISDN. Subjective tests conducted with this coder have shown that music recovered from the compression scheme is essentially indistinguishable from the original material. The results obtained are of major importance, not only for ISDN and broadcasting, but also for other digital audio technology such as compact disc (CD) and digital audio tape.
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Gigabit/s performance of quarter-wavelength shifted DFB laser
Switched-capacitor neural networks for linear programming
High-current pulse-doped GaInAs MESFET
Study on the recurrences of pseudorandom array
Modal field transforming quartz single-mode fibre
Multirate switched capacitor system approach to frequency division multiplexing
Tunable DBR laser with wide tuning range
Erratum: Phase-locked induction heating inverter employing power MOSFETs

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