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image of Volume 24, Issue 22
Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 24, Issue 22, 27 October 1988

Volumes & issues:

Volume 24, Issue 22

27 October 1988

Rugged all-fibre endless polarisation controller
  • Author(s): G.R. Walker  and  N.G. Walker
  • Source: Electronics Letters, Volume 24, Issue 22, p. 1353 –1354
  • DOI:  10.1049/el:19880925
  • Type: Article
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  • p. 1353 –1354 (2)
    A polarisation controller comprising four lengths of PM fibre wound onto piezoelectric cylinders has been produced. It is mechanically rugged, has an insertion loss of 1.5 dB, and is capable of endless control between two arbitrary time-varying states of polarisation. Polarisation control has been successfully demonstrated for the first time in a coherent optical transmission system over installed fibre.
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Field demonstration of 565 Mbit/s DPSK coherent transmission system over 176 km of installed fibre
New noninteractive identity-based key distribution system
  • Author(s): S. Tsujii ; K. Kurosawa ; T. Itoh
  • Source: Electronics Letters, Volume 24, Issue 22, p. 1356 –1357
  • DOI:  10.1049/el:19880927
  • Type: Article
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  • p. 1356 –1357 (2)
    The paper presents a new identity-based key distribution system (IDKDS), in which the common keys can be shared without auxiliary communications. The proposed IDKDS can be regarded as an identity-based version of Diffie and Hellman's key distribution system, and is a generalisation of the identity-based cryptosystem (IDC) developed by the authors. The paper also analyses the security of the IDKDS and shows that the IDKDS is practically secure.
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Integrated-optical circuit for fibre gyroscope applications
New pseudorandom/natural code conversion method
12 GHz FM bandwidth for a 1530 nm DFB laser
Design of highly selective two-dimensional recursive fan filters by relaxing symmetry constraints
Efficient operation of array-pumped Er3+ doped silica fibre laser at 1.5 μm
Noise figure for erbium-doped optical fibre amplifiers
Single-mode 1 × 3 integrated optical branching circuit design using phase-front accelerators
Generation of 1180 å period gratings with a Xe ion laser
Hardware fading simulator for a number of narrowband channels with controllable mutual correlation
New evaluation method for ARQ schemes
Multichannel FM video transmission using travelling-wave laser amplifier in 1300 nm subcarrier multiplexed optical system
Calculation of multicarrier intermodulation distortion in semiconductor optical amplifiers
  • Author(s): R.M. Jopson  and  T.E. Darcie
  • Source: Electronics Letters, Volume 24, Issue 22, p. 1372 –1374
  • DOI:  10.1049/el:19880939
  • Type: Article
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  • p. 1372 –1374 (3)
    We calculate the level of intermodulation distortion (IMD) produced by an arbitrary number of constant-amplitude carriers passing through an optical amplifier and also present an analytic upper bound on this distortion. For a total output intensity that is 0.1 times the amplifier saturation intensity, the composite IMD can be severe (7–20 dBc) unless a large channel separation (>1 GHz) is maintained.
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Integrated optics 90° hybrid on LiNbO3 for phase diversity receivers
Parameter re-estimation in semicontinuous hidden Markov modelling of speech with feedback to vector quantisation codebook
New structure of one-sided switching network
Heterojunction bipolar transistor utilising AlGaSb/GaSb alloy system
Image segmentation and approximation through surface type labelling and region merging
Robust frame synchronisation using standard VLSI synchronous input/output devices
  • Author(s): P.F. Driessen
  • Source: Electronics Letters, Volume 24, Issue 22, p. 1381 –1383
  • DOI:  10.1049/el:19880945
  • Type: Article
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  • p. 1381 –1383 (3)
    A robust frame synchronisation technique is proposed for serial data links which are to be implemented using standard VLSI synchronous input/output (SIO) hardward devices with a built-in 8-bit frame sync collector. This new technique uses a multiple byte marker and additional software for frame sync, and yields up to 4.6 dB improvement on noisy channels where forward error correction is used and only the SIO hardware is available.
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Electron velocity enhancement by planar-doped barrier source in GaAs vertical FET
Fourier-Bessel error performance analysis of 1024-QAM in error burst generating environments
  • Author(s): S.A. Kosmopoulos  and  M.D. Gouta
  • Source: Electronics Letters, Volume 24, Issue 22, p. 1384 –1386
  • DOI:  10.1049/el:19880947
  • Type: Article
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  • p. 1384 –1386 (3)
    A closed form performance evaluation of 1024-QAM in error burst generating channels is demonstrated in the letter. The noise model employed (which closely models atmospheric and ignition noise) consists of the additive mixture noise and a stream of Poisson impulses with amplitude areas distributed according to a bilateral Rayleigh PDF. Our results show that nonGaussian impulsive noise degrades the system performance significantly in comparison with the system performance in cochannel interference and demonstrate that the used Fourier-Bessel series approach is a powerful and very accurate computational tool.
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Si/SiGe heterostructure mitatt diode
Aging characteristics of AlGaAs/GaAs DFB lasers with a window structure
Self-checking time-division switch
Dopant distribution profile to improve performance of superlattice tunnel diode
Speaker adaptive vector quantisation of LPC parameters of speech
  • Author(s): K.Y. Lee ; A.M. Kondoz ; B.G. Evans
  • Source: Electronics Letters, Volume 24, Issue 22, p. 1392 –1393
  • DOI:  10.1049/el:19880952
  • Type: Article
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  • p. 1392 –1393 (2)
    Recently, it has been shown that good quality speech at rates as low as 6 Kbit/s can be achieved with CELP and its derivatives. However, in bringing down the bit rate even further these coding schemes have resorted to allocating fewer bits to the quantisation of the LPC parameters. It is known that CELP and its derivatives are sensitive to LPC parameters quantisation errors, and recently various schemes have been proposed to overcome this degradation. In the paper we describe how speaker adaptive vector quantisation (SAVQ) can be applied to the quantisation of LPC parameters and assess its performance when incorporated into a low bit rate coding scheme.
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Simple measurement of laser diode spectral linewidth using modulation sidebands
Reactive ion etched InP/GaInAs multiple quantum well rib waveguides grown by solid source MBE
Laser-direct-written capacitors and inductors for GaAs monolithic microwave integrated circuit trimming
  • Author(s): C.L. Chen ; J.G. Black ; S.P. Doran ; L.J. Mahoney ; R.A. Murphy ; D.J. Ehrlich
  • Source: Electronics Letters, Volume 24, Issue 22, p. 1396 –1398
  • DOI:  10.1049/el:19880955
  • Type: Article
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  • p. 1396 –1398 (3)
    Laser-direct-write deposition of tungsten and laser ablation techniques have been successfully used to modify monolithic capacitors and inductors fabricated on GaAs substrates. The properties of the tungsten inductors and capacitors have been characterised at microwave frequencies and are in good agreement with theory. The new techniques permit postfabrication tuning with precision and versatility that are not achievable by any other method
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Low-distortion lock-in discriminator
Comment: InP/Ga0.47In0.53As superlattice avalanche photodiode
Reply: InP/Ga0.47In0.53As superlattice avalanche photodiode
Simple technique to estimate spot sizes from far fields of single-mode fibres
  • Author(s): V. Priye ; Y. Gogia ; B.P. Pal
  • Source: Electronics Letters, Volume 24, Issue 22, p. 1400 –1401
  • DOI:  10.1049/el:19880959
  • Type: Article
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  • p. 1400 –1401 (2)
    Accurate estimates of two characteristic spot sizes, Wrms and Wf, based on measurements of far-field angles θ−3 dB and θ−40 dB made on two single-mode fibres of widely differing refractive index profiles (RIPs) are reported. The results including their near-field profiles are compared with those deduced from the measured RIPs of the fibres, and are found to be in good agreement and well within the measurement accuracy.
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