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image of Volume 21, Issue 25-26
Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 21, Issue 25-26, 5 December 1985

Volumes & issues:

Volume 21, Issue 25

5 December 1985

Economic comparison between TDM and SDM in small telephone systems
Fundamental limit to the performance of fibre-optic metallic glass DC magnetometers
Fabrication and characterisation of fluoride-glass single-mode fibres
Progressive picture transmission using interleaved blocks
  • Author(s): J. Cazin ; D.E. Pearson ; M. Whybray
  • Source: Electronics Letters, Volume 21, Issue 25, p. 1181 –1182
  • DOI:  10.1049/el:19850834
  • Type: Article
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  • p. 1181 –1182 (2)
    A method of progressive picture transmission is described which uses dynamically varying interleaved blocks. The method is easy to implement and has the effect of reducing the masking effect of the block structure during the early stages of transmission. The extent of the interleaving is reduced as more coefficients are received. Subjective tests are reported which indicate an appropriate strategy for dynamic variation.
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1.6 GHz electroabsorption light modulation in InGaAsP/InP double heterostructures with strip-loaded planar waveguide
  • Author(s): Y. Noda ; M. Suzuki ; Y. Kushiro ; S. Akiba
  • Source: Electronics Letters, Volume 21, Issue 25, p. 1182 –1183
  • DOI:  10.1049/el:19850835
  • Type: Article
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  • p. 1182 –1183 (2)
    Low-voltage driving and high-speed modulations of InGaAsP/InP electroabsorption modulators with strip-loaded planar waveguide have been described. The modulators were fabricated from VPE-grown InGaAsP/InP double-heterostructure wafers. For λ=1.55 μm incident light an extinction ratio of 20 dB was achieved with an applied voltage of ∼−6 V. The insertion loss was 9.6 dB. The calibrated 3 dB bandwidth was 1.6 GHz.
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Real-time demodulation of signals using statistical methods
Time-domain response of MIS coplanar waveguides for MMICs
  • Author(s): C. Seguinot ; M. El Kadiri ; P. Kennis ; P. Pribetich ; J.P. Villotte
  • Source: Electronics Letters, Volume 21, Issue 25, p. 1185 –1186
  • DOI:  10.1049/el:19850837
  • Type: Article
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  • p. 1185 –1186 (2)
    An MIS coplanar waveguide propagating a slow-wave mode has been characterised in the time domain. The theoretical analysis proposed to obtain the time-domain response of the line gives results in good agreement with measurements. The circuit analysis used is suitable for the determination of spurious propagation effects, inherent to the use of miniature waveguides encountered in MMICs, such as Schottky contact coplanar lines and coupled microstrip lines laid on MIS substrates.
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Dispersion-shifted convex-index single-mode fibres
Measurement of absorption coefficients of Ga0.47In0.53As over the wavelength range 1.0–1.7 μm
Capacity of wideband TDMA digital mobile radio cellular schemes
  • Author(s): P.A. Matthews
  • Source: Electronics Letters, Volume 21, Issue 25, p. 1189 –1191
  • DOI:  10.1049/el:19850840
  • Type: Article
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  • p. 1189 –1191 (3)
    Wideband TDMA digital cellular mobile radio schemes can offer a capacity similar to that of analogue modulation schemes. To find the optimum coding to be used a balance must be made between bandwidth, power and number of channels. A comparison is made for an idealised system using QPSK transmission and biorthogonal coding. Coding with a bandwidth expansion of 2.7 is shown to provide a good capacity at low carrier/noise ratio and an acceptable error rate.
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Calculation of maximum bulk electric field in high-voltage diodes with small and intermediate negative bevel angles
Current instabilities in Ga0.47In0.53As transferred-electron devices
  • Author(s): W. Kowalsky  and  A. Schlachetzki
  • Source: Electronics Letters, Volume 21, Issue 25, p. 1192 –1194
  • DOI:  10.1049/el:19850842
  • Type: Article
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  • p. 1192 –1194 (3)
    Time-resolved measurements of the device current in Ga0.47In0.53As transferred-electron devices are presented. The current drop, usually attributed to domain nucleation shows an unexpected behaviour because a drop of the device current of up to 90% is observed. This cannot be explained solely by the model of domain formation caused by electron transfer. The influence of transport properties of the central valley is discussed, giving rise to the assumption of its dominant effect on domain nucleation.
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Mode stability in real index-guided semiconductor laser arrays
Millimetre-wave response of InGaAsP lasers
Coupled coplanar waveguide with anisotropic substrate
  • Author(s): T. Kitazawa  and  Y. Hayashi
  • Source: Electronics Letters, Volume 21, Issue 25, p. 1197 –1198
  • DOI:  10.1049/el:19850845
  • Type: Article
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  • p. 1197 –1198 (2)
    Frequency-dependent hybrid-mode values of the characteristic impedances as well as the effective dielectric constants are presented for the coupled coplanar waveguide with uniaxially anisotropic substrate for the first time. The characteristic impedances are calculated by using two different definitions, that is, the voltage/current and power/voltage criteria, and both of them converge to the quasistatic values in lower-frequency ranges.
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Transmission experiments at 560 Mbit/s and 140 Mbit/s using single-mode fibre and 1300 nm LEDs
  • Author(s): J.L. Gimlett ; M. Stern ; R.S. Vodhanel ; N.K. Cheung ; G.K. Chang ; H.P. Leblanc ; P.W. Shumate ; A. Suzuki
  • Source: Electronics Letters, Volume 21, Issue 25, p. 1198 –1200
  • DOI:  10.1049/el:19850846
  • Type: Article
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  • p. 1198 –1200 (3)
    Transmission at 560 Mbit/s has been demonstrated using single-mode fibre and LEDs at 1300 nm. Surface-emitting, edge-emitting and super-radiant LEDs were used to transmit over maximum distances of 4.5 km, 15 km and 25 km, respectively. At 140 Mbit/s, the corresponding distances achieved with the same set of LEDs are 7.5, 35 and 50 km. respectively.
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Measurement of 1.3 and 1.55 μm gain-switched semiconductor laser pulses with a picosecond IR streak camera and a high-speed InGaAs PIN photodiode
  • Author(s): C. Lin  and  J.E. Bowers
  • Source: Electronics Letters, Volume 21, Issue 25, p. 1200 –1202
  • DOI:  10.1049/el:19850847
  • Type: Article
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  • p. 1200 –1202 (3)
    Gain-switched semiconductor laser pulses at 1.3 and 1.55 μm were measured both with a high-speed InGaAs PIN photodiode and an IR synchroscan streak camera. Gain-switching characteristics and their bias dependence observed with both detection schemes are consistent with each other. Laser pulses of 24–30 ps duration are observed. Picosecond pulses from a gain-switched 1.55 μm DFB laser are found to be chirped but not transform-limited.
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Phase-locked-loop analysis for pilot carrier coherent optical receivers
Coherent optical-fibre subscriber line
  • Author(s): E.-J. Bachus ; R.-P. Braun ; W. Eutin ; E. Groβmann ; H. Foisel ; K. Heimes ; B. Strebel
  • Source: Electronics Letters, Volume 21, Issue 25, p. 1203 –1205
  • DOI:  10.1049/el:19850849
  • Type: Article
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  • p. 1203 –1205 (3)
    A laboratory bidirectional four-channel broadband coherent-type fibre-optic subscriber line (3.5 km) is reported. The carriers are centre-frequency-stabilised by a ‘heterodyne spectroscope’ and demultiplexed by a tunable heterodyne receiver. In a very special state of the system, BER increases for nonlinear interaction between two counterpropagating narrowband lightwaves because of Brillouin scattering.
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Allpass filters using a current-controlled current source
Micromachining of three-dimensional silicon structures using photoelectrochemical etching
  • Author(s): L. Tenerz  and  B. Hök
  • Source: Electronics Letters, Volume 21, Issue 25, p. 1207 –1209
  • DOI:  10.1049/el:19850851
  • Type: Article
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  • p. 1207 –1209 (3)
    Photoelectrochemical etching of silicon in hydrofluonc acid solutions is proposed as a method for realising three-dimensional sensor and actuator elements. It is shown that high selectivity in etch rates between illuminated and dark areas can be obtained by a proper electrochemical bias. This can be implemented with an inert metal electrode, e.g. platinum. The technique could be useful for fabrication of beam and membrane structures for holographic gratings and for maskless small-volume production.
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1.3 μm InP/InGaAsP channelled-substrate buried-heterostructure laser monolithically integrated with a photodetector
Use of acoustic transducers as generalised electrical circuit elements
Measurement and prediction of digital radio performance on a long overwater path
  • Author(s): J. Steel ; J.C. Campbell ; L. Davey
  • Source: Electronics Letters, Volume 21, Issue 25, p. 1212 –1213
  • DOI:  10.1049/el:19850854
  • Type: Article
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  • p. 1212 –1213 (2)
    The simultaneous field trial performance of 34 Mbit/s 4PSK, 2 × 34 Mbit/s 8PSK and 4 × 34 Mbit/s 16QAM digital radio systems over a 158 km overwater path in Australia is reported, and the measured outage performance is then used to derive propagation data, which in turn is used to predict performance using quadruple diversity. In addition, a generalised outage prediction technique is derived for n diversity.
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Frequency multiplexing in an optical system using a Mach-Zehnder waveguide frequency translator
Envelope statistics of narrowband Cauchy noise
Results of a 12 GHz radiometric experiment in Hong Kong
  • Author(s): J.E. Allnutt  and  S.A.J. Upton
  • Source: Electronics Letters, Volume 21, Issue 25, p. 1217 –1218
  • DOI:  10.1049/el:19850857
  • Type: Article
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  • p. 1217 –1218 (2)
    At frequencies above 10 GHz, rain attenuation can be a significant factor in determining the operating margins of communications satellite systems, particularly for links to tropical, high-rainfall-rate regions. To establish accurate prediction models for those regions, it is necessary to conduct a number of measurements. The letter reports the results of one such experiment, utilising a 12 GHz radiometer, in Hong Kong.
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Sum of absolute grey level differences: an edge-preserving smoothing approach
Theoretical analysis of mode partition noise in single-frequency semiconductor lasers
  • Author(s): T.M. Shen  and  G.P. Agrawal
  • Source: Electronics Letters, Volume 21, Issue 25, p. 1220 –1221
  • DOI:  10.1049/el:19850859
  • Type: Article
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  • p. 1220 –1221 (2)
    The effects of mode partition noise in signal transmission using single-frequency lasers and dispersive fibres are analysed theoretically. Our analysis shows that the effect of fibre dispersion can easily be taken into account by considering the mode suppression ratio being reduced by a factor √2. Our results also show that under certain circumstances a mode suppression ratio as low as 400 is tolerable (with a power penalty <0.1 dB), and mode partition noise in single-frequency lasers is probably not a major noise source for lightwave communications compared with other effects such as wavelength chirp.
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Exact expression for stored energies in the cavity volume of microstrip antennas
110 km cost-effective transmission experiment at 140 Mbit/s using a 1.55 μm external-cavity BH laser
Improved noninvasive ‘fibredyne’ highway based on polarimetric detection of strain in polarisation-maintaining fibres
  • Author(s): J.P. Dakin  and  D.J. Pratt
  • Source: Electronics Letters, Volume 21, Issue 25, p. 1224 –1225
  • DOI:  10.1049/el:19850862
  • Type: Article
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  • p. 1224 –1225 (2)
    The letter reports a novel configuration of a noninvasive fibredyne highway, which has greatly improved optical efficiency, no need for a separate reference fibre and freedom from polarisation fading. Using a compensated polarimetric configuration, it can be used with semiconductor laser sources of relatively short coherence length. A received carrier/noise ratio of 55 dB has been achieved at 10 MHz with a 30 kHz bandwidth.
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Optical spectra and the system performance of 1.55 μm DFB lasers
  • Author(s): C.-Y. Kuo  and  M. Dixon
  • Source: Electronics Letters, Volume 21, Issue 25, p. 1225 –1227
  • DOI:  10.1049/el:19850863
  • Type: Article
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  • p. 1225 –1227 (3)
    Static and dynamic optical spectra of 1.55 μm DCPBH-DFB lasers are analysed. These lasers were packaged in hermetic sealed enclosures and directly modulated with transmitter circuitry. We have found that their static spectra observed under CW operation have fine structure induced by optical feedback from the far end of the package fibre pigtail. The dynamic spectra taken under pulsed modulation differ significantly from the static spectra in two ways. The dynamic spectra are narrower than the structured static spectra when a fixed data pattern is applied to the lasers and broader when a random data pattern is used. This difference is attributed to the finite build-up time required to produce a sustained amplitude oscillation at the relaxation oscillation frequency, within the external optical cavity, after the lasers are turned on. The structured CW and the altered dynamic spectra are found not to degrade the transmission through 50 km of fibre at bit rates as high as 650 Mbit/s.
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CORDIC-based HiFi digital FM demodulator algorithm for compact VLSI implementation
  • Author(s): J. Van Ginderdeuren ; L. Van Paepegem ; J. Lecocq ; R. Govaerts ; F. Catthoor ; P. Vandebroek ; S. Slock ; T.A.C.M. Claasen ; H. De Man
  • Source: Electronics Letters, Volume 21, Issue 25, p. 1227 –1229
  • DOI:  10.1049/el:19850864
  • Type: Article
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  • p. 1227 –1229 (3)
    A robust HiFi digital FM demodulation algorithm is discussed. Simulations demonstrate a performance surpassing analogue top-class receivers: a signal/noise ratio better than 90 dB for a sufficiently large carrier/noise ratio and a distortion level below 0.1% at 1 kHz modulation. For compact VLSI implementation, efficient shift-and-add-based CORDIC and IIR filter algorithms are used.
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Temperature measurement technique using Pt diffusion into Au for ion-implanting wafers mounted on a spinning disc
  • Author(s): S. Nakashima ; S. Kanamori ; K. Izumi
  • Source: Electronics Letters, Volume 21, Issue 25, p. 1229 –1230
  • DOI:  10.1049/el:19850865
  • Type: Article
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  • p. 1229 –1230 (2)
    A new technique using Au-on-Pt films to measure spinning wafer temperature during ion implantation has been developed. The technique utilises the phenomenon of Pt diffusion into Au in an Au/Pt system at high temperatures. Wafer temperature is calculated from the resistivity change of the Au film due to Pt diffusion. This technique was successfully applied to measure the temperature of wafers mounted on a spinning disc in oxygen-ion implantation.
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