# Electronics Letters

## Filter Results

Displaying Results 1 - 25 of 52
• ### Texture analysis approach for improving HMM speech recognition in presence of microinterruptions

Publication Year: 1999, Page(s):453 - 454
| | PDF (274 KB)

A simple yet powerful algorithm for enhancing a signal corrupted by microinterruptions is outlined. The algorithm performs a texture analysis of the peak-based spectrogram image for correcting the damage caused by noise and has been used as a pre-processor in hidden Markov model (HMM) speech recognition. Improvements in accuracy as high as 16% have been obtained with the T120 database. View full abstract»

• ### Designing optimal image feature detection masks: equal area rule

Publication Year: 1999, Page(s):463 - 465
Cited by:  Papers (1)
| | PDF (428 KB)

The problem of designing optimal templates for detecting image features is discussed. An equal area rule is derived which reduces the uncertainty involved when masks with a large number of free parameters have to be designed. View full abstract»

• ### Gray codes and the symbolic dynamics of quadratic maps

Publication Year: 1999, Page(s):468 - 469
| | PDF (281 KB)

Alvarez et al. [1998] used Gray codes to study the symbolic sequences with two symbols which arise from superstable orbits of iterations of quadratic maps. They state several results without proof. A simplified version of this idea is presented, and proofs for the assertions proposed are presented. View full abstract»

• ### Room temperature laser operation of bulk InGaAsN/GaAs structures grown by AP-MOVPE using N/sub 2/ as carrier gas

Publication Year: 1999, Page(s):474 - 475
Cited by:  Papers (1)
| | PDF (266 KB)

Long wavelength bulk InGaAsN semiconductor laser structures have been grown on GaAs substrate by AP-MOVPE, using DMHY and TBAs. After thermal annealing, GaAs/InGaAsN, and AlGaAs/InGaAsN Fabry-Perot laser diodes were processed from the wafers. At room temperature, stimulated emission was observed at peak wavelength from 1.15 to 1.38 /spl mu/m, and laser operation was achieved at 1.16 and 1.275 /spl... View full abstract»

• ### Process capability of local oxidation of silicon isolation technology for sub-half micrometre custom IC applications

Publication Year: 1999, Page(s):505 - 506
| | PDF (280 KB)

The process capability of conventional LOCOS isolation for sub-half micrometre custom IC applications is investigated in terms of field oxide thinning and bird's beak encroachment. A 0.4 /spl mu/m isolation space appears to be the practical limit when the appropriate film thickness combination is used. View full abstract»

• ### Active waveguides patterned in mixed 2D-3D metallic photonic crystal

Publication Year: 1999, Page(s):475 - 477
Cited by:  Papers (4)
| | PDF (348 KB)

Active metallic waveguides based on photonic bandgap structures are proposed. Their operation relies on the electromagnetic properties of mixed two- and three-dimensional photonic crystals. Tuning is induced by reflectivity modulation of the waveguide walls by means of varactor diodes View full abstract»

• ### Zero-delay channel estimation based on pilot and traffic channels for DS/CDMA systems

Publication Year: 1999, Page(s):457 - 459
| | PDF (308 KB)

A channel estimation scheme, based on both pilot and traffic channels, is proposed for next generation DS/CDMA systems. This scheme has no channel estimation delay, and is found to perform significantly better than a scheme based on only the pilot channel View full abstract»

• ### Coherent frequency/phase modulation scheme

Publication Year: 1999, Page(s):444 - 445
Cited by:  Papers (1)
| | PDF (208 KB)

An L-phase-levelled coherent frequency/phase modulation (LCFPM) scheme is proposed and analysed for additive white Gaussian noise channels. The optimised LCFPM scheme with L>2 is found to have superior bandwidth efficiency to the conventional dual-frequency quadrature frequency/phase modulation scheme View full abstract»

• ### Very low rate speech coding using temporal decomposition

Publication Year: 1999, Page(s):456 - 457
| | PDF (232 KB)

A method for encoding the spectral characteristics of speech, at rates below 180 bit/s, using hierarchical temporal decomposition (HTD) is proposed. A set of the log-area-ratio (LAR) parameters, extracted from a given block of speech, are approximated through Gaussian interpolation between the most-steady frames detected by the HTD. This results in a smaller set of parameters which are encoded usi... View full abstract»

• ### Approximating spherical harmonic representation order

Publication Year: 1999, Page(s):462 - 463
| | PDF (236 KB)

A technique is presented for approximating the spherical harmonic representation error during analysis, which in turn can be applied to determine a reasonable representation order for spherical harmonic modelling. The order is estimated according to a selected final error value instead of it having to be set in advance. In this way the modelling process is automated View full abstract»

• ### Beat frequency generation up to 3.4 THz from simultaneous two-mode lasing operation of sampled-grating DBR laser

Publication Year: 1999, Page(s):472 - 474
Cited by:  Papers (9)  |  Patents (6)
| | PDF (372 KB)

Simultaneous two-mode lasing operation for 0.56-3.4 THz beat signal generation is achieved from a single sampled-grating DBR laser by simply controlling the bias current. A high autocorrelation modulation depth and >30 dB suppression of the other cavity modes is demonstrated View full abstract»

• ### Adaptive step-size minor component extraction algorithm

Publication Year: 1999, Page(s):443 - 444
Cited by:  Papers (4)
| | PDF (192 KB)

An information criterion is introduced for extracting the minor component associated with the covariance matrix of an input process. An adaptive stepsize learning algorithm (ASMCEX) is proposed. The analysis shows that the ASMCEX algorithm has an equilibrium point. The simulations show that the ASMCEX algorithm can improve the convergence speed significantly View full abstract»

• ### Chaos in spacecraft power systems

Publication Year: 1999, Page(s):510 - 511
Cited by:  Papers (4)
| | PDF (152 KB)

A simple model of a spacecraft DC power system is investigated using the techniques of nonlinear dynamics. Limit cycles, coexisting attractors and chaos are observed. Chaos is confirmed by a positive Lyapunov exponent. The results have implications for reliable spacecraft engineering View full abstract»

• ### Semiconductor monolithic add-drop multiplexer using a grating switch integrated with coupler structure

Publication Year: 1999, Page(s):489 - 491
Cited by:  Papers (1)
| | PDF (328 KB)

A semiconductor monolithic add-drop multiplexer is proposed. An electrically tunable grating switch is monolithically integrated with multimode interference couplers and wavelength selective add-drop multiplexing is achieved in this structure for the first time. The power penalty is as small as 2 dB View full abstract»

• ### Using space-time TCM with rotated constellations for transmission over mobile communications channels

Publication Year: 1999, Page(s):454 - 456
Cited by:  Papers (3)  |  Patents (3)
| | PDF (336 KB)

Space-time trellis coded modulation is combined with a rotated signal set for transmission in mobile communication channels. Two systems are proposed and their performances simulated over slow selective fading channels View full abstract»

• ### TLM coefficients with distributed losses

Publication Year: 1999, Page(s):460 - 462
| | PDF (352 KB)

In TLM modelling of lossy systems, instead of concentrating losses in lumped resistors or stubs, an attempt is made to model the losses as distributed, in the connect' or propagate' stage, while leaving the scattering lossless. TLM transmission and reflection coefficients are derived using a novel, distributed, quasi-black box approach. The coefficients agree with those from lumped resistor anal... View full abstract»

• ### Optimal spreading sequence design based on PR-QMF theory

Publication Year: 1999, Page(s):447 - 448
Cited by:  Papers (2)
| | PDF (204 KB)

Based on filter bank theory, a new scheme for spreading sequence generation is proposed for direct sequence code division multiple access (DS-CDMA) systems. It is shown that optimal spreading sequences produce much less multiple access interference (MAI) than Gold codes with comparable lengths View full abstract»

• ### 22 GHz monolithically integrated oscillator in silicon bipolar technology

Publication Year: 1999, Page(s):438 - 439
Cited by:  Papers (7)
| | PDF (232 KB)

A monolithically integrated oscillator with a tuning range of 19.5-23 GHz is presented. The circuit uses on-chip spiral inductors and achieves a phase noise of -91 dBc/Hz at an offset of 1 MHz. It is manufactured in a 0.5 μm production-near silicon bipolar technology with fT and fmax of 50 GHz. The oscillator consumes 18.5 mA at a supply voltage of 3.3 V View full abstract»

• ### TE-pass and TM-pass waveguide polarisers with buried birefringent polymer

Publication Year: 1999, Page(s):471 - 472
Cited by:  Papers (6)
| | PDF (264 KB)

TE-pass and TM-pass waveguide polarisers in polymer waveguides using a buried layer of highly birefringent polyimide are presented. The two polarisers are fabricated based on a consistent process to insert polyimide for the buried ribs in TE-pass polarisers and for lateral cladding in TM-pass polarisers: respectively. Polarisation extinction ratios of 35 and 40 dB are obtained for the TE-pass and ... View full abstract»

• ### Experimental analysis of transient current testing based on charge observation

Publication Year: 1999, Page(s):441 - 443
Cited by:  Papers (7)
| | PDF (336 KB)

A test technique that uses the charge driven into the circuit computed from the transient power supply current is analysed. Experimental data are provided concerning the merits of this technique and its effectiveness at detecting open defects that do not increase the power consumption (those that cannot be detected with IDDQ) View full abstract»

• ### Suppression of reverse-short-channel effect in sub-0.1 μm n-MOSFETs with Sb S/D implantation

Publication Year: 1999, Page(s):508 - 509
Cited by:  Papers (4)  |  Patents (2)
| | PDF (220 KB)

A study is presented into the reverse-short-channel effect (RSCE) for Sb S/D ion implantation at 10 keV. A high impurity concentration is found to reduce interstitial movement in the channel, which restricts the level RSCE at short-channel lengths. The interstitials can be healed by thermal treatment at 850°C directly after ion implantation, resulting in the suppression of the RSCE View full abstract»

• ### Quarter Tbit/s (25×10 Gbit/s) over 9288 km WDM transmission experiment using nonlinear supported RZ pulse in higher order dispersion managed line

Publication Year: 1999, Page(s):488 - 489
Cited by:  Papers (4)  |  Patents (3)
| | PDF (232 KB)

It is experimentally shown that RZ pulse transmission without significant spectral broadening over a wide wavelength range is possible in higher order dispersion managed fibre spans. The use of this technique, together with wideband fibre dispersion and optical passband management techniques, yields long-distance WDM transmission with the largest capacity of 25×10 Gbit/s over 9000 km View full abstract»

• ### Wavelet based watermarking method for digital images using the human visual system

Publication Year: 1999, Page(s):466 - 468
Cited by:  Papers (27)  |  Patents (3)
| | PDF (332 KB)

A wavelet based multiresolution watermarking method using the human visual system (HVS) is proposed, with the number of watermarks embedded proportional to the energy contained in each band. Experiments show that the proposed three-level wavelet based watermarking method is robust to some attacks such as, for example, joint photographic experts group (JPEG) compression, smoothing, cropping and col... View full abstract»

• ### Multiwaveguide SOA for increased saturation power without noise penalty

Publication Year: 1999, Page(s):485 - 486
Cited by:  Papers (1)  |  Patents (1)
| | PDF (212 KB)

The authors present a new semiconductor optical amplifier (SOA) concept. The multiwaveguide SOA (MWG-SOA), which associates N parallel SOAs and yields a 10 log(N) dB saturation power increase without noise penalty, for the same small-signal gain as each single SOA. The MWG-SOA concept is experimentally validated View full abstract»

• ### Fabrication of high-mobility Ge p-channel MOSFETs on Si substrates

Publication Year: 1999, Page(s):503 - 504
Cited by:  Papers (1)  |  Patents (72)
| | PDF (236 KB)

The first fabrication of Ge p-channel MOSFETs (p-MOSFETs) on Si substrates is reported. A CMOS compatible process based on relaxed Ge layers grown on Si(111) substrates by surfactant mediated epitaxy (SME) was used. The non-optimised low temperature process yielded normally-off Ge p-MOSFETs with record channel drift mobilities of 430 cm2/Vs View full abstract»

## Aims & Scope

Electronics Letters is internationally renowned for its rapid communication of new developments and emerging topics across the broad and interdisciplinary field of modern electronics and electrical engineering.

Full Aims & Scope

## Meet Our Editors

Editors-in-Chief

Professor Chris Toumazou
Director of the Biomedical Institute
Imperial College, London, UK

Professor Ian White
Head of Photonics Research
University of Cambridge, UK