By Topic

# 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»

• ### Small core high NA Pr-doped As-glass fibres for efficient 1.3 μm amplification

Publication Year: 1999, Page(s):496 - 497
| | PDF (216 KB)

Singlemode fibres for optical 1.3 μm amplification with 760 wt.ppm Pr3+ have been prepared for the first time in the As-S system. The fibres show low losses in the pump and signal region, good fluorescence behaviour and good mechanical properties View full abstract»

• ### Fibre optic microwave and millimetre-wave filter with high density sampling and very high sidelobe suppression using subnanometre optical spectrum slicing

Publication Year: 1999, Page(s):494 - 496
Cited by:  Papers (25)  |  Patents (1)
| | PDF (344 KB)

The implementation of a transversal fibre optic RF filter based on subnanometre optical spectrum slicing is reported. The number of taps (34) and the sidelobe suppression (>35 dB) is the highest reported to date for filters based on this technology View full abstract»

• ### Wavelength-stabilised source of nearly transform limited optical pulses for 10 Gbit/s RZ transmission

Publication Year: 1999, Page(s):493 - 494
| | PDF (236 KB)

The generation of a 10 GHz train of 35 ps FWHM nearly transform-limited pulses using a distributed feed-back laser and a fibre grating is demonstrated. The externally modulated pulses propagated error-free up to 22000 km in a dispersion-managed soliton system 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»

• ### 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»

• ### 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»

• ### 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»

• ### Single-crystal ferroelectric microwave capacitor fabricated by separation by hydrogen implantation

Publication Year: 1999, Page(s):477 - 478
Cited by:  Papers (2)  |  Patents (8)
| | PDF (216 KB)

Microwave ferroelectric capacitors have been fabricated using separation by hydrogen ion implantation and transfer of a 500 nm thick single crystal SrTiO3 layer to an insulating glass substrate. The capacitor films are of high quality with a measured quality factor of nearly 100 at 10 GHz 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»

• ### Thin film vertical diffraction gratings fabricated using glancing angle deposition

Publication Year: 1999, Page(s):491 - 493
| | PDF (340 KB)

SiO thin film vertical diffraction gratings fabricated on Si substrates by the use of an advanced glancing angle deposition (GLAD) technique are demonstrated. Diffraction gratings with variable groove heights and variable grating periods ranging from 100 nm to 10 μm are fabricated in a one-step deposition process. Gratings fabricated with this technique have potential applications in integrated... View full abstract»

• ### “Black box” optical regenerator for RZ transmission systems

Publication Year: 1999, Page(s):480 - 481
Cited by:  Papers (8)  |  Patents (3)
| | PDF (212 KB)

A novel in-line regeneration scheme is proposed for any RZ system, based on periodic RZ/soliton/RZ conversion and synchronous modulation within a “black box”. The regenerator is shown theoretically to significantly increase transmission distance 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»

• ### 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»

• ### 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»

• ### Comparison of electro-optic effect between stoichiometric and congruent LiNbO3

Publication Year: 1999, Page(s):499 - 501
Cited by:  Papers (5)
| | PDF (336 KB)

Comparison of the electro-optic (EO) effect between stoichiometric and congruent lithium niobate (LiNbO3) crystals has been investigated using the Mach-Zehnder interferometer at 0.633 μm wavelength. Anisotropic changes of EO coefficients, r33 and r 13 have been found between the stoichiometric and congruent LiNbO3 crystals. The measured r33... 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»

• ### 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»

• ### Partial response continuous phase chirp modulation

Publication Year: 1999, Page(s):448 - 449
Cited by:  Papers (1)
| | PDF (208 KB)

A class of chirp modulation called partial response continuous phase chirp modulation is introduced by extending the length of the baseband pulse for more than one interval. Partial response chirp signals are constructed at finite numbers of states. Numerical results show that partial response chirp signals perform significantly better and they also have better spectral variations than the known c... 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»

• ### Noise figure improvement of optical gain clamped fibre amplifier by mid-point band reject filter for lasing light

Publication Year: 1999, Page(s):486 - 488
Cited by:  Papers (6)
| | PDF (324 KB)

A new configuration for improving the noise performance of an optical gain clamped erbium-doped fibre amplifier is proposed. The effect is also demonstrated by experimentally comparing the noise figure of the proposed configuration to that of the previously proposed configuration 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