Online ISSN
1350-911X
Print ISSN
0013-5194
Electronics Letters
Volume 24, Issue 11, 26 May 1988
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Volume 24, Issue 11
26 May 1988
Bidirectional multichannel 1.44 Gbit/s lightwave distribution system using subcarrier multiplexing
- Author(s): T.E. Darcie ; P.P. Iannone ; J.R. Talman ; C.A. Burrus ; T.A. Baker
- Source: Electronics Letters, Volume 24, Issue 11, p. 649 –650
- DOI: 10.1049/el:19880439
- Type: Article
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We demonstrate a bidirectional lightwave distribution system that uses subcarrier multiplexing to transmit data to eight nodes from a single head-end laser. Data for each node (180 Mbit/s) and return data (45 Mbit/s digital video) are transmitted as FSK subcarriers, between 2.5 and 5.0 GHz. Penalties from laser nonlinearities, interchannel interference or bidirectional transmission are negligible.
Constructing new perfect binary arrays
- Author(s): J. Jedwab and C. Mitchell
- Source: Electronics Letters, Volume 24, Issue 11, p. 650 –652
- DOI: 10.1049/el:19880440
- Type: Article
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Only a small number of different sizes are known for which there exist two-dimensional perfect binary arrays. Construction methods are given which generate new two-dimensional perfect binary arrays, four of which are larger than any previously reported.
Resonantly enhanced two-wave mixing via population pulsations in semiconductor laser amplifiers
- Author(s): M.W. McCall and K.A. Shore
- Source: Electronics Letters, Volume 24, Issue 11, p. 652 –653
- DOI: 10.1049/el:19880441
- Type: Article
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We demonstrate theoretically the existence of enhanced probe gain via population pulsations in nearly degenerate two-wave mixing in a semiconductor amplifier. The enhancement arises from the injection current modulation frequency coinciding with the pump/probe detuning. Probe saturation is shown to occur in less than 10 μm cavity length.
Radiation characteristics of a waveguide-excited short backfire-fed parabolic reflector operating in Q-band
- Author(s): P.S. Kooi ; M.S. Leong ; Chandra
- Source: Electronics Letters, Volume 24, Issue 11, p. 653 –654
- DOI: 10.1049/el:19880442
- Type: Article
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The letter presents measured results at 31–38 GHz of the radiation characteristics of a 0.252 m diameter parabolic dish fed at the prime focus by a short backfire antenna. The feed consists of an experimentally optimised design of a short backfire antenna, having a conical main reflector of 15° slant angle. The measured radiation patterns of the reflector system generally agree quite well with the prediction based on aperture field integration.
Novel sampling technique for digital video demultiplexing, descrambling and channel selection
- Author(s): D.W. Faulkner ; D.M. Russ ; D. Douglas ; P.J. Smith
- Source: Electronics Letters, Volume 24, Issue 11, p. 654 –656
- DOI: 10.1049/el:19880443
- Type: Article
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The letter describes a novel method of distributing a large number of digital video channels over a passive optical fibre network, while allowing the use of baseband binary receive equipment. The synchronous TDM is sampled, and receive channels are descrambled using a programmable delay-lock loop.
Gain enhancement of microstrip antennas with overlaying parasitic directors
- Author(s): R.Q. Lee and K.F. Lee
- Source: Electronics Letters, Volume 24, Issue 11, p. 656 –658
- DOI: 10.1049/el:19880444
- Type: Article
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The gain characteristics of rectangular microstrip antennas with one and two overlaying parasitic directors have been investigated experimentally. Results indicate that, when properly spaced, the parasitic directors can enhance the gain (dB) and reduce the beamwidth of the antenna by a factor of two or better.
Evaluation of scalar products of repeated integrals of a function with rational Laplace transform
- Author(s): L.C. Calvez ; P. Vilbe ; P. Brehonnet
- Source: Electronics Letters, Volume 24, Issue 11, p. 658 –659
- DOI: 10.1049/el:19880445
- Type: Article
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An efficient method for evaluating scalar products of repeated integrals of a function with a known rational Laplace transform is presented. Factoring of the denominator is not required. An immediate promising application is determination of the positions of poles with a view to model reduction.
New adaptive normalised lattice algorithm for recursive filters
- Author(s): M. Tummala
- Source: Electronics Letters, Volume 24, Issue 11, p. 659 –661
- DOI: 10.1049/el:19880446
- Type: Article
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A new adaptive algorithm is presented for updating the parameters of normalised lattice structured recursive filters. The normalised lattice can be represented in the form of CORDIC blocks by converting the reflection factors into trigonometric functions. The LMS based algorithm actually updates the arguments of these trigonometric functions, and requires fewer computations than an earlier reported algorithm.
Microwave lowpass filters using hybrid uniplanar structures
- Author(s): J. Palacios and S. Toutain
- Source: Electronics Letters, Volume 24, Issue 11, p. 661 –662
- DOI: 10.1049/el:19880447
- Type: Article
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The letter deals with the design of lowpass filters using hybrid uniplanar structures. To minimise the spurious response levels, a new compact quasi-lumped element concept is proposed. For a 2.5 GHz cutoff frequency filter, experimental data show that spurious responses are lower than 20 dB up to 18 GHz.
Four-port fibre-optic ring resonator
- Author(s): P.A. Davies and G. Abd-El-Hamid
- Source: Electronics Letters, Volume 24, Issue 11, p. 662 –663
- DOI: 10.1049/el:19880448
- Type: Article
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A novel device is described, formed by taking one of the outputs of a 3 × 3 fused optical coupler back to one of the inputs to form a fibre optic ring resonator with two inputs and two outputs. The device can be used for narrowband wavelength division multiplexing and for switching of optical signals.
Straightforward derivation of boundary conditions on sheet simulating an anisotropic thin layer
- Author(s): M. Idemen
- Source: Electronics Letters, Volume 24, Issue 11, p. 663 –665
- DOI: 10.1049/el:19880449
- Type: Article
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Approximate boundary conditions on a sheet simulating an anisotropic thin layer are derived using previously derived general boundary relations. The method depends on the concept of distribution and does not require complicated mathematical representations or unproved equivalence principles.
Gabor's expansion of an aperture field in exponential elementary beams
- Author(s): P.D. Einziger
- Source: Electronics Letters, Volume 24, Issue 11, p. 665 –666
- DOI: 10.1049/el:19880450
- Type: Article
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Gabor's expansion of an aperture field in a discrete two-dimensional superposition of Gaussian elementary beams is extended here to incorporate exponential beams. The resultant expansion scheme has an advantage over the commonly used Gaussian beam representation in situations involving an exponential aperture distribution such as the modal field in a thin slab laser amplifier.
Monolithic millimetre-wave oscillator using a transmission line periodically loaded by QWITT diodes
- Author(s): V.P. Kesan ; A. Mortazawi ; D.P. Neikirk ; T. Itoh
- Source: Electronics Letters, Volume 24, Issue 11, p. 666 –667
- DOI: 10.1049/el:19880451
- Type: Article
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A small-signal analysis of a travelling-wave structure implemented by periodically loading a parallel-plate waveguide with either resonant tunnelling or QWITT diodes is presented. A small-signal equivalent circuit is used to determine the diode impedance as a function of frequency. The periodicity of the structure, i.e. the distance between adjacent diodes, determines the oscillation (resonant) frequency of the circuit. The analysis shows that change in the oscillation frequency through variation in the design width and thickness of the waveguide is minimal. The physical dimensions of the waveguide facilitate monolithic fabrication of the oscillator circuit.
Multigigabit multiplexer design
- Author(s): L. Rønn
- Source: Electronics Letters, Volume 24, Issue 11, p. 667 –669
- DOI: 10.1049/el:19880452
- Type: Article
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The letter describes a time division multiplexer design for multi-Gbit/s operation. The design is based on a delay line travelling-pulse concept using dual-gate GaAs MESFETs. The function of the multiplexer is verified by both implementation of a 4:1 multiplexer device and by mw SPICE simulations.
Measurement of a modulated DFB laser spectrum using gated delayed self-homodyne technique
- Author(s): D.M. Baney and W.V. Sorin
- Source: Electronics Letters, Volume 24, Issue 11, p. 669 –670
- DOI: 10.1049/el:19880453
- Type: Article
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The mixing of a modulated DFB laser with a CW local oscillator can be achieved with a single laser by using a gated modulation technique combined with an appropriate optical delay. Frequency chirp measurements up to ±22 GHz are demonstrated using this technique.
Blank and burst transmission of data over active speech channels
- Author(s): W.C. Wong and D.J. Goodman
- Source: Electronics Letters, Volume 24, Issue 11, p. 670 –672
- DOI: 10.1049/el:19880454
- Type: Article
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To increase the capacity of blank and burst transmission of control information in cellular communication systems, we explore the application of a speech segment reconstruction technique. The transmitter selects a blanking interval on the basis of a segment classification measure, while the receiver replaces the missing speech with an estimate based on previously received speech. Using this approach, approximately 3.2 data bursts per second, each lasting 16 ms, may be sent without degrading speech quality.
Novel single-mode, grating WDM device based network
- Author(s): A. Lord and J.M. Boggis
- Source: Electronics Letters, Volume 24, Issue 11, p. 672 –674
- DOI: 10.1049/el:19880455
- Type: Article
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Experiments on a commercial grating WDM device show that it can be used as the core element in a passive, complete routing network, allowing secure communication between all system users. A system is configured to demonstrate this potential use.
Field-effect transistor with diphthalocyanine thin film
- Author(s): C. Clarisse ; M.T. Riou ; M. Gauneau ; M. le Contellec
- Source: Electronics Letters, Volume 24, Issue 11, p. 674 –675
- DOI: 10.1049/el:19880456
- Type: Article
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A field effect transistor has been fabricated with organic semiconductors: scandium diphthalocyanine and nickel phthalocyanine. The electrical characteristics are studied in air atmosphere. The influence of the diphthalocyanine film thickness has been detected.
Bidirectional beam propagation method
- Author(s): P. Kaczmarski and P.E. Lagasse
- Source: Electronics Letters, Volume 24, Issue 11, p. 675 –676
- DOI: 10.1049/el:19880457
- Type: Article
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The formalism of the beam propagation method (BPM) is extended in a self-consistent way so as to allow the analysis of reflections in waveguiding structures containing longitudinal discontinuities.
Jitter accumulation in a simulated 591.2 Mbit/s, 6000 km optical transmission system
- Author(s): B.I. McNally ; S.F. Carter ; S.D. Walker
- Source: Electronics Letters, Volume 24, Issue 11, p. 676 –678
- DOI: 10.1049/el:19880458
- Type: Article
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An equivalent-time jitter synthesis experiment is described which allows laboratory evaluation of transoceanic regenerated optical transmission systems. Results are reported for the systematic timing jitter accumulation obtained over a 591.2 Mbit/s, 6000 km route derived from the simulated concatenation of 60 regenerated sections.
Image registration using Fermat transforms
- Author(s): C. Morandi ; F. Piazza ; A. Dolcetti
- Source: Electronics Letters, Volume 24, Issue 11, p. 678 –680
- DOI: 10.1049/el:19880459
- Type: Article
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Binary boundary maps are obtained by edge detection, then their relative translation is determined by conventional crosscorrelation computed by Fermat transform. Use of boundary maps emphasises edges and sharp discontinuities, while rejecting disturbances related to nonuniform illumination, thus avoiding the costly normalisation step. Use of integer arithmetic allows significant savings in computatio
Improved cavity model parameters for calculation of resonant frequency of rectangular microstrip antennas
- Author(s): N.M. Martin
- Source: Electronics Letters, Volume 24, Issue 11, p. 680 –681
- DOI: 10.1049/el:19880460
- Type: Article
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Models for the resonant frequency proposed by other authors are shown to produce misleading results for frequencies greater than about 3 GHz. However, a cavity model with a novel empirically determined edge extension parameter provides calculated frequencies within 2% of measurements for antennas operating between 600MHz and 5 GHz.
Eleven-bit parity generator with a single, vertically integrated resonant tunnelling device
- Author(s): A.A. Lakhani ; R.C. Potter ; H.S. Hier
- Source: Electronics Letters, Volume 24, Issue 11, p. 681 –683
- DOI: 10.1049/el:19880461
- Type: Article
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A vertically integrated diode (VID) with five negative differential resistance regions has been developed by stacking five resonant tunnelling structures. This device can be used for processing both analogue and digital signals. An 11-bit parity checker was demonstrated using the VID. In this approach, a single device replaced a large number of exclusive-OR gates in a conventional parity checker.
Linear resonator in photorefractive BSO with two pump beams
- Author(s): D.R. Erbschloe and L. Solymar
- Source: Electronics Letters, Volume 24, Issue 11, p. 683 –684
- DOI: 10.1049/el:19880462
- Type: Article
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A linear resonator using a new amplification mechanism in BSO is reported. The gain can be optimised for a particular frequency detuning of one pump beam.
Effect of external cavity semiconductor laser phase noise on a DPSK heterodyne optical receiver
- Author(s): S. Betti ; G. de Marchis ; E. Iannone ; A. Martellucci
- Source: Electronics Letters, Volume 24, Issue 11, p. 684 –685
- DOI: 10.1049/el:19880463
- Type: Article
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The effect of an external cavity semiconductor laser on the performance of a DPSK heterodyne optical system is evaluated. The actual shape of the frequency fluctuation spectral density of the optical source is taken into account, and a comparison with a PSK coherent heterodyne system is carried out.
Ge-Si/Si infra-red, zone-folded superlattice detectors
- Author(s): T.P. Pearsall ; E.A. Beam ; H. Temkin ; J.C. Bean
- Source: Electronics Letters, Volume 24, Issue 11, p. 685 –687
- DOI: 10.1049/el:19880464
- Type: Article
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Superlattice photovoltaic waveguide detectors have been fabricated and tested with a strained-layer superlattice active region of four alternating atomic monolayers of Ge and Si. The infra-red spectral response extends to 1.4 μm. The peak of the optical response is shifted toward the visible relative to Ge-Si alloy detectors of a similar average composition.
Barrier height enhancement of InP-based n-Ga0.47In0.53As Schottky-barrier diodes grown by molecular beam epitaxy
- Author(s): J.H. Kim ; S.S. Li ; L. Figueroa
- Source: Electronics Letters, Volume 24, Issue 11, p. 687 –689
- DOI: 10.1049/el:19880465
- Type: Article
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Barrier height enhancement of an InP-based p+n-Ga0.47In0.53As Schottky diode grown by MBE has been demonstrated for infra-red photodetector applications. A barrier height of 0.35eV for n-Ga0.47In0.53As Schottky barrier diodes, was increased to the effective barrier height of 0.55eV, with a p+-Ga0.47In0.53As surface layer of 30 nm thick. The results show a reverse leakage current density of 1.5 × 10−3 A/cm2 and a junction capacitance of 0.3 pF, which are comparable to those of p-Ga0.47In0.53As Schottkybarrier diodes at a reverse bias voltage of 5 V.
Demonstration of an eight-element time-division multiplexed interferometric fibre sensor array
- Author(s): A.D. Kersey ; K.L. Dorsey ; A. Dandridge
- Source: Electronics Letters, Volume 24, Issue 11, p. 689 –691
- DOI: 10.1049/el:19880466
- Type: Article
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We report the demonstration of an eight-element multiplexed interferometric fibre-optic sensor array based on timedivision addressing. The configuration gives rise to intrinsic optical crosstalk between sensor elements of the system, which is analysed and compared with experimental results.
Silicon on quartz by solid-state diffusion bonding (SSDB) technology
- Author(s): X.-L. Xu ; J. Zhan ; Q.-Y. Tong
- Source: Electronics Letters, Volume 24, Issue 11, p. 691 –692
- DOI: 10.1049/el:19880467
- Type: Article
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Silicon wafer and quartz have been successfully bonded together by a two-step thermal treatment process. SIMS measurements shows that after molecular surface activated solvent treatment, the amount of OH on the silicon or quartz surface, which is essential to the first step (low-temperature) bonding strength, is one order of magnitude higher than that on the original silicon or quartz surface. After a high-temperature (850–1250°C) solid-state diffusion process, the bonding strength between silicon and quartz is greatly increased to 150–185 kg/cm2. The material and electrical properties of the silicon on quartz substrate compares favourably with those of the bulk silicon wafer.
Modelling of CSMA/CA protocol by simulation
- Author(s): A.M. Glass ; R.L. Brewster ; N.K. Abdulaziz
- Source: Electronics Letters, Volume 24, Issue 11, p. 692 –694
- DOI: 10.1049/el:19880468
- Type: Article
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A simulation model of the CSMA/CA protocol is presented. The model uses the simulation language SLAM II. The two cases of nonpersistent and slotted nonpersistent CSMA/CA protocols are considered. The results obtained show a good performance with regard to the throughput against offeredload characteristics of the protocol.
Continuous multidestination ARQ schemes for high error-rate channels
- Author(s): Y.J. Cho and C.K. Un
- Source: Electronics Letters, Volume 24, Issue 11, p. 694 –695
- DOI: 10.1049/el:19880469
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The letter considers three relatively simple schemes that can effectively be used for multidestination communications using high error-rate channels. The advantage of the schemes over the widely known multidestination go-back-N scheme becomes more evident as the number of destination stations increases.
High-speed 1.3 μm GaInAsP p-substrate buried-crescent lasers with semi-insulating Fe/Ti-doped InP current blocking layers
- Author(s): C.E. Zah ; C. Caneau ; S.G. Menocal ; F. Favire ; T.P. Lee ; A.G. Dentai ; C.H. Joyner
- Source: Electronics Letters, Volume 24, Issue 11, p. 695 –697
- DOI: 10.1049/el:19880470
- Type: Article
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High-speed 1.3 μm GaInAsP buried-crescent lasers were made with a MOVPE-grown semi-insulating Fe/Ti-doped InP current-blocking layer on p-InP substrate. Ti, a deeplevel donor, was used to compensate Zn outdiffusion from the buffer layer during the LPE regrowth. Devices with broad area contacts had a modulation bandwidth of 11 GHz, a low threshold current of 11 mA, and an output power of 23 mW per facet.
High-frequency (>1 MHz) convertors for induction heating applications
- Author(s): S. Hinchliffe and L. Hobson
- Source: Electronics Letters, Volume 24, Issue 11, p. 697 –698
- DOI: 10.1049/el:19880471
- Type: Article
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There are many applications in high frequency induction heating (1–10MHz) where small, solid state supplies would be advantageous over present thermionic valve equipment. The letter details the work being undertaken at Loughborough University to increase the frequency of operation of solid-state induction heating power sources above 1 MHz.
Reproducible fabrication of AlGaAs/GaAs circular buried heterostructure (CBH) surface-emitting lasers with low thresholds
- Author(s): S. Kinoshita ; K. Morito ; F. Koyama ; K. Iga
- Source: Electronics Letters, Volume 24, Issue 11, p. 699 –700
- DOI: 10.1049/el:19880472
- Type: Article
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The fabrication process for circular buried-heterostructure surface-emitting lasers has been improved to increase the uniformity of the active region diameter. Circular mesas of 8 μm diameter can now be consistently prepared and lowthreshold surface-emitting lasers (30–60 mA at room temperature pulsed conditions) are obtained.
Performance of a voice/data multiplexer with ARQ schemes
- Author(s): C.K. Jeong and C.K. Un
- Source: Electronics Letters, Volume 24, Issue 11, p. 700 –702
- DOI: 10.1049/el:19880473
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We consider an integrated voice/data multiplexer, in which data packets are buffered under the control of an ARQ retransmission scheme, while voice signals are transmitted in real time. To investigate the performance of such a system, we use a Markov renewal sequence model and calculate mean data packet delay. Analytical results are validated by simulation.
DC and microwave characteristics of modulation doped Ga0.47In0.53As/InP HFET
- Author(s): A. Shahar ; M.D. Feuer ; U. Koren ; B.I. Miller
- Source: Electronics Letters, Volume 24, Issue 11, p. 702 –703
- DOI: 10.1049/el:19880474
- Type: Article
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The DC and microwave performance of modulation doped GaInAs/InP HFETs (heterostructure FET), grown by atmospheric pressure organometallic vapour phase epitaxy is reported. An extrinsic transconductance of 300 mS/mm and a best value of the cutoff frequency, Fr = 14.1 GHz in a 1.5 μm gate device was measured at room temperature. Improved performance of the Schottky gate device is obtained using an Au gate on the InP/GaInAs heterostructure layers. A low access resistance of 3 Ωmm is obtained using a self-aligned technique with high conductivity n+-GaInAs top layers. ty n+-GaInAs top layers.
Seasonal variation of crosspolarisation statistics observed at CS-2 experimental Earth station
- Author(s): Y. Maekawa ; N.S. Chang ; A. Miyazaki ; T. Segawa
- Source: Electronics Letters, Volume 24, Issue 11, p. 703 –705
- DOI: 10.1049/el:19880475
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Crosspolarisation statistics obtained by the CS-2 beacon signal (19.45 GHz) are compared with the CCIR (1986) prediction. The observation shows a notable seasonal variation, although the overall long-term statistics agree well with the prediction. Simultaneous radar measurements suggest that as bright band heights become lower, effects of ice are increased in the statistics.
4.8 kbit/s data transmission over 16 kbit/s digital mobile radio channel
- Author(s): S. Ito ; T. Miki ; F. Adachi
- Source: Electronics Letters, Volume 24, Issue 11, p. 705 –706
- DOI: 10.1049/el:19880476
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A channel coding is described for 4.8 kbit/s data transmission in a digital mobile radio using a 16 kbit/s radio channel. The channel coding is a combination of time diversity reception and forward error correction. Laboratory simulation and field experimental results using 1.5 GHz carrier frequency are presented.
Fast CELP coder using Givens bidiagonalisation
- Author(s): T.F. Thorpe
- Source: Electronics Letters, Volume 24, Issue 11, p. 706 –708
- DOI: 10.1049/el:19880477
- Type: Article
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CELP speech coders give good performance but require considerable computational power. Earlier work showed how singular value decomposition can be used to speed up the calculations required for codebook search in the CELP. The bidiagonal decomposition proposed here is simpler and results in a fast algorithm with fixed running time.
GaAs MESFETs with nonalloyed ohmic contacts: technology and performance
- Author(s): A. Paccagnella ; C. Canali ; G. Donzelli ; E. Zanoni ; L.C. Wang ; S.S. Lau
- Source: Electronics Letters, Volume 24, Issue 11, p. 708 –709
- DOI: 10.1049/el:19880478
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GaAs MESFETs with nonalloyed ohmic contacts, achieved through a solid phase reaction of a Ge/Pd/GaAs (xtl) structure, have been realised and tested at DC and RF. Their contact resistivity and electrical performances are better than those of similar devices with conventional AuGeNi ohmic contacts.
Samarium3+-doped glass laser operating at 651 nm
- Author(s): M.C. Farries ; P.R. Morkel ; J.E. Townsend
- Source: Electronics Letters, Volume 24, Issue 11, p. 709 –711
- DOI: 10.1049/el:19880479
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Laser emission has been observed in a samarium3+-doped silica optical fibre in a Fabry-Perot-type laser cavity. The emission is centred on 651 nm and corresponds to stimulated transitions from the 4G5/2 level to the 6H9/2 level. The fluorescence and absorption associated with the metastable level are seen to be unusually narrow (3nm FWHM) for a trivalent rare earth in a disordered glass structure. The laser has operated in CW and Q-switched modes when pumped with 488 nm light at room temperature.
Automatic edge extraction using locally adaptive threshold
- Author(s): G.S. Jung and R.-H. Park
- Source: Electronics Letters, Volume 24, Issue 11, p. 711 –712
- DOI: 10.1049/el:19880480
- Type: Article
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We describe an automatic edge extraction algorithm using a new edge operator called the EK edge operator, and a locally adaptive threshold subject to brightness and gradient value in a picture. The proposed algorithm is capable of extracting one-pixel-thick edges and giving a rather pleasing representation of the original grey-level picture. This algorithm is compared to the well known Sobel gradient operator and Keskes' zero-crossing operator.
Performance analysis of a voice/data multiplexer for a nonfixed number of voice calls
- Author(s): S.R. Kim and C.K. Un
- Source: Electronics Letters, Volume 24, Issue 11, p. 712 –713
- DOI: 10.1049/el:19880481
- Type: Article
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The letter formulates the load variation of voice traffic in a voice/data multiplexer with a finite buffer when the number of voice calls is not fixed, and analyses its performance.
Comment: Existence of one-dimensional perfect binary arrays
- Author(s): C. Mitchell
- Source: Electronics Letters, Volume 24, Issue 11, page: 714 –714
- DOI: 10.1049/el:19880482
- Type: Article
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Through-wafer optical interconnection coupling characteristics
- Author(s): L.A. Hornak
- Source: Electronics Letters, Volume 24, Issue 11, p. 714 –715
- DOI: 10.1049/el:19880483
- Type: Article
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Both the optical coupling and resulting optical crosstalk characteristics for LED-based through-wafer optical interconnections have been measured within a simulated stacked wafer environment. Using integrated SiO2 Fresnel phase plate lens arrays, a nearly 4:1 improvement in received signal was noted over the configuration without lenses. Interchannel crosstalk measurements indicate that from an optical standpoint, high interconnect densities (250 μm pitch) are obtainable with reasonable noise margins over a range of distances of interest for stacked wafer architectures.
CPFSK coherent optical receivers: impact of IF bandwidth and laser phase noise
- Author(s): G. Jacobsen and L.G. Kazovsky
- Source: Electronics Letters, Volume 24, Issue 11, p. 715 –717
- DOI: 10.1049/el:19880484
- Type: Article
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A detailed theoretical model for narrowband CPFSK receivers is presented. It accounts for the influence of IF bandwidth on the signal voltage, non-Gaussian statistics of the output noise, correlation between noise samples stemming from limited IF bandwidth, and the impact of laser phase noise. It is found that the IF bandwidth needed to avoid intersymbol interference is 2.2 times the bit rate for a modulation index of 1; it is higher for other modulation index values. The bit error ratio is within 1 dB of the shot noise limit for the modulation index of 1.
High-current, planar-doped pseudomorphic hemts Ga0.4In0.6As/Al0.48In0.52As HEMTs
- Author(s): A. Fathimulla ; H. Hier ; J. Abrahams
- Source: Electronics Letters, Volume 24, Issue 11, p. 717 –718
- DOI: 10.1049/el:19880485
- Type: Article
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The letter reports the first successful growth and fabrication of high-performance, planar-doped pseudomorphic GaInAs/AlInAs HEMTs. Hall mobilities as high as 11900cm2/Vs (300 K) with sheet-electron concentrations of 2.4 × 1012cm−2 were measured for the heterostructures. A drain-saturation current of 1 A/mm, a transconductance of 420mS/mm, and an extrapolated f1 of 64 GHz were achieved in a 0.5 μm gate-length HEMT.
Comment: Fundamental error of recent coupled mode formulations
- Author(s): W. Streifer
- Source: Electronics Letters, Volume 24, Issue 11, p. 718 –719
- DOI: 10.1049/el:19880486
- Type: Article
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Reply: Coupled mode theory neglects polarisation phenomena
- Author(s): A.W. Snyder ; A. Ankiewicz ; A. Altintas
- Source: Electronics Letters, Volume 24, Issue 11, p. 720 –721
- DOI: 10.1049/el:19880487
- Type: Article
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