Online ISSN
1350-911X
Print ISSN
0013-5194
Electronics Letters
Volume 14, Issue 9, 27 April 1978
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Volume 14, Issue 9
27 April 1978
Skeletonisation of binary patterns: a heuristic approach
- Author(s): R.N. Jones and M.C. Fairhurst
- Source: Electronics Letters, Volume 14, Issue 9, p. 265 –266
- DOI: 10.1049/el:19780180
- Type: Article
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p.
265
–266
(2)
Conventional algorithms which have been proposed for the skeletonisation of digital patterns or pictures suffer from basic problems (for example, endpoint identification, connectivity) deriving from the rigid application of fixed rules. This letter introduces a heuristic approach to the problem which overcomes such difficulties and may be tailored to suit different types of data.
A sequential regression algorithm for recursive filters
- Author(s): D. Parikh and N. Ahmed
- Source: Electronics Letters, Volume 14, Issue 9, p. 266 –268
- DOI: 10.1049/el:19780181
- Type: Article
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p.
266
–268
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A sequential regression (s.e.r.) algorithm is derived for recursive or infinite impulse response (i.i.r.) adaptive filters. Results pertaining to using the algorithm in a system-identification experiment are also included.
Least-mean-square (minimum integrated power loss ratio) lowpass filters with a pair of imaginary-axis zeros
- Author(s): P. Thajchayapong
- Source: Electronics Letters, Volume 14, Issue 9, p. 268 –270
- DOI: 10.1049/el:19780182
- Type: Article
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p.
268
–270
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If power is the main interest, then a class of filters with minimum integrated power loss ratio in the passband offers higher cutoff rate than the well known Butterworth filters. A technique is described to improve the cutoff rate further by introducing a pair of imaginary axis zeros, while the integrated power loss ratio in the passband is still kept at minimum. Other advantageous performances of the filters are also indicated.
Increasing the efficiency of roulette simulation of teletraffic
- Author(s): M.H. Ackroyd
- Source: Electronics Letters, Volume 14, Issue 9, page: 270 –270
- DOI: 10.1049/el:19780183
- Type: Article
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p.
270
(1)
A simple modification of the roulette method of teletraffic simulation is presented. At low traffic levels it may result in a reduction, by a factor of ten or more, of the computer time required to simulate a specified number of calls.
A note on volume holograms
- Author(s): M.P. Jordan and L. Solymar
- Source: Electronics Letters, Volume 14, Issue 9, p. 271 –272
- DOI: 10.1049/el:19780184
- Type: Article
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p.
271
–272
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A model describing the operation of volume phase holograms is studied. It is shown that due to hitherto disregarded effects the Bragg conditions are not automatically satisfied, and high efficiency of wave conversion may only be achieved under special circumstances.
GaAs m.e.s.f.e.t. technology and characteristics for optical communication systems
- Author(s): J.J.M. Dekkers ; W. Filensky ; H. Beneking
- Source: Electronics Letters, Volume 14, Issue 9, p. 272 –274
- DOI: 10.1049/el:19780185
- Type: Article
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p.
272
–274
(3)
For pulse regeneration applications GaAs m.e.s.f.e.t.s with low pinch-off voltages are desirable. The technology and the dependence of the input/output pulse width ratio on the bias voltage are described. The pulse behaviour of a two-stage sharpener is shown and the block diagram of an optical repeater station is proposed.
Star couplers using fused biconically tapered multimode fibres
- Author(s): Eric G. Rawson and Antonio B. Nafarrate
- Source: Electronics Letters, Volume 14, Issue 9, p. 274 –275
- DOI: 10.1049/el:19780186
- Type: Article
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p.
274
–275
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We report the fabrication and testing of 4-, 7-and 19-fibre fused biconical taper transmissive star couplers for use with single multimode fibres. Overall insertion losses on six couplers range from −1.3 dB to −2.6 dB. Losses are nearly independent of N, the number of fibres, but dispersion of the powers in the output fibres increases significantly with N.
Minimal order observers for linear functions of the state vector
- Author(s): S. Srinathkumar
- Source: Electronics Letters, Volume 14, Issue 9, p. 275 –277
- DOI: 10.1049/el:19780187
- Type: Article
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p.
275
–277
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The problem of estimating linear functions of a state vector in a multi-input/output system is considered. A simple lower bound on the observer order with arbitrary eigenvalues is established. Algorithms to construct minimal-order stable (or arbitrary dynamics) observers are also outlined.
Normalised frequency dependence of splice losses in single-mode optical fibres
- Author(s): Yasuji Murakami ; Iwao Hatakeyama ; Haruhiko Tsuchiya
- Source: Electronics Letters, Volume 14, Issue 9, p. 277 –278
- DOI: 10.1049/el:19780188
- Type: Article
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p.
277
–278
(2)
Simple formulas for splice losses have been derived by using the series expansion. The losses are proportional to the square of normalised axial or angular displacement. The coefficient is determined by only the normalised frequency. Normalised frequency dependence measurements of the splice losses show excellent agreement with the theory.
Annual and annual-worst-month statistics of fading on Earth satellite paths at 11.5 GHz
- Author(s): G. Brussaard and P.A. Watson
- Source: Electronics Letters, Volume 14, Issue 9, p. 278 –280
- DOI: 10.1049/el:19780189
- Type: Article
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p.
278
–280
(3)
Attenuation statistics from 19 site/years of 11.5 GHz radiometer measurements are presented for the European region. It is found that a factor between 6 and 7 is necessary to convert from annual-worst-month to yearly time percentages. A theoretical treatment is presented which shows excellent agreement with these results. Both the measurements and the analysis contradict a recent proposal for an upper bound of 4.41 on the conversion factor.
Multicomponent glass fibres with high numerical aperture
- Author(s): S. Takahashi ; S. Mitachi ; S. Shibata ; M. Yasu
- Source: Electronics Letters, Volume 14, Issue 9, p. 280 –281
- DOI: 10.1049/el:19780190
- Type: Article
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p.
280
–281
(2)
Multicomponent glass is suited for the preparation of high numerical aperture (n.a.) fibres which may be used in short-distance applications. Low loss of 20dB/km fibres have been produced with a n.a. of 0.53. Core glass having high refractive index has been prepared by using the additives of BaO and GeO2 which are hardly harmful to the intrinsic absorption loss.
Third-order intermodulation distortion in microwave amplifier
- Author(s): K.K. Agarwal and Y.L. Kuo
- Source: Electronics Letters, Volume 14, Issue 9, p. 282 –283
- DOI: 10.1049/el:19780191
- Type: Article
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p.
282
–283
(2)
Third-order intermodulation distortions of a microwave GaAs f.e.t. amplifier are analysed using a simple nonlinear model for the device. If the amplifier has strong feedback at low frequencies, the second-order interactions may dominate and degrade the third-order distortions. Solutions are presented to eliminate this distortion degradation. The analysis is very well substantiated by measurements.
Multimode 2 × 2 optical crossbar switch
- Author(s): R.A. Soref and D.H. McMahon
- Source: Electronics Letters, Volume 14, Issue 9, p. 283 –284
- DOI: 10.1049/el:19780192
- Type: Article
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p.
283
–284
(2)
A monolithic electro-optical 2 × 2 crossbar has been developed. The multimode network consists of channel waveguides and four crosspoint switches integrated in a LiTaO3 plate. Matrix switching loss was 11 dB and crosstalk was −16 dB for TM-polarised 0.07-n.a. light.
Transient and frequency responses of systems with time delays
- Author(s): M.J. Underhill
- Source: Electronics Letters, Volume 14, Issue 9, p. 284 –286
- DOI: 10.1049/el:19780193
- Type: Article
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p.
284
–286
(3)
For systems containing time delays, root locus methods can locate any Laplace transform closed-loop poles. L'Hôpital's rule is shown to give exact residue values for any of the infinity of closed-loop poles. The transient or frequency response can then be estimated from dominant poles and their residues.
Solution of the discrete regulator problem using the sign matrix function
- Author(s): A. Halbersberg and Y. Bar-ness
- Source: Electronics Letters, Volume 14, Issue 9, p. 286 –287
- DOI: 10.1049/el:19780194
- Type: Article
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p.
286
–287
(2)
The sign matrix function algorithm is used to solve the discrete Riccati equation which arises in the optimisation problem of the discrete regulator with quadratic cost criterion.
An improved switched-capacitor integrator
- Author(s): G.C. Temes and I.A. Young
- Source: Electronics Letters, Volume 14, Issue 9, p. 287 –288
- DOI: 10.1049/el:19780195
- Type: Article
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p.
287
–288
(2)
A novel switched-capacitor integrator is described which results in the mapping of the analogue frequency axis directly on the unit circle of the z-plane. The circuit requires one extra capacitor and additional switches. It makes the design much easier and doubles the effective sampling rate.
Realisation of three-valued c.m.o.s. cycling gates
- Author(s): J.M. Carmona ; J.L. Huertas ; J.I. Acha
- Source: Electronics Letters, Volume 14, Issue 9, p. 288 –290
- DOI: 10.1049/el:19780196
- Type: Article
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p.
288
–290
(3)
A new design technique for three-valued cycling operators is presented. The new circuits are shown to be simpler than those previously reported.
Partial fraction expansion of transfer functions with multiple quadratic poles
- Author(s): P.R. Adby
- Source: Electronics Letters, Volume 14, Issue 9, p. 290 –291
- DOI: 10.1049/el:19780197
- Type: Article
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p.
290
–291
(2)
The partial fraction expansion method presented is short and straightforward, and the matrix formulation is easily programmed for computation. The method is applicable without restriction to rational functions with multiple real or quadratic poles.
Semisymbolic analysis of network sensitivity
- Author(s): A.F. Schwarz
- Source: Electronics Letters, Volume 14, Issue 9, p. 291 –292
- DOI: 10.1049/el:19780198
- Type: Article
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p.
291
–292
(2)
Large-change and differential network sensitivity with respect to a network parameter x are expressed in terms of poles and zeros of a network function at x = x (nominal) and at either x = 0 or x = ∞. The symbolic expressions thus obtained enable one to study frequency and time-domain characteristics of network sensitivities.
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