In the step by step change from analog communication networks to digital networks the problems of the accumulation of noise portions are studied. A particular attention is paid in this case to the quantization noise. ...
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In the step by step change from analog communication networks to digital networks the problems of the accumulation of noise portions are studied. A particular attention is paid in this case to the quantization noise. As the theoretical determination of the noise accumulation is not possible. The method of computer simulation is used for this problem. Particular attention is given to the selection of numerical values for period lengths as well as to the reduction of the numerical requirements.
The realization is described of a regenerator with the fundamental functions equalization and amplification, timing recovery, amplitude and time division as well as restoration of the prescribed form of transmitting p...
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The realization is described of a regenerator with the fundamental functions equalization and amplification, timing recovery, amplitude and time division as well as restoration of the prescribed form of transmitting pulses. The optimization of the equalizer eigenvalues with a special derivation-free gradient procedure is considered. The results obtained in Part 1 are verified for a real equalizer.
The digital communication technology embraces the digitization of analog signals, multiplexing of digital signals with stardardized bit rates and transmission of these signals over radio and telephone. The pulsecode ...
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The digital communication technology embraces the digitization of analog signals, multiplexing of digital signals with stardardized bit rates and transmission of these signals over radio and telephone. The pulse code modulation equipment is presented that is used in digitization and multiplexing of telephone signals in public telephone networks. The necessary logic and control functions are considered and the large scale integrated circuits building blocks emphasized.
Nonadaptive predictors for intra-frame differential PCM (DPCM) coding of TV signals exhibit large prediction errors at contours and edges in pictures. Therefore, they do not lend themselves to be used for high detaile...
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Nonadaptive predictors for intra-frame differential PCM (DPCM) coding of TV signals exhibit large prediction errors at contours and edges in pictures. Therefore, they do not lend themselves to be used for high detailed pictures with many contours. On the basis of the contour prediction a new adaptive predictor is proposed, whereby flat areas and contours of a picture are processed with different predictors. Only previously transmitted picture elements are used for the adaptive prediction algorithm, so no additional switching information has to be transmitted. The gain of the new predictor is compared with known nonadaptive and adaptive predictors by means of computer simulations. The comparisons are based on quantitative criteria as well as subjective tests. An advantage of the presented prediction algorithm is the considerable reduction of the frequency of large prediction errors in pictures. Compared to other prediction algorithms, this allows a reduction of the transmission rate.
A scheme is described for a logarithmic pulse-amplitude to code converter with a dynamic range of 50 dB. The sensitivity of the converter is 250 uv and its conversion frequency is 1 MHz. The temperature instability of...
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A scheme is described for a logarithmic pulse-amplitude to code converter with a dynamic range of 50 dB. The sensitivity of the converter is 250 uv and its conversion frequency is 1 MHz. The temperature instability of the threshold is less than equivalent to 0. 1% over the temperature range plus 15 to plus 50 degree C. The differential nonlinearity of the converter is 3%. A method is given for measuring the differential nonlinearity of logarithmic converters.
The codec is the main component of a PCM system which has been developed by the telephone industry to maximise the number of individual channels which can be routed through a single conductor. The codec test adaptor p...
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The codec is the main component of a PCM system which has been developed by the telephone industry to maximise the number of individual channels which can be routed through a single conductor. The codec test adaptor presented here, in combination with the general purpose LSI test system, has been successfully employed in codec characterization and production testing.
Advances in digital communications and the growing need to make efficient use ofthe existing telephone network has led many PTT administrations to install PCM equipment on routes handling heavy traffic. In line with t...
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Advances in digital communications and the growing need to make efficient use ofthe existing telephone network has led many PTT administrations to install PCM equipment on routes handling heavy traffic. In line with these developments, the use of higher order PCM is becoming wider on trucks as well as on junction networks. In conjunction with the Turkish PTT administration, a second-order PCM multiplex utilizing positive-zero-negative justification has been realized to investigate its behavior in synchronous and plesiochronous operation. The system and some preliminary results are described.
PCM equipment has been used by British and other telecommunication administrations in the 30-channel format since the early 1970's and before that in the 24-channel format. By the late 1970's it was considered...
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PCM equipment has been used by British and other telecommunication administrations in the 30-channel format since the early 1970's and before that in the 24-channel format. By the late 1970's it was considered necessary to develop new equipment which would take advantage of new ideas and techniques to produce a design which was versatile, easy to manufacture, cost competitive, low in power consumption, and of minimal size. This paper describes that equipment. The development objectives have been achieved by the use of custom designed IC and a new British equipment practice Tep-1(E).
Severely malnourished children should stay in hospital for as short a time as possible to minimize the harmful effects of separation from their families and institutionalization and to ensure that scarce hospital beds...
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Severely malnourished children should stay in hospital for as short a time as possible to minimize the harmful effects of separation from their families and institutionalization and to ensure that scarce hospital beds are used efficiently. Repletion of wasting, that is, attainment of ideal or expected weight-for-height (EWH) has been recommended as the criterion for recovery from PEM. As it may be impractical to measure length, a simple visual means of monitoring the progress of children recovering from PEM is needed. A“catch up”growth chart was devised, based on the mean deficit in weight-forheight of 2–3 kg of 827 children admitted to the ward of the Tropical Metabolism Research Unit (TMRU) in 1958–1976. This deficit was restored in 10.3 (±3.95 SD) weeks by a subsample of 52 recent admissions, a rate of recovery similar to previous reports from the TMRU. In 1972/1973 a similar treatment regime using oil-fortified milk (“high energy feeding”) was instituted in 4 rural hospitals in Jamaica. As the majority (72%) of the children who were measured attained 90%of EWH, the chart proposed will be practicable in
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