The authors propose a improved variable-bit-rate modulo-PCM (VBR-MPCM). It has the same performance as conventional VBR-MPCM, but it has lower complexity and shorter time delay. The authors also propose variable-bit-r...
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The authors propose a improved variable-bit-rate modulo-PCM (VBR-MPCM). It has the same performance as conventional VBR-MPCM, but it has lower complexity and shorter time delay. The authors also propose variable-bit-rate modulo-PCM using adaptive predictor (VBR-MPCM-AP) which differs in that it has an adaptive rather than fixed predictor. Its performance is about 0[dB]about3[dB] better than that of improved VBR-MPCM.
Different coding algorithms have been proposed for a 34 Mbit/s transmission of a digital colour TV signal. Most of them use sampling frequencies of 10.125 MHz for the luminance signal and 3.375 MHz for the chrominance...
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Differential PCM (DPCM) has often been used for encoding of images, but its efficiency is very poor at low transmission rates. Discussion of DPCM is based on an autoregressive (AR) model which is causal in the case of...
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Differential PCM (DPCM) has often been used for encoding of images, but its efficiency is very poor at low transmission rates. Discussion of DPCM is based on an autoregressive (AR) model which is causal in the case of raster scan sampling. This paper proposes a two-dimensional interpolative DPCM which is based on such a model. This method has the following special feature: if the output samples of a DPCM process based on a causal AR model are regarded as intermediate decoded values, then the final decoded values are yielded by a filtering process based on an interpolative model. The results of simulation using actual images demonstrate SN ratio improvement at a low bit rate (1 bit/pel) and also the stability of encoding characteristics in the case of quantitative step-size variations. It is shown that fixing of the prediction and interpolation coefficients result only in slight deterioration.
Characteristic features of pulse code modulation due to coding methods have been investigated, and a modulator with counting coder and a demodulator with feedback decoder were developed fluidically. A 3 bit equipment ...
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ISBN:
(纸本)0080316816
Characteristic features of pulse code modulation due to coding methods have been investigated, and a modulator with counting coder and a demodulator with feedback decoder were developed fluidically. A 3 bit equipment by commercially available devices proved that coding and decoding could be realized approximately less than 10 Hz of pneumatic signal. Characteristics of interpolation filter exert a considerable influence upon demodulation processes.
Describes a solid-state subscriber line interface circuit (SLIC) designed by SGS-Thompson Microelectronics to eliminate the high amplitude transients caused by relay contact bounce. This SLIC developed for analogue ca...
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Describes a solid-state subscriber line interface circuit (SLIC) designed by SGS-Thompson Microelectronics to eliminate the high amplitude transients caused by relay contact bounce. This SLIC developed for analogue cards consists of two devices: the L3000, realised in HV technology that interfaces directly to the line; and the L3090, which integrates all of the control and system interface functions. In the PABX sector, a frequently requested function is the conference call. This function is possible with a single chip due to VLSI technology. The integrated digital PCM processor developed by SGS-Thompson can receive up to 32 channels from the TDM input highway and accepts all the basic rates: 1536, 1544, and 2048 kbit/s.< >
The authors give the background and a system description of the UXDS digital telephone exchange, and consider direct connection to 30-channel PCM. They also discuss aspects of the services and supports needed for rura...
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The authors give the background and a system description of the UXDS digital telephone exchange, and consider direct connection to 30-channel PCM. They also discuss aspects of the services and supports needed for rural telecommunications projects.< >
The authors describe a fully digitised TDMA system, with 64 kbits/s PCM for voice coding/decoding, that can be directly interfaced to a digital exchange. The direct digital interface is described, and the processing a...
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The authors describe a fully digitised TDMA system, with 64 kbits/s PCM for voice coding/decoding, that can be directly interfaced to a digital exchange. The direct digital interface is described, and the processing and format of the digital signal for the interface discussed. The design of a large capacity PCM-TDMA subscriber radio system is considered.< >
A differential pulse code modulation (DPCM) coding technique called 'block' DPCM is proposed. It attempts to achieve a bit rate below 2. 0 bits/pixel without using adaptive methods. Two slightly different sche...
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ISBN:
(纸本)0892527420
A differential pulse code modulation (DPCM) coding technique called 'block' DPCM is proposed. It attempts to achieve a bit rate below 2. 0 bits/pixel without using adaptive methods. Two slightly different schemes called 'maximum' block DPCM and 'sequential' block DPCM are introduced. Linear interpolation is used to fill in untransmitted samples. Filtering is applied in order to improve image quality. The performance of these two schemes are evaluated by simulation.
Die Berechnungsverfahren für den Signalgeräuschabstand nach der CCITT-Empfehlung 0.133 und 0.132 werden im Zeit-, Frequenz- und Wahrscheinlichkeitsbereich aufgeführt. Für die gleichmäßige...
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Two approaches are presented for accommodating 9. 6-kb/s modem signals (e. g. , V. 29) through 32-kb/s ADPCM (adaptive differential pulse-codemodulation) links: (1) small changes in the existing algorithm and (2) cod...
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Two approaches are presented for accommodating 9. 6-kb/s modem signals (e. g. , V. 29) through 32-kb/s ADPCM (adaptive differential pulse-codemodulation) links: (1) small changes in the existing algorithm and (2) coding with ADPCM incorporating a 5-bit, rather than 4-bit, quantizer. For each approach, tradeoffs between performance and implementation complexity are described. It is shown that by changing a few parameters of the standard ADPCM algorithm, acceptable performance (i. e. block error rate less than equivalent to 10**-**2) can be obtained in the presence of analog impairments after one ADPCM coding. By using a 5-bit quantizer at a sampling rate of 6. 4 kHz, acceptable performance with two ADPCM codings is found only in the presence of mild envelope delay distortion. It is felt that if acceptable performance under conditions of multiple ADPCM codings and analog impairments is required, a 40-kb/s rate must be used.
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