An investigation has been carried out to determine the effect of lightning on the performance of pulse code modulation (PCM) telecommunication systems. The present protection used on PCM systems is described and the e...
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An investigation has been carried out to determine the effect of lightning on the performance of pulse code modulation (PCM) telecommunication systems. The present protection used on PCM systems is described and the effects of surge conditions on system performance are identified.
Protein-calorie malnutrition (PCM) was induced by feeding male F344 rats on a 5% casein diet for 7 weeks. At appropriate times, rats from control (20% casein diet) and PCM groups were killed and alveolar macrophages (...
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Protein-calorie malnutrition (PCM) was induced by feeding male F344 rats on a 5% casein diet for 7 weeks. At appropriate times, rats from control (20% casein diet) and PCM groups were killed and alveolar macrophages (AM) were obtained by bronchoalveolar lavage. The functional integrity of the AM was determined by measuring their ability to become tumoricidal on treatment with macrophage activators, such as muramyl dipeptide (MDP) or multilamellar liposomes containing MDP or its lipophilic analog, MTP-PE. After 5 and 7 weeks, the numbers of lavaged AM per gram body weight of rats were much higher in the PCM group than in the control group. In week 3, AM from the PCM group showed spontaneous tumoricidal activity against syngeneic tumor cells, but in weeks 5 and 7 they did not. However, AM from PCM rats behaved the same way as controls in their response to activation stimuli in vitro with multilamellar liposomes containing synthetic MDP or MTP-PE. These data show that PCM affects the number of AM, but that AM from rats in a state of PCM become tumoricidal in response to activation stimuli in vitro.
A unique transmission method is proposed which utilises the advantages of alphabetic line codes with differential modulation. The method incorporates relative bipulse signalling (RBS) to transmit over optical fibres t...
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A unique transmission method is proposed which utilises the advantages of alphabetic line codes with differential modulation. The method incorporates relative bipulse signalling (RBS) to transmit over optical fibres the symbols of 3B2T ternary alphabetic line code. Together with relative monopulse signalling, the 3B2T code may prove to be an optimum solution for a universal line code in digital communication systems.
CCITT has standardized an ADPCM coding scheme at 32 kbit/s which employs a quantiser with two speeds of adaptation and an adaptive predictor with six zero and two poles. The letter investigates the benefits brought by...
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CCITT has standardized an ADPCM coding scheme at 32 kbit/s which employs a quantiser with two speeds of adaptation and an adaptive predictor with six zero and two poles. The letter investigates the benefits brought by the quantiser and the predictor, independently, when coding speech signals. The results are given in terms of the mean segmental signal/noise ratio, obtained in communication channels with bit error rates equal to 0, 10** minus **4, 10** minus **3, 10** minus **2 and 10** minus **1.
The authors describe a 32-kb/s ADPCM codec which provides high-quality speech coding and data transmission capability up to 9600 b/s. The switching algorithm is based on the detection of a modem training signal and is...
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The authors describe a 32-kb/s ADPCM codec which provides high-quality speech coding and data transmission capability up to 9600 b/s. The switching algorithm is based on the detection of a modem training signal and is found to be highly reliable in practical environments. This algorithm is thus compatible with the standard CCITT algorithm for speech and data transmission up to 4800 b/s and at the same time is transparent to data transmission at 9600 b/s.
The effects of uniformly distributed random noise on pulse-code-modulation (PCM) system signals and possible solutions are discussed. A modeling and simulation technique are utilized. It is shown that this type of noi...
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The effects of uniformly distributed random noise on pulse-code-modulation (PCM) system signals and possible solutions are discussed. A modeling and simulation technique are utilized. It is shown that this type of noise can affect the PCM system signals. These effects can be reduced, and totally eliminated.
An ADPCM transcoding system using the mathematical microprocessor TMS 32010 and based on a CCITT derived algorithm which better fits the processor facilities without incurring performance loss is described. The algori...
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ISBN:
(纸本)0444879110
An ADPCM transcoding system using the mathematical microprocessor TMS 32010 and based on a CCITT derived algorithm which better fits the processor facilities without incurring performance loss is described. The algorithm program operates a couple of channels within 125 nsec of sampling period either in transmission side (ADPCM encoding) or in receiving side (ADPCM decoding) with the same resident code. This result is achieved by the execution speed of the processor, 200 nsec/instruction, most of instructions being one cycle long, and by proper modifications of original CCITT ADPCM algorithm in order to match the device multiplier and accumulator features. The internal data memory is large enough for the storage of two channels state variables sets, arithmetic constants and intermediate results.
A 32-kbit/s, adaptive delta pulse-code-modulation (ADPCM) codec single-chip LSI, in accord with CCITT Recommendation G. 721, has been developed. Previously, hardware units realized with programmed signal processors ha...
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A 32-kbit/s, adaptive delta pulse-code-modulation (ADPCM) codec single-chip LSI, in accord with CCITT Recommendation G. 721, has been developed. Previously, hardware units realized with programmed signal processors have only been able to function as either an encoder or a decoder. Thus, two chips had been required to function as an encoder/decoder system for one channel. The developed single-chip LSI is realized with wired logics and can be used as a one-channel codec. Both an internal clock signal and an external clock signal are available for ADPCM signals. The output ports for ADPCM signals have an open-drain configuration to multiplex the output signals. Several techniques are used to reduce the chip size to 7. 12 mm x 8. 07 mm. The circuit consists of 33,000 transistors. Power consumption is typically 40 mW.
The authors describe the performance evaluation of an advanced 32-kb/s ADPCM hardware codec for speech and high-speed voiceband data, at 4. 8, 7. 2 and 9. 6 kb/s. These correspond to CCITT Recommendations V. 27 and V....
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The authors describe the performance evaluation of an advanced 32-kb/s ADPCM hardware codec for speech and high-speed voiceband data, at 4. 8, 7. 2 and 9. 6 kb/s. These correspond to CCITT Recommendations V. 27 and V. 29. The results indicate that the codec provides a subjective speech quality equivalent to that of the G. 721 ADPCM codec recommended by the CCITT, and is able to maintain the transparency of the high-speed voiceband data at 7. 2-kb/s over at least four and at 9. 6 kb/s over at least two asynchronouss tandem links, respectively. The advanced codec can quickly recover a complete synchronous operation in the tandem connections, if burst errors or short hits damage the digital links.
The effects of Gaussian noise on pulse code modulation (PCM) system signals and possible solutions are discussed. The research project uses a modeling and simulation technique. It is found that this type of noise can ...
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ISBN:
(纸本)087664972X
The effects of Gaussian noise on pulse code modulation (PCM) system signals and possible solutions are discussed. The research project uses a modeling and simulation technique. It is found that this type of noise can affect the PCM system signals. These effects can be reduced, even totally eliminated.
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