1,721,275 research outputs found
Progressive coding of error diffused images
No full textIEEE International Conference on Image Processing, Vol. III, pp. 969-972, Rochester, N.Y
HIGH TEMPERATURE FORMING OF TI-6AL-4V ALLOY CONSIDERING MICROSTRUCTURAL EVOLUTION
No full text11scopu
Blind-Equalised and Turbo Coded Satellite Based Digital Video Broadcasting
No full textThe Pan-European Digital Satellite Video Broadcasting (DVB-S) system's performance is characterised. Various configurations of blind equalisers and convolutional codecs operating at different code rates were investigated. The standard system's performance was improved upon replacing the conventional convolutional codec by a turbo codec. Lastly, the feasibility of employing 16-level Quadrature Amplitude Modulation (16-QAM) within the DVB-S system is demonstrated, potentially doubling the available bitrate hence improving the associated video quality at the cost of a higher Signal-to-Noise Ratio (SNR) requirement. This extra transmitted power requirement can be eliminated upon invoking a similar complexity turbo codec, which requires lower transmitted power for attaining the same performance as the standard convolutional codes
OFDM-Based Turbo-Coded Hierarchical and Non-Hierarchical Terrestrial Mobile Digital Video Broadcasting
Full text linkThe feasibility of terrestrial Digital Video Broadcast (DVB) to mobile receivers is studied and turbo coded performance enhancements are proposed. Initially, the MPEG-2 codec is subjected to a rigorous bit error sensitivity investigation, in order to assist in designing various error protection schemes for wireless DVB transmission. The turbo codec is shown to provide Signal-to-Noise Ratio (SNR) performance advantages in excess of 5–6 dB over conventional convolutional coding both in terms of bit error rate and video quality. Our experiments suggested that—despite our expectations—multi-class data partitioning did not result in error resilience improvements, since a high proportion of relatively sensitive video bits had to be relegated to the lower integrity subchannel, when invoking a powerful low-rate channel codec in the high-integrity protection class. Nonetheless, DVB transmission to mobile receivers is feasible, when using turbo-coded OFDM transceivers at realistic power-budget requirements under the investigated highly dispersive fading channel conditions. It is interesting to note furthermore that the 5–6 dB SNR improvement due to turbo coding allows us to invoke for example the double-throughput 16-level Quadrature Amplitude Modulation (16-QAM) mode instead of the standard convolutional-coded 4-QAM mode. This facilitates doubling the bit rate and hence improving the video quality. Index Terms—DVB, DVB-T, error sensitivity, hierarchical video transmission, mobile video broadcast, MPEG-2, OFDM, QAM, terrestrial video broadcast, wireless video broadcast
Effect of concurrent accumulative roll bonding (ARB) process and various heat treatment on the microstructure, texture and mechanical properties of AA1050 sheets
No full text© 2022 The AuthorsThis study investigated the microstructure, texture, and mechanical properties of 1050 aluminum alloy sheets that underwent the accumulative roll bonding (ARB) method. The ARB proceeded up to eight passes in three ways: conventional process, preheat between rolling passes (preheating) or anneal between rolling passes (annealing). Heat treatment was done between the ARB passes for 5 min at 150 °C. The mean grain width of the 1050 Al sheet that was 11 μm before ARB, decreased to 295.73 nm, 317.33 nm, or 339.23 nm after six ARB passes in the conventional process, annealed or preheated conditions, respectively. Concurrent heat treatments cause a decrease in the strength of the texture components of Al sheets that were elaborated by the ARB method. Even though conventional and annealed processes successfully enhanced the microhardness by ∼80% and tripled the tensile strength, these improvements were weaker in the preheated condition than the other conditions due to dynamic recovery.11Nsciescopu
Satellite Based Turbo-Coded, Blind-Equalised 4-QAM and 16-QAM Digital Video Broadcasting
No full textThe Pan-European Digital Satellite Video Broadcasting (DVB-S) system’s performance is characterized and improved with the aid of turbo coding and multi-level modulation. Specifically, various configurations of blind equalizers and convolutional as well as turbo codecs operating at different code rates were investigated. The standard system’s performance was improved upon replacing the conventional convolutional codec by a turbo codec. Lastly, the feasibility of employing blind equalized 16-level modulation within the DVB-S system is demonstrated, potentially doubling the available bitrate and hence improving the associated video quality at the cost of a higher Signal-to-Noise Ratio (SNR) requirement. This extra transmitted power requirement can be eliminated upon invoking the more complex turbo codec, which requires lower transmitted power for attaining the same performance as the standard convolutional codes. Index Terms—Blind equalization, digital video broadcasting, DVB, DVB-S, QAM, quadrature amplitude modulation
Turbo-Coded Digital Video Broadcasting for Mobile Environments
No full textThe system performance of a range of turbo coded digital video broadcasting (DVB) schemes is studied using a variety of orthogonal frequency division multiplex (OFDM) modem modes in both stationary and mobile environments. The turbo codec is shown to provide substantial performance advantage over conventional convolutional coding both in bit error rate and video quality terms
Turbo-Coded Terrestrial Mobile Video Broadcasting
No full textIn this contribution we investigated the performance of turbo-coded MPEG-2 compression based terrestrial mobile video broadcasting. Our experiments suggested that non-hierarchical, ie single-class protection of the MPEG-2 video stream exhibited a similar error resilience to twin-class data partitioning, since a high proportion of relatively sensitive video bits had to be relegated to the lower integrity subchannel, when invoking a powerful low-rate channel codec in the high-integrity protection class for the sake of ensuring the error-free reception of the more sensitive MPEG-2 video bits, such as control headers, etc
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