Proceedings of the Nineteenth National Radio Science Conference最新文献_第2页

Performance of analysis-by-synthesis low-bit rate speech coders in mobile radio channel 基于合成分析的低比特率语音编码器在移动无线电信道中的性能

Proceedings of the Nineteenth National Radio Science Conference Pub Date : 2002-11-07 DOI: 10.1109/NRSC.2002.1022643

S.M. El Noubi, M. El-Said Nasr, E. Gemeay

{"title":"Performance of analysis-by-synthesis low-bit rate speech coders in mobile radio channel","authors":"S.M. El Noubi, M. El-Said Nasr, E. Gemeay","doi":"10.1109/NRSC.2002.1022643","DOIUrl":"https://doi.org/10.1109/NRSC.2002.1022643","url":null,"abstract":"Low bit rate coding of voice is critical for accommodating more users on channels that have inherent limitations of bandwidth or power-like cellular radio or satellite links. Analysis-by-Synthesis (AbS) coders are the candidate coders for producing good quality speech in the range from 4.8 to 16 kb/s. The multi-pulse excited linear predictive coder (MPE-LPC), and the regular-pulse excited linear predictive coder (RPE-LPC) are among very large number of (AbS) speech coders. The MPE and RPE can produce high quality speech at bit rate lower than 9.6 kb/s with a fairly moderate complexity. In this paper we introduce a novel approach for achieving variable-bit rates below 9.6 kb/s by using switched quantization. The issues of transmitting a 9.6 kb/s MPE arid RPE analysis-by-synthesis predictive coded speech over a mobile radio-fading channel are discussed. The coder robustness and the sensitivity of speech-carrying bits to channel errors are also presented. Further, the performance of a /spl pi//4 differential quadrature phase shift keying (/spl pi//4 DQPSK) method over Rayleigh fading mobile radio channel is presented by the coder output. Objective and subjective tests are used to show the effect of the Rayleigh fading mobile radio channel on the performance of the coder, and also determine the amount of the minimum value of channel signal to noise power ratio (SNR dB) required to obtain a good speech quality.","PeriodicalId":231600,"journal":{"name":"Proceedings of the Nineteenth National Radio Science Conference","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125544058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

A novel cellular structure for stratospheric platform mobile communications 一种用于平流层平台移动通信的新型蜂窝结构

Proceedings of the Nineteenth National Radio Science Conference Pub Date : 2002-11-07 DOI: 10.1109/NRSC.2002.1022642

M. Nofal, M. Hadhood, M. Dessouky, Y. Albagory

引用次数: 13

Diffusion tensor magnetic resonance imaging of lesions in multiple sclerosis patients 多发性硬化症患者病变的扩散张量磁共振成像

Proceedings of the Nineteenth National Radio Science Conference Pub Date : 2002-11-07 DOI: 10.1109/NRSC.2002.1022674

I. Elshafiey

{"title":"Diffusion tensor magnetic resonance imaging of lesions in multiple sclerosis patients","authors":"I. Elshafiey","doi":"10.1109/NRSC.2002.1022674","DOIUrl":"https://doi.org/10.1109/NRSC.2002.1022674","url":null,"abstract":"Multiple sclerosis (MS) is a disease that affects the central nervous system (CNS). Diffusion tensor magnetic resonance imaging (DT-MRI) provides an advanced tool for a quantitative noninvasive technique to detect MS lesions. This technique exploits the sensitivity of MRI to random water diffusion in tissues in the presence of diffusion gradient pulses incorporated into the imaging sequence. Large diffusion weighting is achieved by increasing the magnitude of diffusion pulses; it is essential for the generation of a high SNR diffusion signal. However, large diffusion gradients induce strong eddy currents in the metallic structure of the cryostat, resulting in distortion of MR images. This suggests that moderate diffusion weighting should be optimum for inspection. This study investigates the use of DT-MRI of the brain of human MS patients at a diffusion level of 480 s/mm/sup 2/, which proved to be optimum in a previous study conducted on normal volunteers. MRI studies were performed on a GE 1.5 tesla scanner at Hermann Hospital, Houston, using a single shot diffusion weighted echo planar imaging sequence. All acquisitions were cardiac gated to minimize the effect on the images of cerebrospinal fluid (CSF) pulsation. The presented quantitative results compare various DT-MRI stains for lesion and normal tissue and they reveal that DT-MRI is a powerful noninvasive technique for detecting MS lesions in the human brain.","PeriodicalId":231600,"journal":{"name":"Proceedings of the Nineteenth National Radio Science Conference","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116069621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

An automatic testing technique for PLDs pld的自动测试技术

Proceedings of the Nineteenth National Radio Science Conference Pub Date : 2002-11-07 DOI: 10.1109/NRSC.2002.1022649

A. Elsayed, M. Elbably, H. Elbolok

引用次数: 3

Design of metal electrodes with six important electrooptic materials 六种重要电光材料的金属电极设计

Proceedings of the Nineteenth National Radio Science Conference Pub Date : 2002-11-07 DOI: 10.1109/NRSC.2002.1022666

A. Zaghloul

引用次数: 1

MVDDS network layers adapted with DVB-RCS as a terrestrial RC solution MVDDS网络层采用DVB-RCS作为地面RC解决方案

Proceedings of the Nineteenth National Radio Science Conference Pub Date : 2002-11-07 DOI: 10.1109/NRSC.2002.1022669

M. Rizk, M. M. Ayoub

引用次数: 2

Design of ADPLL for good phase and frequency tracking performance 设计具有良好相位和频率跟踪性能的ADPLL

Proceedings of the Nineteenth National Radio Science Conference Pub Date : 2002-11-07 DOI: 10.1109/NRSC.2002.1022634

A. Khalil, K. T. Ibrahim, A. Salama

引用次数: 11

Liver tumor hyperthermia using an N/spl times/N ultrasound phased array 采用N/spl次/N超声相控阵进行肝肿瘤热疗

Proceedings of the Nineteenth National Radio Science Conference Pub Date : 2002-11-07 DOI: 10.1109/NRSC.2002.1022677

N. Ismail, K. El-ela

引用次数: 1

A new fuzzy adaptive perceptual image coding system 一种新的模糊自适应感知图像编码系统

Proceedings of the Nineteenth National Radio Science Conference Pub Date : 2002-11-07 DOI: 10.1109/NRSC.2002.1022639

S. El-Khamy, I. Ghaleb, N. El-Yamany

引用次数: 3

An RF CMOS modified-cascode LNA with inductive source degeneration 电感源退化的RF CMOS修饰级联LNA

Proceedings of the Nineteenth National Radio Science Conference Pub Date : 2002-11-07 DOI: 10.1109/NRSC.2002.1022654

Hajiz, Khaled Sharafw, E. El-Diwany, Hudia. El-Hennawyw

引用次数: 8