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1993 IEEE South African Symposium on Communications and Signal Processing最新文献

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Neighbourhood Kalman filtering on scanning radars with poor resolution 低分辨率扫描雷达邻域卡尔曼滤波
1993 IEEE South African Symposium on Communications and Signal Processing Pub Date : 1993-08-06 DOI: 10.1109/COMSIG.1993.365843
I. Guest
{"title":"Neighbourhood Kalman filtering on scanning radars with poor resolution","authors":"I. Guest","doi":"10.1109/COMSIG.1993.365843","DOIUrl":"https://doi.org/10.1109/COMSIG.1993.365843","url":null,"abstract":"A method of implementing a real time neighbourhood Kalman filter on a scanning radar is presented. This method assumes that the bearing measurement is inaccurate, the detections are not always present, and no Doppler processing is done. This indicates the system applicability to existing radar systems that have rudimentary performance. The system also provides predictions that allow other real time systems to operate on the data.<<ETX>>","PeriodicalId":398160,"journal":{"name":"1993 IEEE South African Symposium on Communications and Signal Processing","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123853149","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: 0
Likelihood distributions for radio wave tomography 无线电波断层扫描的似然分布
1993 IEEE South African Symposium on Communications and Signal Processing Pub Date : 1993-08-06 DOI: 10.1109/COMSIG.1993.365877
N. Pendock
{"title":"Likelihood distributions for radio wave tomography","authors":"N. Pendock","doi":"10.1109/COMSIG.1993.365877","DOIUrl":"https://doi.org/10.1109/COMSIG.1993.365877","url":null,"abstract":"Radio wave tomography is a remote sensing technique for imaging a block of rock between two or more boreholes using radio waves. The visualization of the attenuation or slowness [inverse velocity] properties of the rock is a signal estimation problem of estimating an image of physical parameters from one-dimensional projection data. The Bayesian paradigm consists of decomposing the posterior signal estimate into a product of prior and likelihood probability distributions. We examine the choice of likelihood distribution on the final signal reconstruction. In particular, Gaussian and exponential likelihood distributions are investigated and their performance is compared for reconstructing an image of rock attenuation from a radio tomography survey conducted in a base metal mine in the northern Cape.<<ETX>>","PeriodicalId":398160,"journal":{"name":"1993 IEEE South African Symposium on Communications and Signal Processing","volume":"168 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131460812","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: 0
Automatic recognition of magnetic cheque characters with hidden Markov models 基于隐马尔可夫模型的磁性支票字符自动识别
1993 IEEE South African Symposium on Communications and Signal Processing Pub Date : 1993-08-06 DOI: 10.1109/COMSIG.1993.365866
D. Strydom, J. du Preez, S. Mostert
{"title":"Automatic recognition of magnetic cheque characters with hidden Markov models","authors":"D. Strydom, J. du Preez, S. Mostert","doi":"10.1109/COMSIG.1993.365866","DOIUrl":"https://doi.org/10.1109/COMSIG.1993.365866","url":null,"abstract":"Given a signal with a distinct pattern, one can easily define a model that represents such a signal as a sequence of states each with unique features. The models are hidden Markov models (HMM) configured in the most obvious way dependent only on the segmentation technique suggested. Each segment represents a state in the HMM. Models are proposed for recognition purposes.<<ETX>>","PeriodicalId":398160,"journal":{"name":"1993 IEEE South African Symposium on Communications and Signal Processing","volume":"102 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132705753","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: 0
Public-key cryptosystems based on elliptic curves 基于椭圆曲线的公钥密码体制
1993 IEEE South African Symposium on Communications and Signal Processing Pub Date : 1993-08-06 DOI: 10.1109/COMSIG.1993.365883
J. Botes, W. Penzhorn
{"title":"Public-key cryptosystems based on elliptic curves","authors":"J. Botes, W. Penzhorn","doi":"10.1109/COMSIG.1993.365883","DOIUrl":"https://doi.org/10.1109/COMSIG.1993.365883","url":null,"abstract":"We discuss the use of elliptic curves in cryptography. Compared to the difficulty of solving the classical discrete logarithm problem, it appears that the elliptic curve analog of the discrete logarithm problem is at least as difficult to solve, especially over GF (2/sup m/). Furthermore, elliptic curve cryptosystems might prove to have a higher bit-rate operation than conventional cryptosystems.<<ETX>>","PeriodicalId":398160,"journal":{"name":"1993 IEEE South African Symposium on Communications and Signal Processing","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133689012","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: 4
Capacity evaluation of spread spectrum multiple access 扩频多址的容量评估
1993 IEEE South African Symposium on Communications and Signal Processing Pub Date : 1993-08-06 DOI: 10.1109/COMSIG.1993.365863
P. van Rooyen, H. Ferreira
{"title":"Capacity evaluation of spread spectrum multiple access","authors":"P. van Rooyen, H. Ferreira","doi":"10.1109/COMSIG.1993.365863","DOIUrl":"https://doi.org/10.1109/COMSIG.1993.365863","url":null,"abstract":"This paper investigates the capacity of spread spectrum multiple access (SSMA) in a non-cellular environment under additive white Gaussian noise (AWGN) conditions. A theoretical system model is proposed that allows one to evaluate such a system. The probability density function of the average degradation due to the interuser interference is determined by simulations and the validity of approximating the interuser interference as a Gaussian random variable is verified. The capacity of SSMA is shown to be low compared to TDMA when operated in a non-cellular environment without forward error control (FEC) coding.<<ETX>>","PeriodicalId":398160,"journal":{"name":"1993 IEEE South African Symposium on Communications and Signal Processing","volume":"81 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113939617","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
Rural communications in multi-path channels: Spread spectrum applications 多径信道中的农村通信:扩频应用
1993 IEEE South African Symposium on Communications and Signal Processing Pub Date : 1993-08-06 DOI: 10.1109/COMSIG.1993.365851
J. van de Groenendaal, R. Braun
{"title":"Rural communications in multi-path channels: Spread spectrum applications","authors":"J. van de Groenendaal, R. Braun","doi":"10.1109/COMSIG.1993.365851","DOIUrl":"https://doi.org/10.1109/COMSIG.1993.365851","url":null,"abstract":"All radio communications occur in channels that have definite multipath characteristics. Two effects that are predominant in such a model, depending on the delay relative to the bit period, are Inter Symbol Interference (ISI) and fading. In this paper ISI is investigated in greater detail and the theoretical error performance for BPSK in a multi-path channel is derived. It is also shown how spread spectrum improves the error performance of BPSK without a \"rake\" receiver in such an environment and the selection of parameters of spread spectrum to maximize error performance is briefly discussed.<<ETX>>","PeriodicalId":398160,"journal":{"name":"1993 IEEE South African Symposium on Communications and Signal Processing","volume":"112 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123588157","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: 0
Mechanical condition monitoring of impulsively loaded equipment using neutral networks 基于中性网络的脉冲负荷设备机械状态监测
1993 IEEE South African Symposium on Communications and Signal Processing Pub Date : 1993-08-06 DOI: 10.1109/COMSIG.1993.365865
T. Snyman, A. L. Nel
{"title":"Mechanical condition monitoring of impulsively loaded equipment using neutral networks","authors":"T. Snyman, A. L. Nel","doi":"10.1109/COMSIG.1993.365865","DOIUrl":"https://doi.org/10.1109/COMSIG.1993.365865","url":null,"abstract":"The monitoring of the mechanical condition of electro-mechanical circuit breakers as reported by Demjanenko et. al. (see IEE Trans. on Power Delivery, vol. PD-7, no. 2, 1992), Park et. al. (1990), and Lai et. al. (1988) reflects the necessity of a noninvasive method for predictive maintenance. By far the most common source of malfunction of large circuit breakers is due to mechanical faults that are dependant on the number of operations of the breaker. In attempting to provide an alternative method for predicting the condition of a circuit breaker we have postulated that instead of using the spectral information we would prefer to simply make use of the original time domain signal. For the specific pattern recognition process a backpropagation trained perceptron type neural network was proposed. A variety of time domain preprocessing was applied to the signal to investigate the effect on classification. In conclusion it appears that a very accurate classification of the vibration signature of an impulsively loaded mechanical component can be achieved using a very simple neural network classifier after the application of appropriate preprocessing.<<ETX>>","PeriodicalId":398160,"journal":{"name":"1993 IEEE South African Symposium on Communications and Signal Processing","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116504170","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: 4
Hermite wavelets for multicarrier data transmission 多载波数据传输中的埃尔米特小波
1993 IEEE South African Symposium on Communications and Signal Processing Pub Date : 1993-08-06 DOI: 10.1109/COMSIG.1993.365876
M.R. Walton, H. Hanrahan
{"title":"Hermite wavelets for multicarrier data transmission","authors":"M.R. Walton, H. Hanrahan","doi":"10.1109/COMSIG.1993.365876","DOIUrl":"https://doi.org/10.1109/COMSIG.1993.365876","url":null,"abstract":"The performance of Hermite wavelets as carriers in a digital subscriber loop (DSL) system is evaluated by means of a computer simulation model. The transmission medium, various types of interference and a nearly complete implementation of the transmitter and receiver functions are modelled and simulated. Within this simulation framework, a direct comparison is possible between Hermite wavelet multicarrier modulation (MCM) and sinusoidal MCM, allowing a realistic assessment of the advantages and disadvantages of each method.<<ETX>>","PeriodicalId":398160,"journal":{"name":"1993 IEEE South African Symposium on Communications and Signal Processing","volume":"92 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126630091","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: 12
A comparison between hidden Markov models and vector quantization for speech independent speaker recognition 隐马尔可夫模型与矢量量化在语音独立说话人识别中的比较
1993 IEEE South African Symposium on Communications and Signal Processing Pub Date : 1993-08-06 DOI: 10.1109/COMSIG.1993.365856
D. Weber, J. du Preez
{"title":"A comparison between hidden Markov models and vector quantization for speech independent speaker recognition","authors":"D. Weber, J. du Preez","doi":"10.1109/COMSIG.1993.365856","DOIUrl":"https://doi.org/10.1109/COMSIG.1993.365856","url":null,"abstract":"We compare Vector Quantization and Hidden Markov Models for speaker recognition for real time recognition. A scheme to reject speakers not known to the system is described and tested. Results show that the HMM algorithm outperforms the VQ algorithm. Using a 64 state HMM, a speaker recognition accuracy of 96.1% was achieved. The rejection option generated 25.7% false rejections for a 95% confidence of a correct decision. VQ best results were 93.1% with a 61% false rejection rate for codebooks of size 128.<<ETX>>","PeriodicalId":398160,"journal":{"name":"1993 IEEE South African Symposium on Communications and Signal Processing","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126383583","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: 11
A carrier recovery scheme for 4-CPFSK with h=1/4 h=1/4的4-CPFSK载波回收方案
1993 IEEE South African Symposium on Communications and Signal Processing Pub Date : 1993-08-06 DOI: 10.1109/COMSIG.1993.365861
J. A. Schoonees, R. Braun
{"title":"A carrier recovery scheme for 4-CPFSK with h=1/4","authors":"J. A. Schoonees, R. Braun","doi":"10.1109/COMSIG.1993.365861","DOIUrl":"https://doi.org/10.1109/COMSIG.1993.365861","url":null,"abstract":"A carrier recovery scheme for 4-level CPFSK with h=1/4 is proposed. It is based on four frequency-switched Costas or in phase-quadrature (I-Q) loops, each synchronized on one of the signalling frequencies. The term \"frequency-switched\" refers to the way which one loop at a time is closed, depending on the data (frequency) estimate after decoding. From the I-Q loop's viewpoint, the CPFSK signal contains the correct signaling frequency on average only a quarter of the time. For the rest of the time, the signal is tracked by the other loops. This is not to be confused with data-aided or decision-feedback synchronization. Each loop resembles the conventional QPSK Costas loop synchronizer, with additional circuitry to rotate the signal space. Simulation results are presented.<<ETX>>","PeriodicalId":398160,"journal":{"name":"1993 IEEE South African Symposium on Communications and Signal Processing","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124445517","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
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