{"title":"Meteor-burst communications: the state of the science","authors":"S. Melville, D. Fraser","doi":"10.1109/COMSIG.1992.274279","DOIUrl":"https://doi.org/10.1109/COMSIG.1992.274279","url":null,"abstract":"MBC systems have included point-to-point links, and both fixed station and dynamic vehicular networks. Available systems range from low data rate telemetry, through medium data rate message handling to high-speed conversational voice developments. This paper outlines previous work in the field and describes current systems and technology under development. Future research and development avenues are indicated with particular reference to local contributions.<<ETX>>","PeriodicalId":342857,"journal":{"name":"Proceedings of the 1992 South African Symposium on Communications and Signal Processing","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129870446","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}
{"title":"The synthesis of a new DC-free code with asymmetrical runlength constraints developed with the ACH-algorithm","authors":"C. Menyennett, H. Ferreira","doi":"10.1109/COMSIG.1992.274309","DOIUrl":"https://doi.org/10.1109/COMSIG.1992.274309","url":null,"abstract":"Write-once recording of optical discs is an example of a channel requiring such constraints. The code was developed with the well-known Adler-Coppersmith-Hassner algorithm. Its detailed synthesis is presented, together with its error behaviour and power spectral density.<<ETX>>","PeriodicalId":342857,"journal":{"name":"Proceedings of the 1992 South African Symposium on Communications and Signal Processing","volume":"103 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133810802","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}
{"title":"The use of secret-key techniques in forward information verification","authors":"G. Kuhn","doi":"10.1109/COMSIG.1992.274292","DOIUrl":"https://doi.org/10.1109/COMSIG.1992.274292","url":null,"abstract":"The theory of secret-key authentication techniques for verification of information is discussed, using authentication in pre-paid energy systems as an example. Since in a pre-paid system there is no reverse channel to the transmitter, the data must be checked by an appended authenticity code. Several types of cryptographic attacks are possible in general authentication systems. In the pre-paid energy system the user has additionally the means to carry out a chosen-plaintext attack. The theoretical basis for the design of the authentication code is investigated.<<ETX>>","PeriodicalId":342857,"journal":{"name":"Proceedings of the 1992 South African Symposium on Communications and Signal Processing","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122174498","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}
{"title":"Maximum entropy conductivity estimation from airborne electromagnetic step-response data","authors":"N. Pendock","doi":"10.1109/COMSIG.1992.274295","DOIUrl":"https://doi.org/10.1109/COMSIG.1992.274295","url":null,"abstract":"The airborne electromagnetic method is a geophysical remote sensing technique for mapping the electrical conductivity of the earth. Many possible conductivity distributions may be constructed to explain the data. From these distributions, the one with maximum entropy is chosen since it has minimum structure not accounted for by the data and may thus be regarded as the most honest possible.<<ETX>>","PeriodicalId":342857,"journal":{"name":"Proceedings of the 1992 South African Symposium on Communications and Signal Processing","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127686395","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}
{"title":"Some unique properties and applications of perfect squares minimum phase CAZAC sequences","authors":"U.H. Rohrs, L. Linde","doi":"10.1109/COMSIG.1992.274294","DOIUrl":"https://doi.org/10.1109/COMSIG.1992.274294","url":null,"abstract":"Properties described include the Constant Amplitude (CA) and Zero AutoCorrelation (ZAC) features, the ideal unfiltered and filtered Fourier transforms, the complex time domain, phase trajectory and perfect (unfiltered as well as filtered) periodic autocorrelation function properties. Additional characteristics presented are the remarkable resemblance between the CAZAC sequences and CWFM chirp signals, as well as the relationship between their instantaneous frequency and Fourier transform representations. Examples of the generation of typical PS-MP CAZAC sequences are given. It is demonstrated that these sequences are periodically, self-invertible and therefore constitute the optimum sequences for maximum-likelihood channel estimation. The paper includes simulation results with reference to potential applications.<<ETX>>","PeriodicalId":342857,"journal":{"name":"Proceedings of the 1992 South African Symposium on Communications and Signal Processing","volume":"132 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115402737","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}
{"title":"A parallel algorithm for high-speed data compression","authors":"W. Penzhorn","doi":"10.1109/COMSIG.1992.274290","DOIUrl":"https://doi.org/10.1109/COMSIG.1992.274290","url":null,"abstract":"The Lempel-Ziv algorithm is a very efficient universal data compression technique, based upon an incremental parsing technique which maintains codebooks of parsed phrases at the transmitter and at the receiver. In an attempt to increase speed the algorithm has been parallelised to run on two processors. This requires the maintaining of two independent sets of codebooks. The algorithm was applied to the compression of various text files, and graphs illustrating these results are included.<<ETX>>","PeriodicalId":342857,"journal":{"name":"Proceedings of the 1992 South African Symposium on Communications and Signal Processing","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123250439","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}
{"title":"Iterative speaker adaptation for speech recognition","authors":"F.J. Scholtz, J. du Preez","doi":"10.1109/COMSIG.1992.274317","DOIUrl":"https://doi.org/10.1109/COMSIG.1992.274317","url":null,"abstract":"A speaker-independent speech recognition system is desirable in many applications where speaker-specific data does not exist. It speaker-independent data is available, the system could be adapted to the specific speaker, thereby reducing the recognition error rate. A new, unsupervised speaker adaptation scheme which requires no prior training phase is proposed. The algorithm improves the recognition rate as more speech data becomes available, making it most suitable for real-time implementation. In the tests conducted this algorithm yields an improvement of almost 50% on the recognition error rate.<<ETX>>","PeriodicalId":342857,"journal":{"name":"Proceedings of the 1992 South African Symposium on Communications and Signal Processing","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128431158","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}
{"title":"Early fast Doppler as a meteor-burst communications amplitude predictor","authors":"D. Fraser, A. Broadhurst","doi":"10.1109/COMSIG.1992.274284","DOIUrl":"https://doi.org/10.1109/COMSIG.1992.274284","url":null,"abstract":"EFD theory, predictions and measurements are presented. Statistical analysis of the results show correlations between EFD and trial characteristics which make forward predictions possible in an open-loop system. Estimates of improved data throughput are given. A method of implementation is given which uses an artificial neural network for trial classification and prediction.<<ETX>>","PeriodicalId":342857,"journal":{"name":"Proceedings of the 1992 South African Symposium on Communications and Signal Processing","volume":"102 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121381806","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}
{"title":"New bounds on the cardinality of double synchronization-error-correcting codes","authors":"A. Helberg, H. Ferreira","doi":"10.1109/COMSIG.1992.274293","DOIUrl":"https://doi.org/10.1109/COMSIG.1992.274293","url":null,"abstract":"This paper presents improved upper and lower bounds on the cardinality of binary codes capable of correcting one or two random synchronization errors per codeword. These bounds were derived by determining and considering the Hamming distance properties of the double synchronization-error-correcting codes. These new bounds are compared with known bounds for such codes.<<ETX>>","PeriodicalId":342857,"journal":{"name":"Proceedings of the 1992 South African Symposium on Communications and Signal Processing","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125450685","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}
{"title":"Neural networks for extracting features of objects in images as a pre-processing stage to pattern classification","authors":"F. Hoare, G. de Jager","doi":"10.1109/COMSIG.1992.274277","DOIUrl":"https://doi.org/10.1109/COMSIG.1992.274277","url":null,"abstract":"The use of neural networks to implement the extraction of features of different objects in an image is investigated. In particular the self-organising map type of neural network is described and it is shown how this can be used for feature extraction.<<ETX>>","PeriodicalId":342857,"journal":{"name":"Proceedings of the 1992 South African Symposium on Communications and Signal Processing","volume":"146 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126603163","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}