Pub Date : 1998-09-07DOI: 10.1109/COMSIG.1998.736980
A. Franzsen
This paper describes the basic physics of thermal remote sensing, describes some thermal remote sensing platforms and gives examples of applications for the earth sciences. Thermal remote sensing is a powerful management tool for the control of sub-surface fires and pollution plumes.
{"title":"Thermal remote sensing for earth science applications","authors":"A. Franzsen","doi":"10.1109/COMSIG.1998.736980","DOIUrl":"https://doi.org/10.1109/COMSIG.1998.736980","url":null,"abstract":"This paper describes the basic physics of thermal remote sensing, describes some thermal remote sensing platforms and gives examples of applications for the earth sciences. Thermal remote sensing is a powerful management tool for the control of sub-surface fires and pollution plumes.","PeriodicalId":294473,"journal":{"name":"Proceedings of the 1998 South African Symposium on Communications and Signal Processing-COMSIG '98 (Cat. No. 98EX214)","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125517010","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}
Pub Date : 1998-09-07DOI: 10.1109/COMSIG.1998.736930
A. Wilkinson, R. Lord, M. R. Inggs
This paper describes a processing technique for combining stepped-frequency waveforms efficiently to obtain higher range resolution. Essentially this method involves the reconstruction of a wider portion of the target's reflectivity spectrum by combining the individual spectra of the transmitted narrow-bandwidth pulses in the frequency domain. This paper describes the signal processing steps involved, and shows simulation results which validate and illustrate the method.
{"title":"Stepped-frequency processing by reconstruction of target reflectivity spectrum","authors":"A. Wilkinson, R. Lord, M. R. Inggs","doi":"10.1109/COMSIG.1998.736930","DOIUrl":"https://doi.org/10.1109/COMSIG.1998.736930","url":null,"abstract":"This paper describes a processing technique for combining stepped-frequency waveforms efficiently to obtain higher range resolution. Essentially this method involves the reconstruction of a wider portion of the target's reflectivity spectrum by combining the individual spectra of the transmitted narrow-bandwidth pulses in the frequency domain. This paper describes the signal processing steps involved, and shows simulation results which validate and illustrate the method.","PeriodicalId":294473,"journal":{"name":"Proceedings of the 1998 South African Symposium on Communications and Signal Processing-COMSIG '98 (Cat. No. 98EX214)","volume":"116 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115199878","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}
Pub Date : 1998-09-07DOI: 10.1109/COMSIG.1998.736939
V. Mpako, F. Takawira
The works that have been published on spread slotted ALOHA systems have assumed that power control errors are lognormally distributed. The analytical models that these works have produced have shown that the power control errors cause a reduction in the channel capacity (maximum throughput). On the other hand, the research done in slotted ALOHA systems has shown that differences in the received powers of packets contending for a common receiver lead to the capture effect. The capture effect is known to improve the channel capacity, packet delay and other important performance measures. This paper, motivated by these apparent uncertainties, examines the effects of power control errors in a spread-spectrum slotted ALOHA system using a single threshold in a channel-load-sensing scheme. The system assumes a finite population of data users that have variable length messages. The performance of the system with perfect and imperfect power control is examined through simulations. The capacity for systems with both perfect and imperfect power control is compared.
{"title":"Effects of power control error on the performance of spread ALOHA protocols","authors":"V. Mpako, F. Takawira","doi":"10.1109/COMSIG.1998.736939","DOIUrl":"https://doi.org/10.1109/COMSIG.1998.736939","url":null,"abstract":"The works that have been published on spread slotted ALOHA systems have assumed that power control errors are lognormally distributed. The analytical models that these works have produced have shown that the power control errors cause a reduction in the channel capacity (maximum throughput). On the other hand, the research done in slotted ALOHA systems has shown that differences in the received powers of packets contending for a common receiver lead to the capture effect. The capture effect is known to improve the channel capacity, packet delay and other important performance measures. This paper, motivated by these apparent uncertainties, examines the effects of power control errors in a spread-spectrum slotted ALOHA system using a single threshold in a channel-load-sensing scheme. The system assumes a finite population of data users that have variable length messages. The performance of the system with perfect and imperfect power control is examined through simulations. The capacity for systems with both perfect and imperfect power control is compared.","PeriodicalId":294473,"journal":{"name":"Proceedings of the 1998 South African Symposium on Communications and Signal Processing-COMSIG '98 (Cat. No. 98EX214)","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122563067","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}
Pub Date : 1998-09-07DOI: 10.1109/COMSIG.1998.736991
J.C. Kruger, P. Meyer
An experimental study of smooth finline to waveguide transitions is presented. It is shown that no optimum design exists and that very simple geometric curves can achieve better performance than some complex ones. A novel transformer-coupled coaxial-to-waveguide transition is also presented using a simple structure to achieve -20 dB of reflection across a 25% bandwidth.
{"title":"Finline and coaxial line to waveguide transitions at X-band","authors":"J.C. Kruger, P. Meyer","doi":"10.1109/COMSIG.1998.736991","DOIUrl":"https://doi.org/10.1109/COMSIG.1998.736991","url":null,"abstract":"An experimental study of smooth finline to waveguide transitions is presented. It is shown that no optimum design exists and that very simple geometric curves can achieve better performance than some complex ones. A novel transformer-coupled coaxial-to-waveguide transition is also presented using a simple structure to achieve -20 dB of reflection across a 25% bandwidth.","PeriodicalId":294473,"journal":{"name":"Proceedings of the 1998 South African Symposium on Communications and Signal Processing-COMSIG '98 (Cat. No. 98EX214)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122818753","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}
Pub Date : 1998-09-07DOI: 10.1109/COMSIG.1998.736931
S. Wuyts, M. R. Inggs
This paper presents a study of the use of PVM (parallel virtual machine) to improve the speed of synthetic aperture radar (SAR) image processing. PVM is a software system that enables a user-configurable pool of heterogeneous computers to be used as a virtual machine. The SAR processing test software performed simplified range and azimuth compression on simulated SAR images of a point target. Results show that PVM improves the time taken to process a SAR image once system factors are optimised.
{"title":"SAR processing using PVM","authors":"S. Wuyts, M. R. Inggs","doi":"10.1109/COMSIG.1998.736931","DOIUrl":"https://doi.org/10.1109/COMSIG.1998.736931","url":null,"abstract":"This paper presents a study of the use of PVM (parallel virtual machine) to improve the speed of synthetic aperture radar (SAR) image processing. PVM is a software system that enables a user-configurable pool of heterogeneous computers to be used as a virtual machine. The SAR processing test software performed simplified range and azimuth compression on simulated SAR images of a point target. Results show that PVM improves the time taken to process a SAR image once system factors are optimised.","PeriodicalId":294473,"journal":{"name":"Proceedings of the 1998 South African Symposium on Communications and Signal Processing-COMSIG '98 (Cat. No. 98EX214)","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129327300","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}
Pub Date : 1998-09-07DOI: 10.1109/COMSIG.1998.736920
C. Naidoo, P. van Rooyen
New techniques to suppress narrow-band and multiple-access interference for spread-spectrum (SS) systems are continually being researched for use in the growing cellular CDMA market. This paper investigates the feasibility of using a fuzzy logic technique to adapt the MMSE detector for the suppression of narrow-band interference (NBI). The fuzzy logic adaptation (FLA) technique is described and its performance is compared to the least-mean-square (LMS) and the recursive-least-square (RLS) adaptive algorithms. It is found that the fuzzy logic technique considered gives a performance improvement over the conventional and adaptive algorithm, while it fails to match the performance of the RLS adaptive algorithm.
{"title":"A fuzzy logic interference suppression algorithm for DS-SS communications","authors":"C. Naidoo, P. van Rooyen","doi":"10.1109/COMSIG.1998.736920","DOIUrl":"https://doi.org/10.1109/COMSIG.1998.736920","url":null,"abstract":"New techniques to suppress narrow-band and multiple-access interference for spread-spectrum (SS) systems are continually being researched for use in the growing cellular CDMA market. This paper investigates the feasibility of using a fuzzy logic technique to adapt the MMSE detector for the suppression of narrow-band interference (NBI). The fuzzy logic adaptation (FLA) technique is described and its performance is compared to the least-mean-square (LMS) and the recursive-least-square (RLS) adaptive algorithms. It is found that the fuzzy logic technique considered gives a performance improvement over the conventional and adaptive algorithm, while it fails to match the performance of the RLS adaptive algorithm.","PeriodicalId":294473,"journal":{"name":"Proceedings of the 1998 South African Symposium on Communications and Signal Processing-COMSIG '98 (Cat. No. 98EX214)","volume":"108 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124156777","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}
Pub Date : 1998-09-07DOI: 10.1109/COMSIG.1998.736952
Vladimir B. Bajic, I. Bajić
The information spectrum method (ISM) and the resonant recognition model (RRM) represent a methodology based on signal processing that analyses characteristic spectral motifs in DNA/RNA and protein sequences. Some inconsistencies have been reported recently with regard to the spectral characterization of specific biological sequences utilizing the ISM (RRM) and this motivated examination of the basics of the ISM (RRM). This note provides some discussions on the methodology on which the ISM and RRM are based and shows a potential reason why the ISM and the RRM produce inaccurate and unreliable results. Two examples are given to backup the analysis and discussion.
{"title":"Some problems in application of information spectrum method and resonant recognition model for cross-spectral analysis of DNA/RNA sequences","authors":"Vladimir B. Bajic, I. Bajić","doi":"10.1109/COMSIG.1998.736952","DOIUrl":"https://doi.org/10.1109/COMSIG.1998.736952","url":null,"abstract":"The information spectrum method (ISM) and the resonant recognition model (RRM) represent a methodology based on signal processing that analyses characteristic spectral motifs in DNA/RNA and protein sequences. Some inconsistencies have been reported recently with regard to the spectral characterization of specific biological sequences utilizing the ISM (RRM) and this motivated examination of the basics of the ISM (RRM). This note provides some discussions on the methodology on which the ISM and RRM are based and shows a potential reason why the ISM and the RRM produce inaccurate and unreliable results. Two examples are given to backup the analysis and discussion.","PeriodicalId":294473,"journal":{"name":"Proceedings of the 1998 South African Symposium on Communications and Signal Processing-COMSIG '98 (Cat. No. 98EX214)","volume":"104 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128014916","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}
Pub Date : 1998-09-07DOI: 10.1109/COMSIG.1998.736977
G.S. Doyle, M. R. Inggs
An assessment is made of SIR-C data and its usefulness in the detection and mapping of buried, abandoned meanders of the lower Orange River. Numerous image-processing techniques were tested on the data as a means of enhancing these palaeo-channels for detection. A comparison is made with Landsat TM imagery, and fusion of the two data sets is also assessed as an exploration tool. The main conclusion reached was that the penetration depth of the microwave radiation was not sufficient for the radar to be a significantly more useful tool in this particular environment; an environment where the channels have been buried to a depth greater than a few metres, and where the climate cannot be considered to be hyper-arid. The texture discrimination capabilities of the radar were more useful in this case study than any ground penetration that might have occurred.
{"title":"Dual-frequency multi-polarimetric SAR as a tool for palaeo-drainage mapping in the Northern Cape Province","authors":"G.S. Doyle, M. R. Inggs","doi":"10.1109/COMSIG.1998.736977","DOIUrl":"https://doi.org/10.1109/COMSIG.1998.736977","url":null,"abstract":"An assessment is made of SIR-C data and its usefulness in the detection and mapping of buried, abandoned meanders of the lower Orange River. Numerous image-processing techniques were tested on the data as a means of enhancing these palaeo-channels for detection. A comparison is made with Landsat TM imagery, and fusion of the two data sets is also assessed as an exploration tool. The main conclusion reached was that the penetration depth of the microwave radiation was not sufficient for the radar to be a significantly more useful tool in this particular environment; an environment where the channels have been buried to a depth greater than a few metres, and where the climate cannot be considered to be hyper-arid. The texture discrimination capabilities of the radar were more useful in this case study than any ground penetration that might have occurred.","PeriodicalId":294473,"journal":{"name":"Proceedings of the 1998 South African Symposium on Communications and Signal Processing-COMSIG '98 (Cat. No. 98EX214)","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127901544","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}
Pub Date : 1998-09-07DOI: 10.1109/COMSIG.1998.736937
J. J. Francis, G. de Jager
A method of estimating the motion of froth from watershed segmented images is presented. The method is compared to a block motion estimation method and an optical flow algorithm. The three algorithms are experimentally compared and their suitability for froth imaging is examined.
{"title":"An investigation into the suitability of various motion estimation algorithms for froth imaging","authors":"J. J. Francis, G. de Jager","doi":"10.1109/COMSIG.1998.736937","DOIUrl":"https://doi.org/10.1109/COMSIG.1998.736937","url":null,"abstract":"A method of estimating the motion of froth from watershed segmented images is presented. The method is compared to a block motion estimation method and an optical flow algorithm. The three algorithms are experimentally compared and their suitability for froth imaging is examined.","PeriodicalId":294473,"journal":{"name":"Proceedings of the 1998 South African Symposium on Communications and Signal Processing-COMSIG '98 (Cat. No. 98EX214)","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133833507","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}
Pub Date : 1998-09-07DOI: 10.1109/COMSIG.1998.737009
L. Rowlinson, M. Summerton, Fethi Ahmed
Remote sensing is a cost- and time-effective technique for identifying alien vegetation in riparian zones. Remote sensing data can be incorporated into a geographic information system (GIS) which can be used as a tool for the management of riparian zones. In this paper, vegetation identification and classification techniques, such as aerial videography, aerial photography and satellite imagery, are identified and assessed in terms of accuracy for a small subcatchment in the KwaZulu-Natal midlands. This was achieved by incorporating the data obtained from different data sources into a GIS. Accuracies of the different techniques were then examined. The accuracy results obtained in this study indicate that using manual techniques to identify riparian vegetation from 1:10000 black-and-white aerial photographs yields the most accurate results.
{"title":"Comparison of remote sensing techniques for alien vegetation mapping","authors":"L. Rowlinson, M. Summerton, Fethi Ahmed","doi":"10.1109/COMSIG.1998.737009","DOIUrl":"https://doi.org/10.1109/COMSIG.1998.737009","url":null,"abstract":"Remote sensing is a cost- and time-effective technique for identifying alien vegetation in riparian zones. Remote sensing data can be incorporated into a geographic information system (GIS) which can be used as a tool for the management of riparian zones. In this paper, vegetation identification and classification techniques, such as aerial videography, aerial photography and satellite imagery, are identified and assessed in terms of accuracy for a small subcatchment in the KwaZulu-Natal midlands. This was achieved by incorporating the data obtained from different data sources into a GIS. Accuracies of the different techniques were then examined. The accuracy results obtained in this study indicate that using manual techniques to identify riparian vegetation from 1:10000 black-and-white aerial photographs yields the most accurate results.","PeriodicalId":294473,"journal":{"name":"Proceedings of the 1998 South African Symposium on Communications and Signal Processing-COMSIG '98 (Cat. No. 98EX214)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134368033","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}
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