Pub Date : 1998-09-07DOI: 10.1109/COMSIG.1998.736915
W. Wilson, M. Winter, C. Nohr, F. Aghdasi
Fast Fourier transformation (FFT) of the auditory brainstem response (ABR) has proven useful in improving this tests sensitivity and specificity as a diagnostic assessment tool, but has suffered from poor control of pre-FFT windowing procedures. This study compared the clinical significance, as versus the obvious mathematical significance, of using no Blackman, and modified Blackman window techniques for FFT analysis of ABRs in normal subjects. Windowing was shown to statistically reduce ABR FFT magnitudes with the differences between window results all being clinically significant. These findings warn against the clinical comparison of ABR FFT results obtained using different windows and reinforces the need to state specifically the FFT procedures used when conducting clinical ABR frequency analysis.
{"title":"Signal processing of the auditory brainstem response: clinical effects of variations in fast Fourier transform analysis","authors":"W. Wilson, M. Winter, C. Nohr, F. Aghdasi","doi":"10.1109/COMSIG.1998.736915","DOIUrl":"https://doi.org/10.1109/COMSIG.1998.736915","url":null,"abstract":"Fast Fourier transformation (FFT) of the auditory brainstem response (ABR) has proven useful in improving this tests sensitivity and specificity as a diagnostic assessment tool, but has suffered from poor control of pre-FFT windowing procedures. This study compared the clinical significance, as versus the obvious mathematical significance, of using no Blackman, and modified Blackman window techniques for FFT analysis of ABRs in normal subjects. Windowing was shown to statistically reduce ABR FFT magnitudes with the differences between window results all being clinically significant. These findings warn against the clinical comparison of ABR FFT results obtained using different windows and reinforces the need to state specifically the FFT procedures used when conducting clinical ABR frequency analysis.","PeriodicalId":294473,"journal":{"name":"Proceedings of the 1998 South African Symposium on Communications and Signal Processing-COMSIG '98 (Cat. No. 98EX214)","volume":"13 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":"114232290","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.1998.736996
I. Theron, J. Cloete
This paper deals with the design of slotted waveguide arrays at Ka-band (38 GHz). Practical machining tolerances are considered. In order to achieve low sidelobes throughout it is critical that the centre line of the waveguide broad wall is determined very accurately. An error in this position results in systematic errors in the excitation of the slots. This leads to grating lobe like side lobes, the level of which depends on the amount of misplacement. However, the angle at which the side lobe occurs is independent of the position error.
{"title":"On slotted waveguide antenna design at Ka-band","authors":"I. Theron, J. Cloete","doi":"10.1109/COMSIG.1998.736996","DOIUrl":"https://doi.org/10.1109/COMSIG.1998.736996","url":null,"abstract":"This paper deals with the design of slotted waveguide arrays at Ka-band (38 GHz). Practical machining tolerances are considered. In order to achieve low sidelobes throughout it is critical that the centre line of the waveguide broad wall is determined very accurately. An error in this position results in systematic errors in the excitation of the slots. This leads to grating lobe like side lobes, the level of which depends on the amount of misplacement. However, the angle at which the side lobe occurs is independent of the position error.","PeriodicalId":294473,"journal":{"name":"Proceedings of the 1998 South African Symposium on Communications and Signal Processing-COMSIG '98 (Cat. No. 98EX214)","volume":"16 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":"114375590","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.1998.736936
S. Levitt, F. Aghdasi
In this paper we examine the applicability of the wavelet transform and image scaling to the detection of buildings in monocular, greyscale aerial photography. Both of these techniques have strong frequency domain interpretations and thus differ from the traditional methods used in building extraction systems. Our results from employing the different techniques indicate that both the high and low frequency components of an aerial image offer useful information for the detection of buildings and other man-made features.
{"title":"An investigation into the use of wavelets and scaling for the extraction of buildings in aerial images","authors":"S. Levitt, F. Aghdasi","doi":"10.1109/COMSIG.1998.736936","DOIUrl":"https://doi.org/10.1109/COMSIG.1998.736936","url":null,"abstract":"In this paper we examine the applicability of the wavelet transform and image scaling to the detection of buildings in monocular, greyscale aerial photography. Both of these techniques have strong frequency domain interpretations and thus differ from the traditional methods used in building extraction systems. Our results from employing the different techniques indicate that both the high and low frequency components of an aerial image offer useful information for the detection of buildings and other man-made features.","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":"126854796","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.1998.737003
A. Langman, M. R. Inggs
For the past few decades ground penetrating radar (GPR) has been recognised as one of the most promising technologies to aid in the detection of landmines. Most of the commercially available radars are pulsed systems. With the rapid development of digital radio technology, stepped frequency continuous wave (SFCW) modulation techniques are becoming more feasible. A carefully designed SFCW radar offers numerous advantages over the pulsed systems for the short range measurements. This paper discusses the design and testing of a 1-2 GHz SFCW radar system. Measurements of various mine simulants from an indoor and outdoor test site are presented.
{"title":"A 1-2 GHz SFCW radar for landmine detection","authors":"A. Langman, M. R. Inggs","doi":"10.1109/COMSIG.1998.737003","DOIUrl":"https://doi.org/10.1109/COMSIG.1998.737003","url":null,"abstract":"For the past few decades ground penetrating radar (GPR) has been recognised as one of the most promising technologies to aid in the detection of landmines. Most of the commercially available radars are pulsed systems. With the rapid development of digital radio technology, stepped frequency continuous wave (SFCW) modulation techniques are becoming more feasible. A carefully designed SFCW radar offers numerous advantages over the pulsed systems for the short range measurements. This paper discusses the design and testing of a 1-2 GHz SFCW radar system. Measurements of various mine simulants from an indoor and outdoor test site are presented.","PeriodicalId":294473,"journal":{"name":"Proceedings of the 1998 South African Symposium on Communications and Signal Processing-COMSIG '98 (Cat. No. 98EX214)","volume":"22 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":"126522257","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.1998.736914
W. Wilson, M. Winter, G. Kerr, F. Aghdasi
Multiresolutional wavelet analysis of the auditory brainstem response (ABR) in the time frequency domain (TFD) has immense potential for improving this test's sensitivity and specificity as a diagnostic assessment tool, but the choice of wavelet remains a problem. This study compared the clinical significance, as versus the obvious mathematical significance, of using Daubechies 5, symlet 4, and biorthogonal 3.5 wavelet techniques to obtain ABR TFD results in normal subjects. The wavelet techniques showed multiple statistical differences between their TFD results, with a significant number being clinically significant, particularly for TFD component amplitudes. These findings warn against the clinical comparison of TFD ABR results obtained using different wavelets and reinforces the need to state specifically the wavelet procedures used when conducting clinical ABR multiresolutional wavelet analysis.
{"title":"Signal processing of the auditory brainstem response: investigation into the use of discrete wavelet analysis","authors":"W. Wilson, M. Winter, G. Kerr, F. Aghdasi","doi":"10.1109/COMSIG.1998.736914","DOIUrl":"https://doi.org/10.1109/COMSIG.1998.736914","url":null,"abstract":"Multiresolutional wavelet analysis of the auditory brainstem response (ABR) in the time frequency domain (TFD) has immense potential for improving this test's sensitivity and specificity as a diagnostic assessment tool, but the choice of wavelet remains a problem. This study compared the clinical significance, as versus the obvious mathematical significance, of using Daubechies 5, symlet 4, and biorthogonal 3.5 wavelet techniques to obtain ABR TFD results in normal subjects. The wavelet techniques showed multiple statistical differences between their TFD results, with a significant number being clinically significant, particularly for TFD component amplitudes. These findings warn against the clinical comparison of TFD ABR results obtained using different wavelets and reinforces the need to state specifically the wavelet procedures used when conducting clinical ABR multiresolutional wavelet analysis.","PeriodicalId":294473,"journal":{"name":"Proceedings of the 1998 South African Symposium on Communications and Signal Processing-COMSIG '98 (Cat. No. 98EX214)","volume":" 39","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132074545","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.1998.736935
B.A. Alaylioglu, F. Aghdasi
The presence of microcalcification clusters (MCCs) is a primary sign of breast cancer. Thus, the successful detection of microcalcifications during mammographic examination is vital for the early diagnosis of the cancer. Computer-based detection methods aim to ameliorate the diagnostic process by providing the radiologist with a second opinion. An automatic detection scheme making use of a neural network classifier, with input feature vectors containing spatial and spectral image attributes, is investigated. A wavelet-based image enhancement technique is employed to improve the detection. The detection scheme is tested and preliminary results are reported.
{"title":"An artificial neural network for detecting microcalcifications in wavelet-enhanced digitised mammograms","authors":"B.A. Alaylioglu, F. Aghdasi","doi":"10.1109/COMSIG.1998.736935","DOIUrl":"https://doi.org/10.1109/COMSIG.1998.736935","url":null,"abstract":"The presence of microcalcification clusters (MCCs) is a primary sign of breast cancer. Thus, the successful detection of microcalcifications during mammographic examination is vital for the early diagnosis of the cancer. Computer-based detection methods aim to ameliorate the diagnostic process by providing the radiologist with a second opinion. An automatic detection scheme making use of a neural network classifier, with input feature vectors containing spatial and spectral image attributes, is investigated. A wavelet-based image enhancement technique is employed to improve the detection. The detection scheme is tested and preliminary results are reported.","PeriodicalId":294473,"journal":{"name":"Proceedings of the 1998 South African Symposium on Communications and Signal Processing-COMSIG '98 (Cat. No. 98EX214)","volume":"6 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":"125122113","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.1998.736926
N. van der Merwe, A. Hoffman
The selection and preprocessing of features are crucial to the success of a classifier for pattern recognition applications. The preprocessing often involves filters, transformations and non-linear processing of the raw data. Since the training data required is an exponential function of the number of features, a reduction or transformation of the features is essential. While it is frequently possible to heuristically select reasonable values pertaining to the selection of these parameters, an automated approach could be of great value in different application areas. Various factors relating to the optimization process are described and the results of continuous wavelet based optimization on seismic buffer recognition are described.
{"title":"Closed loop optimization of features for neural classifiers","authors":"N. van der Merwe, A. Hoffman","doi":"10.1109/COMSIG.1998.736926","DOIUrl":"https://doi.org/10.1109/COMSIG.1998.736926","url":null,"abstract":"The selection and preprocessing of features are crucial to the success of a classifier for pattern recognition applications. The preprocessing often involves filters, transformations and non-linear processing of the raw data. Since the training data required is an exponential function of the number of features, a reduction or transformation of the features is essential. While it is frequently possible to heuristically select reasonable values pertaining to the selection of these parameters, an automated approach could be of great value in different application areas. Various factors relating to the optimization process are described and the results of continuous wavelet based optimization on seismic buffer recognition are described.","PeriodicalId":294473,"journal":{"name":"Proceedings of the 1998 South African Symposium on Communications and Signal Processing-COMSIG '98 (Cat. No. 98EX214)","volume":"85 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":"121236343","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.1998.736993
E. Botha, J. Joubert
A genetic algorithm is proposed to obtain a good starting pattern for numerical array synthesis methods. This approach differs from others in that a starting point as close as possible to the global minimum is searched.
{"title":"A warm start for numerical antenna array synthesis methods","authors":"E. Botha, J. Joubert","doi":"10.1109/COMSIG.1998.736993","DOIUrl":"https://doi.org/10.1109/COMSIG.1998.736993","url":null,"abstract":"A genetic algorithm is proposed to obtain a good starting pattern for numerical array synthesis methods. This approach differs from others in that a starting point as close as possible to the global minimum is searched.","PeriodicalId":294473,"journal":{"name":"Proceedings of the 1998 South African Symposium on Communications and Signal Processing-COMSIG '98 (Cat. No. 98EX214)","volume":"17 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":"121245751","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.1998.736944
W. Penzhorn
The linear complexity of a binary sequences is an important attribute in applications such as secure communications. In this article we introduce the concept of quadratic complexity of a binary sequences. It is shown that this complexity measure is closely linked to the theory of primitive Reed-Muller codes. Making use of the parity-check polynomial h(x) of a Reed-Muller code, a new algorithm for the computation of the quadratic complexity profile of a sequence is developed. Experimental results confirm the close resemblance between expected theoretical and practical behaviour.
{"title":"Quadratic complexity of binary sequences","authors":"W. Penzhorn","doi":"10.1109/COMSIG.1998.736944","DOIUrl":"https://doi.org/10.1109/COMSIG.1998.736944","url":null,"abstract":"The linear complexity of a binary sequences is an important attribute in applications such as secure communications. In this article we introduce the concept of quadratic complexity of a binary sequences. It is shown that this complexity measure is closely linked to the theory of primitive Reed-Muller codes. Making use of the parity-check polynomial h(x) of a Reed-Muller code, a new algorithm for the computation of the quadratic complexity profile of a sequence is developed. Experimental results confirm the close resemblance between expected theoretical and practical behaviour.","PeriodicalId":294473,"journal":{"name":"Proceedings of the 1998 South African Symposium on Communications and Signal Processing-COMSIG '98 (Cat. No. 98EX214)","volume":"4 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":"121285615","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.1998.736975
G. W. Milne
The most frequent use of co-axial cable is to prevent electrical noise entering signals being passed between equipment. Ground voltage differences are common and add in series with the signal voltage. The screen of co-axial cable grounded at both ends induces a voltage in the inner conductor which cancels higher frequency ground voltage differences, starting from a break point of typically 2 kHz. The signal current also produces a flux external to the screen, which induces a loop current through the screen and earth path which opposes the earth current. Signal currents above 2 kHz thus increasingly return through the screen, in spite of a lower impedance ground path. An equivalent circuit explains the phenomenon and the extreme sensitivity of co-axial and oscilloscope probes to short pigtail leads. Experiments are described and data presented which justify the theory. Remarks are made on end connections, cable trays, and feeding power lines via co-axial cable.
{"title":"Ground voltage and current cancellation by co-axial cable","authors":"G. W. Milne","doi":"10.1109/COMSIG.1998.736975","DOIUrl":"https://doi.org/10.1109/COMSIG.1998.736975","url":null,"abstract":"The most frequent use of co-axial cable is to prevent electrical noise entering signals being passed between equipment. Ground voltage differences are common and add in series with the signal voltage. The screen of co-axial cable grounded at both ends induces a voltage in the inner conductor which cancels higher frequency ground voltage differences, starting from a break point of typically 2 kHz. The signal current also produces a flux external to the screen, which induces a loop current through the screen and earth path which opposes the earth current. Signal currents above 2 kHz thus increasingly return through the screen, in spite of a lower impedance ground path. An equivalent circuit explains the phenomenon and the extreme sensitivity of co-axial and oscilloscope probes to short pigtail leads. Experiments are described and data presented which justify the theory. Remarks are made on end connections, cable trays, and feeding power lines via co-axial cable.","PeriodicalId":294473,"journal":{"name":"Proceedings of the 1998 South African Symposium on Communications and Signal Processing-COMSIG '98 (Cat. No. 98EX214)","volume":"26 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":"116336045","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：