Pub Date : 2007-12-01DOI: 10.1109/ELMAR.2007.4418801
M. Aquino, A. Dodson, G. deFranceschi, L. Alfonsi, V. Romano, J. Monico, H. Marques, C. Mitchell
The effect of the ionosphere on the signals of global navigation satellite systems (GNSS), such as the global positionig system (GPS) and the proposed European Galileo, is dependent on the ionospheric electron density, given by its total electron content (TEC). Ionospheric time-varying density irregularities may cause scintillations, which are fluctuations in phase and amplitude of the signals. Scintillations occur more often at equatorial and high latitudes. They can degrade navigation and positioning accuracy and may cause loss of signal tracking, disrupting safety-critical applications, such as marine navigation and civil aviation. This paper addresses the results of initial research carried out on two fronts that are relevant to GNSS users if they are to counter ionospheric scintillations, i.e. forecasting and mitigating their effects. On the forecasting front, the dynamics of scintillation occurrence were analysed during the severe ionospheric storm that took place on the evening of 30 October 2003, using data from a network of GPS ionospheric scintillation and TEC monitor (GISTM) receivers set up in Northern Europe. Previous results [I] indicated that GPS scintillations in that region can originate from ionospheric plasma structures from the American sector. In this paper we describe experiments that enabled confirmation of those findings. On the mitigation front we used the variance of the output error of the GPS receiver DLL (delay locked loop) to modify the least squares stochastic model applied by an ordinary receiver to compute position. This error was modelled, as a function of the S4 amplitude scintillation index measured by the GISTM receivers. An improvement of up to 21% in relative positioning accuracy was achieved with this technique.
{"title":"Towards forecasting and mitigating ionospheric scintillation effects on GNSS","authors":"M. Aquino, A. Dodson, G. deFranceschi, L. Alfonsi, V. Romano, J. Monico, H. Marques, C. Mitchell","doi":"10.1109/ELMAR.2007.4418801","DOIUrl":"https://doi.org/10.1109/ELMAR.2007.4418801","url":null,"abstract":"The effect of the ionosphere on the signals of global navigation satellite systems (GNSS), such as the global positionig system (GPS) and the proposed European Galileo, is dependent on the ionospheric electron density, given by its total electron content (TEC). Ionospheric time-varying density irregularities may cause scintillations, which are fluctuations in phase and amplitude of the signals. Scintillations occur more often at equatorial and high latitudes. They can degrade navigation and positioning accuracy and may cause loss of signal tracking, disrupting safety-critical applications, such as marine navigation and civil aviation. This paper addresses the results of initial research carried out on two fronts that are relevant to GNSS users if they are to counter ionospheric scintillations, i.e. forecasting and mitigating their effects. On the forecasting front, the dynamics of scintillation occurrence were analysed during the severe ionospheric storm that took place on the evening of 30 October 2003, using data from a network of GPS ionospheric scintillation and TEC monitor (GISTM) receivers set up in Northern Europe. Previous results [I] indicated that GPS scintillations in that region can originate from ionospheric plasma structures from the American sector. In this paper we describe experiments that enabled confirmation of those findings. On the mitigation front we used the variance of the output error of the GPS receiver DLL (delay locked loop) to modify the least squares stochastic model applied by an ordinary receiver to compute position. This error was modelled, as a function of the S4 amplitude scintillation index measured by the GISTM receivers. An improvement of up to 21% in relative positioning accuracy was achieved with this technique.","PeriodicalId":170000,"journal":{"name":"ELMAR 2007","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115843572","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 : 2007-10-25DOI: 10.1109/ELMAR.2007.4418817
I. Ipšić, Maja Matetic, Sanda Martinčić-Ipšić, A. Meštrović, M. Brkić
Speech technologies deal with designing computer systems that can recognize spoken words, comprehend human language and generate intelligible speech. There is a wide range of applications speech technology systems were successfully implemented in. One of the most complex applications in speech technology is a spoken dialog system, which can be used for information inquiry services. In the paper we present the work in the development of a spoken dialog system for Croatian language. We propose an approach for development of modules in a spoken dialog system for the limited domain which uses the same acoustic model for speech recognition and speech synthesis. For the linguistic analysis an approach is proposed which is based on qualitative language modelling, while the development of the dialog module is based on the formalism of the object-oriented frame logic language. Some experimental results for Croatian speech recognition and understanding are presented and discussed.
{"title":"Croatian speech technologies","authors":"I. Ipšić, Maja Matetic, Sanda Martinčić-Ipšić, A. Meštrović, M. Brkić","doi":"10.1109/ELMAR.2007.4418817","DOIUrl":"https://doi.org/10.1109/ELMAR.2007.4418817","url":null,"abstract":"Speech technologies deal with designing computer systems that can recognize spoken words, comprehend human language and generate intelligible speech. There is a wide range of applications speech technology systems were successfully implemented in. One of the most complex applications in speech technology is a spoken dialog system, which can be used for information inquiry services. In the paper we present the work in the development of a spoken dialog system for Croatian language. We propose an approach for development of modules in a spoken dialog system for the limited domain which uses the same acoustic model for speech recognition and speech synthesis. For the linguistic analysis an approach is proposed which is based on qualitative language modelling, while the development of the dialog module is based on the formalism of the object-oriented frame logic language. Some experimental results for Croatian speech recognition and understanding are presented and discussed.","PeriodicalId":170000,"journal":{"name":"ELMAR 2007","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122599394","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 : 2007-09-01DOI: 10.1109/ELMAR.2007.4418802
H. Strangeways, V. Gherm, N. Zernov
Ionospheric scintillations can not only reduce the accuracy of GPS/SB AS receiver pseudorange and carrier phase measurements but also result in a complete loss of lock on a satellite. Thus it is important to be able to investigate, model and mitigate scintillation effects. Thus, a transionospheric propagation model has been developed which can calculate frequency spectra (power spectra) of the phase and level (log-amplitude) fluctuations in a transionospheric channel of propagation containing time-varying electron density irregularities (which produce the scintillations) and which is valid even for strong scintillation conditions. The strongest amplitude scintillation occurs due to bubbles in the low latitude ionosphere. These have also been modelled and their effect on transionospheric GPS paths determined. Calculated power spectra of these processes can be used to produce random time sequences of the log-amplitude and phase of the field. Examples of simulations and their use are presented for high and low latitudes and scintillation mitigation for GPS receivers is discussed.
{"title":"Modeling and mitigation of the effect of scintillations on GPS","authors":"H. Strangeways, V. Gherm, N. Zernov","doi":"10.1109/ELMAR.2007.4418802","DOIUrl":"https://doi.org/10.1109/ELMAR.2007.4418802","url":null,"abstract":"Ionospheric scintillations can not only reduce the accuracy of GPS/SB AS receiver pseudorange and carrier phase measurements but also result in a complete loss of lock on a satellite. Thus it is important to be able to investigate, model and mitigate scintillation effects. Thus, a transionospheric propagation model has been developed which can calculate frequency spectra (power spectra) of the phase and level (log-amplitude) fluctuations in a transionospheric channel of propagation containing time-varying electron density irregularities (which produce the scintillations) and which is valid even for strong scintillation conditions. The strongest amplitude scintillation occurs due to bubbles in the low latitude ionosphere. These have also been modelled and their effect on transionospheric GPS paths determined. Calculated power spectra of these processes can be used to produce random time sequences of the log-amplitude and phase of the field. Examples of simulations and their use are presented for high and low latitudes and scintillation mitigation for GPS receivers is discussed.","PeriodicalId":170000,"journal":{"name":"ELMAR 2007","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125461858","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 : 2007-09-01DOI: 10.1109/ELMAR.2007.4418810
A. Begovic, N. Behlilovic
This paper researches changing of some basic parameters of symmetrical copper based twisted pair which is near the other twisted pair where active ADSL service exists. Analyzed parameters are: attenuation, signal to noise ratio, wideband noise and characteristic impedance. Analyzed subject is one pair in cable whose capacity is 100 x 2 x 0.4, with foamed polyethylene insulation and laminated polyethylene sheath. Existing ADSL service is sent through the different pairs in the observe cable and changes of the treated pair parameters are measured depending on the distance of the existing ADSL service from it. Obtained results are compared among themselves and with the parameters which are obtained in absence of ADSL service.
{"title":"Research of symmetrical copper based twisted pair near active ADSL service parameters properties","authors":"A. Begovic, N. Behlilovic","doi":"10.1109/ELMAR.2007.4418810","DOIUrl":"https://doi.org/10.1109/ELMAR.2007.4418810","url":null,"abstract":"This paper researches changing of some basic parameters of symmetrical copper based twisted pair which is near the other twisted pair where active ADSL service exists. Analyzed parameters are: attenuation, signal to noise ratio, wideband noise and characteristic impedance. Analyzed subject is one pair in cable whose capacity is 100 x 2 x 0.4, with foamed polyethylene insulation and laminated polyethylene sheath. Existing ADSL service is sent through the different pairs in the observe cable and changes of the treated pair parameters are measured depending on the distance of the existing ADSL service from it. Obtained results are compared among themselves and with the parameters which are obtained in absence of ADSL service.","PeriodicalId":170000,"journal":{"name":"ELMAR 2007","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125626985","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 : 2007-09-01DOI: 10.1109/ELMAR.2007.4418822
M. Swartling, M. Nilsson, N. Grbic
-This paper presents a method for automatically detecting vehicle mounted auditory reverse alarms, or other similar warning signals, based on hidden Markov model and pattern matching techniques. The method is designed for embedded realtime platforms. The purpose of the method is to embed it with active hearing protection devices, aiding the user in detecting warning signals in low SNR environments. Real recordings are used to evaluate the performance, and the results are presented.
{"title":"Detection of vehicle mounted auditory reverse alarm using hidden Markov model","authors":"M. Swartling, M. Nilsson, N. Grbic","doi":"10.1109/ELMAR.2007.4418822","DOIUrl":"https://doi.org/10.1109/ELMAR.2007.4418822","url":null,"abstract":"-This paper presents a method for automatically detecting vehicle mounted auditory reverse alarms, or other similar warning signals, based on hidden Markov model and pattern matching techniques. The method is designed for embedded realtime platforms. The purpose of the method is to embed it with active hearing protection devices, aiding the user in detecting warning signals in low SNR environments. Real recordings are used to evaluate the performance, and the results are presented.","PeriodicalId":170000,"journal":{"name":"ELMAR 2007","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133982630","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 : 2007-09-01DOI: 10.1109/ELMAR.2007.4418805
T. Grigorie, D. Sandu
The paper presents a study about the weight of the different errors of the gyro sensors in the error of attitude angles calculus. For study three types of gyros are selected in order to emphasize the differences in performance currently existing between these categories and the way in which these performances are reflected on to the errors of the attitude angles. To evaluate the errors, the gyros are modeled in Matlab/Simulink using the information from the data sheets and a Savage method to integrate the attitude equation is used. We will further emphasize the influences of noise, bias, gyros accuracy to measure different accelerations and scale factor's calibration error.
{"title":"The influences of the gyro sensors' errors on the attitude calculus","authors":"T. Grigorie, D. Sandu","doi":"10.1109/ELMAR.2007.4418805","DOIUrl":"https://doi.org/10.1109/ELMAR.2007.4418805","url":null,"abstract":"The paper presents a study about the weight of the different errors of the gyro sensors in the error of attitude angles calculus. For study three types of gyros are selected in order to emphasize the differences in performance currently existing between these categories and the way in which these performances are reflected on to the errors of the attitude angles. To evaluate the errors, the gyros are modeled in Matlab/Simulink using the information from the data sheets and a Savage method to integrate the attitude equation is used. We will further emphasize the influences of noise, bias, gyros accuracy to measure different accelerations and scale factor's calibration error.","PeriodicalId":170000,"journal":{"name":"ELMAR 2007","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115517974","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 : 2007-09-01DOI: 10.1109/ELMAR.2007.4418788
R. Prasad
Uniting computers, mobile phones, and personal devices is the goal of wireless personal area network (WPAN), which is meant to become a major part of future mobile communication network. Personal networks (PNs) extend the local scope of PANs by addressing virtual personal environments that span over a variety of communication architectures. PN is seen as the future for the wireless and mobile communications. This paper provides a brief overview ofPN, its basic concept, 'WPAN' and describes a relation between PN and the fourth generation (4G).
无线个人区域网络(wireless personal area network, WPAN)的目标是将计算机、移动电话和个人设备结合起来，成为未来移动通信网络的重要组成部分。个人网络(pn)通过处理跨越各种通信体系结构的虚拟个人环境，扩展了pan的本地范围。PN被视为无线和移动通信的未来。本文简要概述了无线网络及其基本概念“WPAN”，并描述了无线网络与第四代(4G)之间的关系。
{"title":"Personal networks and 4G","authors":"R. Prasad","doi":"10.1109/ELMAR.2007.4418788","DOIUrl":"https://doi.org/10.1109/ELMAR.2007.4418788","url":null,"abstract":"Uniting computers, mobile phones, and personal devices is the goal of wireless personal area network (WPAN), which is meant to become a major part of future mobile communication network. Personal networks (PNs) extend the local scope of PANs by addressing virtual personal environments that span over a variety of communication architectures. PN is seen as the future for the wireless and mobile communications. This paper provides a brief overview ofPN, its basic concept, 'WPAN' and describes a relation between PN and the fourth generation (4G).","PeriodicalId":170000,"journal":{"name":"ELMAR 2007","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116282353","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 : 2007-09-01DOI: 10.1109/ELMAR.2007.4418809
I. Radović, B. Modlic
This paper gives practical exploitation values for audio quality gain in GSM network with implemented AMR coding. Comparison with EFR/FR codecs is described. Investigation is performed for rural and urban areas. The comparison with theoretical values from 3GPP specifications is made as well.
{"title":"Practical results of AMR codecs exploitation in GSM network","authors":"I. Radović, B. Modlic","doi":"10.1109/ELMAR.2007.4418809","DOIUrl":"https://doi.org/10.1109/ELMAR.2007.4418809","url":null,"abstract":"This paper gives practical exploitation values for audio quality gain in GSM network with implemented AMR coding. Comparison with EFR/FR codecs is described. Investigation is performed for rural and urban areas. The comparison with theoretical values from 3GPP specifications is made as well.","PeriodicalId":170000,"journal":{"name":"ELMAR 2007","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125043422","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 : 2007-09-01DOI: 10.1109/ELMAR.2007.4418813
M. Cvitković, B. Modlic, G. Šišul
Data services are expected to have significant growth over the next few years and will likelly become the dominant source of 3G traffic. High speed downlink access (HSDPA) provides large enhancements over wideband code division multiple access (WCDMA) for the downlink. HSDPA was standardized as part of third generartion partnership project (3GPP) Relase 5 and Relase 6. The HSDPA peak date rate avaible in the terminals is initally 1.8 Mbps, and it is increasing to 3.6 and 7.2 Mbps with potentially beyond 10 Mbps. HSDPA has been designed to increase downlink packet data throughput by means of fast physical layer retransmission and transmission combining as well fast link adaptation controlled by the Node B -i.e. base transmission station (BTS). The paper covers HSDPA principles for WCDMA -the key new feature included in Relase 5 and enhanced further in Relase 6 specification.
{"title":"High Speed Downlink Packet Access Principles","authors":"M. Cvitković, B. Modlic, G. Šišul","doi":"10.1109/ELMAR.2007.4418813","DOIUrl":"https://doi.org/10.1109/ELMAR.2007.4418813","url":null,"abstract":"Data services are expected to have significant growth over the next few years and will likelly become the dominant source of 3G traffic. High speed downlink access (HSDPA) provides large enhancements over wideband code division multiple access (WCDMA) for the downlink. HSDPA was standardized as part of third generartion partnership project (3GPP) Relase 5 and Relase 6. The HSDPA peak date rate avaible in the terminals is initally 1.8 Mbps, and it is increasing to 3.6 and 7.2 Mbps with potentially beyond 10 Mbps. HSDPA has been designed to increase downlink packet data throughput by means of fast physical layer retransmission and transmission combining as well fast link adaptation controlled by the Node B -i.e. base transmission station (BTS). The paper covers HSDPA principles for WCDMA -the key new feature included in Relase 5 and enhanced further in Relase 6 specification.","PeriodicalId":170000,"journal":{"name":"ELMAR 2007","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132960466","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 : 2007-09-01DOI: 10.1109/ELMAR.2007.4418799
J. Barakovic, H. Bajric, A. Husic
Insufficient quality of service (QoS) of the emerging multimedia applications is a growing concern that has led the need for research and study. In this paper we investigate the impact of increased video traffic on QoS parameters and their correlation in next generation network. Multi-protocol label switching (MPLS) and differentiated services (DiffServ) integration is very useful strategy for today's traffic. MPLS Traffic Engineering (TE) plays an important role in the implementation of network services with QoS guarantees. The aim of simulation study is to underline how MPLS TE and MPLS Diffserv integration improve the performances of today's networks, and identify opportunities for improvement, and development of new mechanisms to ensure QoS features in future networks.
{"title":"The impact of increased video traffic on quality of service parameters in next generation IP/MPLS network","authors":"J. Barakovic, H. Bajric, A. Husic","doi":"10.1109/ELMAR.2007.4418799","DOIUrl":"https://doi.org/10.1109/ELMAR.2007.4418799","url":null,"abstract":"Insufficient quality of service (QoS) of the emerging multimedia applications is a growing concern that has led the need for research and study. In this paper we investigate the impact of increased video traffic on QoS parameters and their correlation in next generation network. Multi-protocol label switching (MPLS) and differentiated services (DiffServ) integration is very useful strategy for today's traffic. MPLS Traffic Engineering (TE) plays an important role in the implementation of network services with QoS guarantees. The aim of simulation study is to underline how MPLS TE and MPLS Diffserv integration improve the performances of today's networks, and identify opportunities for improvement, and development of new mechanisms to ensure QoS features in future networks.","PeriodicalId":170000,"journal":{"name":"ELMAR 2007","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133574853","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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