The research investigates the influence on the human body on a communication system. To understand this, the effect of hands free kit (HFK) on energy absorption in the body was investigated when operating a smart phone at 2G. Findings on the research are given in the thesis report. Also, the influence of the way in which a phone is held on a phone s received power was investigated. The result was compared to that obtained using a hand phantom acquired from SPEAG. This was to check if the hand phantom best represents the human hand when using it in experiments. The setup for the experiment was in an anechoic chamber at Loughborough University. The mobile phone transmitted in the 2G system. In further experiments carried out on the body, two antennas were attached to the body in six different orientations to receive power from a source creating a Single Input Multiple Output (SIMO) system. The antennas used were monopoles mounted on a circular ground plane. These antennas were designed and constructed with the influence of the body taken into consideration. The use of diversity techniques to improve transmission to an on-body system is investigated with the antennas on the body. For each alignment, the transmission to the on-body was compared with the transmission to the corresponding off-body (free space). Experiments for this work were carried out in three environments.

No description available.

"Speech enhancement in an automobile is a challenging problem because interference can come from engine noise, fans, music, wind, road noise, reverberation, echo, and passengers engaging in other conversations. Hands-free microphones make the situation worse because the strength of the desired speech signal reduces with increased distance between the microphone and talker. Automobile safety is improved when the driver can use a hands-free interface to phones and other devices instead of taking his eyes off the road. The demand for high quality hands-free communication in the automobile requires the introduction of more powerful algorithms. This thesis shows that a unique combination of five algorithms can achieve superior speech enhancement for a hands-free system when compared to beamforming or spectral subtraction alone. Several different designs were analyzed and tested before converging on the configuration that achieved the best results. Beamforming, voice activity detection, spectral subtraction, perceptual nonlinear weighting, and talker isolation via pitch tracking all work together in a complementary iterative manner to create a speech enhancement system capable of significantly enhancing real world speech signals. The following conclusions are supported by the simulation results using data recorded in a car and are in strong agreement with theory. Adaptive beamforming, like the Generalized Side-lobe Canceller (GSC), can be effectively used if the filters only adapt during silent data frames because too much of the desired speech is cancelled otherwise. Spectral subtraction removes stationary noise while perceptual weighting prevents the introduction of offensive audible noise artifacts. Talker isolation via pitch tracking can perform better when used after beamforming and spectral subtraction because of the higher accuracy obtained after initial noise removal. Iterating the algorithm once increases the accuracy of the Voice Activity Detection (VAD), which improves the overall performance of the algorithm. Placing the microphone(s) on the ceiling above the head and slightly forward of the desired talker appears to be the best location in an automobile based on the experiments performed in this thesis. Objective speech quality measures show that the algorithm removes a majority of the stationary noise in a hands-free environment of an automobile with relatively minimal speech distortion."

Today the effective use of computers (e.g. those with Internet browsers and graphical interfaces) involves the use of some sort of cursor control like what a mouse provides. However, a standard mouse is not always the best option for all users. There are currently many devices available to provide alternative computer access. These devices may be divided into categories: brain-computer interfaces (BCI), mouth-based controls, camera-based controls, and head-tilt controls. There is no single solution as each device and application has to be tailored to each user's unique preferences and abilities. Furthermore, each device category has certain strengths and weaknesses that need to be considered when making an effective match between a user and a device. One problem that remains is that these alternative input devices do not perform as well when compared to standard mouse devices. To help with this, assistive user interface techniques can be employed. While research shows that these techniques help, most require that modifications be made to the user interfaces or that a user's intended target be known beforehand by the host computer. In this research, a novel target-agnostic assistive user interface algorithm intended to improve usage performance for both head-operated and standard mouse devices is designed, implemented (as a mouse device driver and in host computer software) and experimentally evaluated. In addition, a new wireless head-operated input device requiring no special host computer hardware, is designed, built and evaluated. It was found that the Virtual Dynamic Tunnel algorithm improved performance for a standard mouse in straight tunnel trials and that nearly 60% of users would be willing to use the head-tilt mouse as a hands-free option for cursor control.

BACKGROUND: In order to maintain non-weight bearing restrictions of the lower extremity, an assistive device must be utilized. Currently most devices require the restricted limb to be held in a static position while the contralateral extremity provides forward propulsion. Atrophy and disuse conditions ensue rapidly, slowing healing and prolonging recovery. A hands-free single crutch (HFSC) utilizes both lower extremities, potentially reducing atrophy. The purpose of this study was to examine the Electromyography (EMG) differences between a HFSC and standard axillary crutches (SAC). METHODS: A prospective, crossover study was performed using 21 healthy volunteers from an active duty foot and ankle clinic. Demographic data was obtained and then subjects were fitted with a HFSC and SAC. Wireless surface EMG sensors were applied to the belly of the rectus femoris (RF), vastus lateralis (VL), lateral gastrocnemius (LG), and the gluteus maximus (GM) by a board-certified orthopedic surgeon. Subjects then ambulated at a self-selected velocity for 30 meters, while 15 seconds of the gait cycle was recorded for each device. Mean muscle activity and the maximum voluntary isometric contraction (MVIC) were recorded. RESULTS: The RF, GM, and LG showed statistically significant increased levels of muscle activity while using the HFSC compared to SAC (respectively P = 0.05, P = 0.03, P = 0.03). The VL did not show statistically higher muscle activity while using the HFSC (P = 0.051). The RF, GM, and VL showed statistically significant higher MVIC percentages while using the HFSC compared to using SAC (respectively P = 0.005, P = 0.005, P = 0.013). The LG did not show statistically higher MVIC percentage while using the HFSC (P = 0.076). CONCLUSION: The HFSC subjects demonstrated increased muscle recruitment and intensity while maintaining cyclic contractions consistent with bipedal gait pattern. SAC demonstrated less recruitment and intensity with an isometric pattern regardless of the phase of gait. / 2022-06-04T00:00:00Z

Echo in telephones is generally undesirable but inevitable. There are two possible sources of echo in a telephone system. The impedance mismatch in hybrids generates network (electric) echo. The acoustic coupling between loudspeaker and microphone, in hands-free telephones, produces acoustic echo. Echo cancelers are used to control these echoes. In this thesis, we analyze the Least Mean Squares (LMS), Normalized LMS (NLMS), Recursive Least Squares (RLS), and Subband NLMS (SNLMS) algorithms, and evaluate their performance as acoustic and network echo cancelers. The algorithms are compared based on their convergence rate, steady state echo return loss (ERL), and complexity of implementation. While LMS is simple, its convergence rate is dependent on the eigenvalue spread of the signal. In particular, it converges slowly with speech as input. This problem is mitigated in NLMS. The complexity of NLMS is comparable to that of LMS. The convergence rate of RLS is independent of the eigenvalue spread, and it has the fastest convergence. On the other hand, RLS is highly computation intensive. Among the four algorithms considered here, SNLMS has the least complexity of implementation, as well as the slowest rate of convergence. Switching between the NLMS and SNLMS algorithms is used to achieve fast convergence with low computational requirements. For a given computational power, it is shown that switching between algorithms can give better performance than using either of the two algorithms exclusively, especially in rooms with long reverberation times. We also discuss various implementation issues associated with an integrated echo cancellation system, such as double-talk detection, finite precision effects, nonlinear processing, and howling detection and control. The use of a second adaptive filter is proposed, to reduce near-end ambient noise. Simulation results indicate that this approach can reduce the ambient noise by about 20 dB. A configuration is presented for the real time single-chip DSP implementation of acoustic and network echo cancelers, and an interface between the echo canceler and the telephone is proposed. Finally, some results obtained from simulations and implementations of individual modules, on the TMS320C31 and ADSP 2181 processors, are reported. The real time NLMS DSP implementations provide 15 dB of echo return loss. / Master of Science

Speech processing in the automotive environment is a challenging problem due to the presence of powerful and unpredictable nonstationary noise. This thesis addresses two detection problems involving both nonstationary noise signals and nonstationary desired signals. Two detectors are developed: one to detect passing vehicle noise in the presence of speech and one to detect speech in the presence of passing vehicle noise. The latter is then measured against a state-of-the-art voice activity detector used in telephony. The process of compiling a library of recordings in the automobile to facilitate this research is also detailed.

In its theoretical part, this thesis treats possibilities of using no-touch technology Leap Motion in elementary school lessons for operating interactive applications focused on physics education. The thesis investigates the ways in which it is possible to operate already published applications which are not programmed specifically for a no-touch technology and which are, however, intended for work with an interactive whiteboard or for a standard computer work. Their advantages and disadvantages are discussed as well. The thesis deals, among other things, with the availability of relevant applications and offers a summary of information about Leap Motion technology and of opportunities for replacing interactive whiteboards. The thesis also includes a description of the technology and of the potential for developing your own applications. The aim of the practical part is to create a new didactic application which will be tested in lessons. This part also includes a poll which will find out what is the interest in Leap Motion technology among teachers.

Tato diplomová práce se zabývá problematikou implementace Hands-Free komunikačních systémů v automobilovém průmyslu. První kapitola je zaměřena na teoretické aspekty zpracování řeči v embedded aplikacích, jako je potlačení šumu, potlačení akustické zpětné vazby a další faktory ovlivňující kvalitu Hands-Free systémů. Druhá kapitola obsahuje návrh kompaktního flexibilního mobilního testovacího zařízení pro bezdrátové komunikační Hands-Free moduly.

Introduction: The introduction presents concepts around hands-free interactions. Furthermore, topics of digitalization, value co-creation, and how technology suppliers and end-users co-create value through the application of eye-tracking is described. Problem discussion: Healthcare is a complex system and is becoming more accustomed to the value co-creation concept with all types of stakeholders. New technologies are needed in healthcare to ensure positive patient outcomes and sterility. These technologies appear in hands-free devices such as eye-tracking technology. Limited research is found on interactions between healthcare practitioners and/or researchers with technology providers with key actors as suppliers and practitioners. Looking further at value co-creation, to achieve hands-free healthcare, it is necessary to fully utilize nascent digital technologies while incorporating them into digitalized processes. Hence, additional study is needed to investigate how key actors co-create value and promote the full use of advanced technologies. Purpose and Research Question: The purpose of this study is to understand how value is co-created by the application of hands-free devices in healthcare settings. To do that, we explore the activities performed by technology suppliers and technology end-users (healthcare practitioners and researchers) that enable value co-creation through the application of eye-tracking devices in hands-free healthcare. This study seeks to answer the research question: How do technology suppliers and end-users co-create value through the application of eye-tracking in hands-free healthcare? Theoretical Framework: Theoretical Framework was established based on scientific literature. Furthermore, it is split between concepts of value-in-use, value co-production, and two stages of digitalization, where the first stage is digitalization of products and services, the second stage is digitalization of activities and decisions. Methodology: In this thesis, qualitative descriptive research with a deductive approach is followed. Empirical data was collected through three exploratory and ten semi-structured interviews, where six semi-structured interviews were conducted with suppliers (primary data) who are employed in an eye-tracking supplying company, and four end-users (supportive data), which are healthcare practitioners and/or researchers. Findings & Analysis: Here, findings gathered from primary (technology suppliers), supportive (end-users), and secondary sources (documents) were analyzed and compared to the literature and theoretical framework. Conclusion: Concluding, 20 activities were found for the value co-production part of the research and 23 activities for the value-in-use part. Some of the found activities could not be supported by scientific literature or framework and are explained as additional findings.