1,720,977 research outputs found
Investigation of indoor localization with ambient FM radio stations
Full text linkLocalization plays an essential role in many ubiquitous computing applications. While the outdoor location-aware services based on GPS are becoming increasingly popular, their proliferation to indoor environments is limited due to the lack of widely available indoor localization systems. The de-facto standard for indoor positioning is based on Wi-Fi and while other localization alternatives exist, they either require expensive hardware or provide a low accuracy. This paper presents an investigation into localization system that leverages signals of broadcasting FM radio stations. The FM stations provide a worldwide coverage, while FM tuners are readily available in many mobile devices. The experimental results show that FM radio can be used for indoor localization, while providing longer battery life than Wi-Fi, making FM an alternative to consider for positioning
Indoor Localization Using Audio Features of FM Radio Signals
Full text linkTypical localization systems use various features of the signal to estimate the distance, including received signal strength indicator (RSSI), timing information or angle of arrival (AoA). However, there are a number of signal features of FM radio that may also be suitable for localization, namely stereo channel separation (SCS) and signal to noise ratio (SNR). This paper investigates the feasibility of indoor localization using fingerprinting of audio features of FM radio signals emitted by low-power FM transmitters using SNR and SCS values. The experimental results demonstrate the possibility of audio-based localization, when signal strength readings are not available
Smart Phone Sensing to Examine Effects of Social Interactions and Non-sedentary Work Time on Mood Changes
Full text linkThe typical approach taken by clinical studies examining the factors that affect mood is to use questionnaires in order to record the activities that impact the mood. However, recording activities in this manner suffers from a number of issues including floor effect and difficulty in recalling past activities. Our work instead has focused on using unobtrusive monitoring technology to study mood changes during office hours and two associated factors that influence these changes, namely social activity and non-sedentary patterns. The pilot study ran over the course of 7 days of measurements with the participation of 9 knowledge workers. The results have shown that mood changes are highly correlated with both social interactions and non-sedentary work style. This study is the first to investigate the correlation between mood changes and non-sedentary behavior patterns, opening up a research avenue to explore psychological effects of increasing prevalence of sedentary behavior
FM radio for indoor localization with spontaneous recalibration
No full textThe position of mobile users has become highly important information in pervasive computing environments. Indoor localization systems based on Wi–Fi signal strength fingerprinting techniques are widely used in office buildings with an existing Wi–Fi infrastructure. Our previous work has proposed a solution based on exploitation of a FM signal to deal with environments not covered with Wi–Fi signal or environments with only a single Wi–Fi access point. However, a general problem of indoor wireless positioning systems pertains to signal degradation due to the environmental factors affecting signal propagation. Therefore, in order to maintain a desirable level of localization accuracy, it becomes necessary to perform periodic calibrations of the system, which is either time consuming or requires dedicated equipment and expert knowledge. In this paper, we present a comparison of FM versus Wi–Fi positioning systems and a combination of both systems, exploiting their strengths for indoors positioning. We also address the problem of recalibration by introducing a novel concept of spontaneous recalibration and demonstrate it using the FM localization system. Finally, the results related to device orientation and localization accuracy are discussed
Indoor positioning and floor plan based ground truth: Can you really click where you are?
Full text linkpeer reviewedThe increasing accuracy of indoor positioning systems requires an appropriately accurate evaluation, which compares system outputs with the known coordinates of test locations --- the ground truth. Although ground truth data are rarely (if ever) tested, they are traditionally assumed to be perfectly accurate. However, even small errors introduced by inaccurate ground truth need to be taken into account for fair evaluation and comparison between modern high-resolution positioning systems.
In this paper we analyze the quality of ground truth data provided by clicking on an interactive floor plan (a method employed by such classical systems as RADAR and Horus). Experimental results show that this method has high precision but low accuracy, and high systematic errors make it unsuitable for evaluation of fine-grained localization systems.INDOOR
Indoor positioning using FM radio signals
No full textLocation based services are becoming an indispensable part of the life. Wide adoption of the Global Positioning System in mobile devices, combined with Wi-Fi and cellular networks, have practically solved the problem of outdoor localization and opened a new market. This, however, is the case only for outdoors. There are numerous areas of ubiquitous computing, which require the knowledge of user position indoors. Awareness of user's location is important in such areas as smart environments, assisted daily living, behaviour analysis studies.
Over the past years, a significant effort has been dedicated to development of indoor localization systems. The results vary in characteristics, performance, and cost. Despite the effort, the existing indoor positioning systems are still limited: they either require expensive infrastructure (UWB, ultrasound), have limited coverage (Wi-Fi, Bluetooth, RFID, DECT) or low accuracy (cellular networks). The cost of commercial systems is prohibitive for their wide adoption (Ubisense).
The main objective of this thesis was to determine the feasibility of indoor positioning using FM radio signals, generated either by local transmitters or by broadcasting FM stations. The performance of FM localization cannot be simply predicted from other technologies, such as Wi-Fi or GSM, due to significantly lower frequencies (around 100~MHz vs. units of GHz) leading to differences in signal propagation. Moreover, FM represents a popular and well-established technology, readily available in many mobile devices. At the infrastructure side, broadcasting FM stations provide almost ubiquitous coverage, while short-range FM transmitters are available license-free from conventional electronics markets.
The results indicate that indoor positioning using broadcasting FM stations outperforms in terms of accuracy both Wi-Fi and GSM indoor localization systems (for confidence levels up to 90% and in all cases, respectively). Due to the passive nature of the client devices, the system can be used in sensitive areas where local radio transmission, such as Wi-Fi or GSM, is prohibited for safety or security reasons. Finally, an FM receiver has significantly lower power consumption than a Wi-Fi module and provides 2.6 to 5.5 times longer battery life in localization mode
AmbiLoc: A year-long dataset of FM, TV and GSM fingerprints for ambient indoor localization
Full text linkpeer reviewedAmbient indoor localization - an approach that leverages ambient radio signals - has been previously shown to provide promising positioning performance using the globally available infrastructure of FM, TV and cellular stations. However, the need for specialized equipment and laborious data collection constitute a high entry barrier for follow-up studies.
This paper presents AmbiLoc - a dataset of radio signals for ambient indoor localization research. The dataset has been systematically collected in multiple testbeds, including large-scale and multi-floor buildings, over the course of one year. Due to the use of a software-defined radio receiver, raw signal samples in AmbiLoc allow extraction of arbitrary fingerprinting features. The first edition of AmbiLoc, introduced in this paper, includes received signals strength (RSS) fingerprints of FM, TV and GSM signals, along with the relevant metadata (such as weather conditions). The dataset is available online at AmbiLoc.org.
As the first public dataset of ambient localization signals, AmbiLoc provides an easy entry and a common reference for researchers exploring novel indoor localization methods
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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