Many solutions and projects proposed within the Ambient Assisted Living research area, aim at monitoring the degree of vitality of elderly users in their daily activities, and in their home environment, to possibly avoid or strongly limit the need for clinical evaluations. In fact, the information on the subject's vitality, manifested through his/her activity profile, may be used to evaluate possible anomalous trends, related to cognitive or physical decay. For such a kind of analysis to be realistically affordable, the monitoring device shall be unobtrusive, and transparent to the user. With the aim of striving for the simplest and most reliable design compatible with the aforementioned requirements, this paper presents a wearable device equipped with a sensing insole hosting force sensors, and the related electronics for signal processing and data transmission. The device locally classifies different dynamic states (sitting, walking, standing) and transmits the corresponding information to a supervising system. Preliminary experimental results confirm the effectiveness of the approach, in correctly detecting and classifying the user's activities.
Spread spectrum techniques, originally conceived to counteract the effects of noise and interference, have enabled the development of advanced mobile, multiple user, and satellitebased solutions, that are nowadays among the most prevalent and widespread communication technologies. Such techniques may find adoption even in the aeronautical scenario, for achieving higher efficiency, and safer air transport systems, capable of meeting increasing demands. This paper provides a preliminary performance analysis of Direct Sequence Spread Spectrum signals, obtained through the use of innovative binary spreading sequences, the De Bruijn ones, in a scenario of large Doppler shift, and relative changing rate, as a result of the possibly high varying velocity of an aircraft, and worst-case condition of missing frequency offset estimation capability onboard. The results show that the use of binary De Bruijn sequences may improve signal recovery at the receiver, even in the presence of large distortions due to uncompensated Doppler effects.
This paper discusses the possible application of an innovative set of binary sequences, the De Bruijn ones, for spread spectrum applications, in which it may be useful to have a quite huge set of sequences to allocate different users, in order to avoid interference among them. The sequences are evaluated and compared to more traditional sets (Gold and Chaotic sequences) by means of the Periodic Ambiguity Function tool, and in a specific scenario related to the Entry, Descent and Landing stage of a Mars rover. The scenario is selected based on the critical Doppler phenomena it involves on signals transmitted from the lander to the Earth. Simulations show that De Bruijn sequences provide Doppler and Range performance comparable to those of the other sets, with the advantage of a much greater cardinality.
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