Abstract-Extended range telepresence aims at enabling a user to experience virtual or remote environments, taking his own body movements as an input to define walking speed and viewing direction. Therefore, localization and tracking of the user's pose (position and orientation) is necessary to perform a body-centered scene rendering. Visual and acoustic feedback is provided to the user by a head mounted display (HMD). To allow for free movement within the user environment, the tracking system is supposed to be user-wearable and entirely wireless. Consequently, a lightweight design is presented featuring small dimensions to fit into a conventional 13" laptop backpack, which satisfies the above stated demands for highly immersive extended range telepresence scenarios. Dedicated embedded hardware combined with off-the-shelf components is employed to form a robust, low-cost telepresence system that can be easily installed in any living room.

-Multilateration systems operate by determining distances between a signal transmitter and a number of receivers. In aerial surveillance, radio signals are emitted as Secondary Surveillance Radar (SSR) by the aircraft, representing the signal transmitter. A number of base stations (sensors) receive the signals at different times. Most common approaches use time difference of arrival (TDOA) measurements, calculated by subtracting receiving times of one receiver from another. As TDOAs require intersecting hyperboloids, which is considered a hard task, this paper follows a different approach, using raw receiving times. Thus, estimating the signal's emission time is required, captured as a common offset within an augmented version of the system state. This way, the multilateration problem is reduced to intersecting cones. Estimation of the aircraft's position based on a nonlinear measurement model and an underlying linear system model is achieved using a linear regression Kalman filter [1,2]. A decomposed computation of the filter step is introduced, allowing a more efficient calculation.

Abstract-Telepresence systems enable a user to experience virtual or distant environments by providing sensory feedback. Appropriate devices include head mounted displays (HMD) for visual perception, headphones for auditory response, or even haptic displays for tactile sensation and force feedback. While most common designs use dedicated input devices like joysticks or a space mouse, the approach followed in the present work takes the user's position and viewing direction as an input, as he walks freely in his local surroundings. This is achieved by using acoustic tracking, where the user's pose (position and orientation) is estimated on the basis of ranges measured between a set of ceiling-mounted loudspeakers and a microphone array fixed on the user's HMD. To allow for natural user motion, a wearable, fully wireless telepresence system is introduced. The increase in comfort compared to wired solutions is obvious, as the user's awareness of distracting cables is taken away during walking. Lightweight design and small dimensions contribute to ergonomics, as the whole assembly fits well into a small backpack.