The recent proliferation of sensor-equipped smartphones has brought sensor networking to the general public in the form of mobile phone sensing.

Moreover, the energy sharing protocol can quantitatively share 113J energy with 96.82% accuracy in less than 2 seconds. Results indicate our charging and discharging control can effectively minimize the energy leaked away. We extensively evaluate our system under six real-world settings. To improve sharing efficiency subject to energy leakage, we develop an effective energy charging and discharging mechanism using an array of ultra-capacitors as the main component of an energy router. In a nutshell, energy routers exchange energy sharing control information using their data network while sharing energy freely among connected embedded sensor devices using their energy network. eShare supports the concept of energy sharing among multiple embedded sensor devices by providing designs for energy routers (i.e., energy storage and routing devices) and related energy access and network protocols. The ability to move energy around makes it feasible to build distributed energy storage systems that can robustly extend the lifetime of networked sensor systems. Our experiments on two common cell phone models have shown that we can achieve around one or two centimeters accuracy within a range of more than ten meters, despite a series of technical challenges in impl e- menting the idea. This technique cleverly avoids many sources of inaccuracy found in other typical time-of-arrival schemes, such as clock synchronization, non-real-time han- dling, software delays, etc. By counting the num- ber of samples between these two beeps and exchanging the time duration information with its peer, each device can de- rive the two-way time of flight of the beeps at the granularity of sound sampling rate. Each recording should contain two such beeps, one from its own speaker and the other from its peer.

To estimate the range between two devices, each will emit a specially-designed sound signal ('Beep') and collect a simultaneous recording from its microphone. It achieves high accuracy through a combination of three techniques: two-way sensing, self- recording, and sample counting. It is a pure software-based solution and uses only the most ba- sic set of commodity hardware - a speaker, a microphone, and some form of device-to-device communication - so that it is readily applicable to many low-cost sensor platforms and to most commercial-off-the-shelf mobile devices like cell phones and PDAs. It operates in a spontaneous, ad-hoc, and device-to-device context without leveraging any pre-planned infrastructure. We present the design, implementation, and evaluation of BeepBeep, a high-accuracy acoustic-based ranging system.

Mobius camera software for mac