Ray-tracing interpretation of wave normal directions of chorus emissions observed in the off-equatorial region of the outer magnetosphere

The previous direction finding measurements of chorus emissions with different spectral shapes (rising, falling, and constant tones) near the equator have indicated that those chorus emissions are generated around the equator with their wave normals being nearly aligned with the magnetic field in terms of the Cyclotron instability by energetic electrons. Their subsequent propagation in the outer magnetosphere is discussed in the present paper. First, the results of wave normal directions of chorus observed in the off-equatorial regions are reviewed; one from OGO 5 measurement and the other, our GEOS 1 result. These measurements are compared with the results of two-dimensional ray-tracing analyses for a realistic model of the outer magnetosphere. Finally, it is found that the subsequent propagation of chorus after the equatorial generation, is, on some occasions, ducted, and it is non-ducted on other occasions

2D communication sensor networks using single frequency for concurrent power supply and data transmission

Two-dimensional (2D) communication is a novel physical communication form that utilizes the surface as a communication medium to provide both data and power transmission service to the sensor devices placed on the surface's top. In previous works, we developed 2D communication systems that utilize separated channels for data and power transmission. Though this assignment of different channels can achieve strong network performance, the sensor devices must be equipped with two or more interfaces to simultaneously receive the power and data signals, which significantly complicates and enlarges those devices. Moreover, when a channel is used for the power supply,it continually monopolizes the wireless frequency resource. In this paper, we develop a novel 2D communication sensor system by using a single-carrier frequency for both power and data transmission, equipped with the wireless module for the two together in a compact body. To enable a sensor node that concurrently receives energy and data communication, we propose an enhancement scheme based on the IEEE802.15.4 MAC protocol standard. Through both computer simulation and actual measurement of the output power, we evaluate the performance of power supply and data transmission over the developed system