Bluetooth is a high end wireless technology designed for short range communications with high means of integrity. The application of Bluetooth technology for remote monitoring and control is an evolving concept in automation. However, in these applications, the controller which is controlled via Bluetooth technology or the sensor which transmits the sensed values via Bluetooth technology is application-specific. On the other hand, more productivity can be achieved by making the module general purpose, such that it can be used for wide range of applications. In fact, the general purpose concept can be applied to a selected set of devices with standard data interfaces, by making the system general purpose to the developer rather than the end user.In this work, a general purpose controlling module is designed with the capability of controlling and sensing up to five devices simultaneously. The communication between the controlling module and the remote server is done using Bluetooth technology. The server can communicate with many such modules simultaneously. The module can handle both analog and digital devices provided with suitable interfaces designed by the developer. Furthermore, an Application Programming Interface (API) is introduced to the developer for absorbing the benefits of the controller. A remote monitoring and controlling system was successfully developed using the proposed module and the system was deployed for an application of home automation with a selected set of electrical appliances.
Rain attenuation is the dominant propagation impairment at microwave frequencies, which varies for different countries/regions and essential to quantify correctly for satellite systems design. There was a consistent need to estimate and compare the practical rain fade margin with existing model estimations for Sri Lanka. This paper presents the rain rate and rain attenuation estimation for Ku band satellite signals by using established models as well as actual propagation measurements. Rainfall data over three years period is considered to estimate the highest rain rate distribution. Two satellite downlinks from Intelsat-12 & INSAT-4B are used for practical measurements and three rain attenuation models (ITU-R, DAH and Karasawa) are used to calculate the respective model estimations. It is found that the rain rate which exceeded 0.01% of cumulative time for an average year ( . ) as 105mm/h and resulted specific rain attenuation ( . ) is 2.8dB/km. Ka band rain attenuation for the same links is predicted using ITU-R frequency scaling method. Among the empirical models considered, DAH model gives overestimated results for the local context while the Karasawa model gives best-fit compliance with the measured path attenuation data.Index Terms -Rain attenuation, Ku band signal propagation, Yearly cumulative time of rain rate.
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