IoT-based sound-level control for audio amplifiers: mosques as a case study

<p><span>When using audio-amplifiers in the open, uneven distribution of sound makes people unpleasant because it is loud or unheared. This unfortunate situation arises because audio-amplifiers volumes are set according to the guess of sound technicians. Mosques, as an example, are distributed inside wide areas and fire Azan five times a day. Due to the relatively long distances between them, speed and direction of the wind impose setting sound levels prior to each Azan such that all the area is covered and the overlap is minimized. In this paper, we propose a system based on internet of things (IoT) model to control the sound level of each mosque in the community. An IoT device (one in a mosque) sets the level of sound fired by the audio-amplifier. To do that, a synchronized series of tones is fired from each node. Once a node hears these tones, the process of sound level control starts to indicate the distances to heared nodes. As the approximate distances between nodes are known, each node can calculate its suitable sound level. Results showed that the proposed system is effective in setting sound levels for mosques audio amplifiers.</span></p>

Design and Development of Non-Linearly Controlled Class-D Audio Amplifier

A systematic and simple approach to develop a 20 W audio frequency range switch mode amplifier is presented in this paper. A non-linear sliding mode (SM) technique-based low cost analog controller enables the realized amplifier to deliver highly linear and efficient operation throughout the audio frequency spectrum. The theoretical aspects and practical limitations in the design and realization of subsystems, such as the signal conditioning stage, power stage and sliding mode controller, are considered, while the viable solution is also stated and justified. The hardware realization scheme is also elaborated, based on which the laboratory prototype is fabricated. Hardware results with a 4 Ω resistive load are given on which the performance of the amplifier is evaluated. The total harmonic distortion (THD) below 1% and 73% efficiency at peak load make the amplifier well suited for high quality audio application.

Design and Development of Audio Data Transmission Using Visible Light Communication

Technological developments have opened up a new infrastructure in communication for transmitting audio data. This is evidenced by the large number of communication media, both wired and wireless. So that it raises new methods for sending audio data, one of which is using Visible Light Communication (VLC). VLC is a communication system for transmitting and receiving data using the visible light wave spectrum between 375 nm - 780 nm. In this research, audio data communication utilizes the brightness of the LED light. The transmitter and receiver use an LED component as a transducer which is then sent to the data processing circuit. From the data processing circuit then sent to the audio amplifier circuit. From the test results it can be shown that this system can transmit audio data. Based on the LED color test, Green produces the highest output voltage of 1.32 Volt. The angle limit that can be detected by the photo diode is at an angle of 70° with a measured voltage of 100mV and the resulting sound intensity of -32.541dB.