Short range wireless communication system
Ng, Ying Li.
Date of Issue2009
School of Electrical and Electronic Engineering
Centre for Integrated Circuits and Systems
A hearing impaired patient may not able to use the GSM phone or digital mobile phone together with his hearing aids as the interference due to the acoustical feedback becomes severe if the distance of the mobile phone and the hearing aids reduced. Therefore, it is necessary to develop a special device between the hearing aids and the mobile phone to reduce the interference and yet preserve the quality of sound. In this project, the developed device, i.e. neck-loop system is connected with Motorola i850, mobile phone or 2-way radio, for prototype testing purpose. An inductive coupled neck-loop is used not only to hold the adapter but also to induce audio signals in the hearing aids. In this system, the Push-to-talk (PTT) function in the handset is activated wireless by a designed remote control. This device enables the use of mobile phone together with the hearing aids effectively by reducing the interference between the mobile phone and the hearing aids significantly. The circuit was designed and its functionality was verified. The different functional block, e.g. PTT remote transmitter and neck-loop system adaptor were implemented in Printed Circuit Board (PCB) using Altium Designer Summer 8, a PCB designing tools, and the PCB board is fabricated. The components were assembled into the PCB and tested in order to verify and validate its functionality. At the end of this project, PTT function on handset can be remote at distance up to 1 meter. The devices can operate at 3V and CR2032 Lithium cell used for PTT remote transmitter and AAA dry-cell type battery used for Neck-loop system adaptor, those batteries are easily available in the market. Other than that, the amplifier used in this project can achieve up to 24dB voltage gain with small distortion. In conclusion, the neck-loop system design in this FYP is successful in term of its circuit design and functionality.
Final Year Project (FYP)
Nanyang Technological University