Abstract

The aim of the project is to develop a Miniaturised low power FM Transmitter to be used in specialised applications such as a hearing aid for a tour guiding system and room monitoring (such as a baby listening device). The overall module should be miniature to enable portability. Frequency modulation has several advantages over the system of amplitude modulation (AM) used in the alternate form of radio broadcasting. The most important of these advantages is that an FM system has greater freedom from interference and static. Various electrical disturbances, such as those caused by thunderstorms and car ignition systems, create amplitude modulated radio signals that are received as noise by AM receivers. A well-designed FM receiver is not sensitive to such disturbances when it is tuned to an FM signal of sufficient strength. Also, the signal-to-noise ratio in an FM system is much higher than that of an AM system. FM broadcasting stations can be operated in the very-high-frequency bands at which AM interference is frequently severe; commercial FM radio stations are assigned frequencies between 88 and 108 MHz and will be the intended frequency range of transmission.

The main report will reflect on 4 issues, background to frequency modulation, electronics component characteristics, basic transmitter building blocks and finally an analysis of the finished design as regards construction and performance.

Declaration

This report is presented in partial fulfilment of the requirements for the degree of Bachelor of Engineering.

It is entirely my own work and has not been submitted to any other University or higher education institution, or for any other academic award in this University. Where use has been made of the work of other people it has been fully acknowledged and fully referenced.

Francis Mc Swiggan, 24^th April 1998

Acknowledgements

I would very much like to gratefully extend my sincere thanks to all the people who gave generously their time, thanks one and all. Especially my supervisor Dr. Máirtín Ó Droma for the guidance he showed me right through every stage of the project, from initial conception to final design and construction.

Richard Conway for the loan of Electronic communication Techniques at the initial stage of the project, Elfed Lewis for kindly granting me access to his Pspice lab for initial simulation work. The technicians Jimmy Kelly, John Byrd, James Keane, John Maurice and many more of the lads in stores who helped me with a lot of the tedious leg work involved in giving life to a design and implementation project.

To the various chancers in my course. The "podger", "Richie of the hellen" and many more too numerous to mention, thanx Lads.

Dedication

To the person who supported me through 4 years of College Thanks Mam.