|
Abstract:
|
Modulation in telecommunication systems, such as the frequency modulation used in audio broadcasting, has traditionally been performed using analog means. Digital circuits, however, provide a superior signal quality combined with the insensitivity to process and temperature variations, and aging. Thus, replacing the old analog components with their digital counterparts, while maintaining compliance with the existing devices, is often profitable. In this thesis, a digital frequency modulator architecture is presented. The modulator is intended to be used in a digital phase alternating line television broadcasting system, which is downward compatible with the existing analog solutions. The modulator is modelled using a hardware description language, and implemented on a field programmable gate array. The modulator architecture is area-optimised, taking into account the characteristics of the targeted gate array architecture. Digital frequency synthesizer, which is with respect to the area, delay, and modulation quality, the most important and critical component of the frequency modulator, is studied in detail. Various direct and indirect digital frequency modulator, is studied in detail. Various direct and indirect digital frequency synthesis methods and architectures are introduced and analyzed. The focus of the frequency synthesizer study is on the architecture and optimisation of the look-up table-based direct digital synthesizer, which was chosen for the modulator implementation. /Kir10 |