Wideband Frequency Modulation Applications and Techniques

摘要

Frequency modulation (FM) is used extensively in audio communication and data transfer. When spectrum efficiency is important narrowband FM (NBFM) is used but when better signal quality is required wideband FM (WBFM) is used at the expense of greater spectrum usage. The term WBFM is used in applications where the modulation index is equal to or larger than 1. However, in this article, we are going to address applications and techniques for WBFM with modulation indexes much larger than that, going up to 100 and beyond. In such applications spectral efficiency is less important and sometimes large spectral spread is actually desired. The purpose of this article is to present some major applications in the commercial and defense markets as well as the common techniques of generating WBFM.