CHAPTER 2 BASIC CABLE TV BACKGROUND: MODULATION SIGNAL FORMATS AND COAXIAL CABLE SYSTEMS

As we learned in chapter 1, HFC networks have evolved from traditionally broadcasting only multichannel analog video signals to a two-way mixture of analog and digital signals carrying both digital video and high-speed data. This chapter provides the basic technical background of cable TV systems carrying analog and digital video signals. Section 2.1 will explain the most commonly used analog video modulation formats, while Section 2.2 will discuss the different digital video and audio signal standards. The primary cable TV frequency plans that are used in the U.S. are reviewed in Section 2.3. In Section 2.4, the basic characteristics of multichannel coaxial systems are reviewed in terms of the properties of their components such as coaxial cables, taps, and RF amplifiers. The different degradation mechanisms over multichannel coaxial cable plants such as second- and third-order nonlinear distortions, multipath micro-reflections or echoes, group delay, and AM hum modulation are reviewed in Section 2.5. The last section will discuss the sources of upstream noise, including ingress noise, and their impact on the return-path transmission over cable TV networks. 2.1 Analog Modulated Video Signal Format