ts. This is particularly true as the frequency increases. In other words, there was fairly severe amplitude distortion. Thus equalization became necessary. The mixing of two or more RF signals in the system caused intermodulation products and "beats" (harmonics), which degraded reception. When these TV signals carried modulation, cross-modulation (Xm) products degraded or impaired reception. Several small companies were formed to sell these "improved" television reception services. Some of the technicians working for these companies undertook ways of curing the ills of broadband amplifiers. These were coaxial cable systems, where a headend with a high tower received signals from several local television broadcasting stations, amplified the broadband signals, and distributed the results to CATV subscribers. A subscriber's TV set was connected to the distribution system, and the signal received looked just the same as if it were taken off the air with its own antenna. In fringe areas, signal quality, however, was much better than own-antenna quality. The key to everything was that no changes were required in the user's TV set. It was just an extension of her/his TV set antenna. This simple concept is illustrated in Figure 17.2. Note in Figure 17.2 that home A is in the shadow of a mountain ridge and receives a weakened diffracted signal off the ridge and a reflected signal off the lake. Here is the typical multipath scenario resulting in ghosts in A's TV screen. The picture is also snowy, meaning noisy, as a result of poor carrier-to-noise ratio. Home B extended the antenna height to be in line-of-sight of the TV transmitting antenna. Its antenna is of higher gain; thus it is more discriminating against unwanted reflected and diffracted signals. Home B has an excellent picture without ghosts. Home B shares its fine signal with home A by use of a 3-dB power split (P) and a length of coaxial cable. 17.2.2 Early System Layouts In Figure 17.1 we showed an early CATV distribution system (ca. 1968). Taps and cou- plers (