Transmission of Analog Video and Digital Signals Over Analog-Repeatered Coaxial Lines

The transmission of digital telephony or data, alone and together with analog video, over analog-repeatered coaxial-cable lines is discussed. Expressions for the total random noise power and the signal-to-noise ratio (SNR) are derived. These expressions include the effects of thermal noise and the intermodulation distortion due to nonlinearity in the analog repeater amplifiers. The dependence of the SNR on system parameters, particularly the signal level and the repeater spacing, for systems that carry digital telephony, video, or both, is discussed and its implications on system design are noted.