A backbone highway communications system using coaxial cable

The problem of providing the communication link for modern highway management and control is analyzed. A 100- mile span of highway is analyzed for typical voice and control function requirements plus closed circuit television monitoring capability. Based on this analysis, the number of channels and hence the bandwidth required to meet typical requirements is developed. It is proposed that a coaxial cable system can best provide the bandwidth and access flexibility that will be necessary for the many links required for effective highway management. A coaxial cable system as a transmission path is shown to be two dimensional in that it involves absolute signal levels as well as spectrum considerations. An analysis of distortion characteristics of state of the art coaxial cable systems is included to arrive at signal to noise plus distortion ratios versus cable length and amplifier gains. Typical cable costs, burial and tunneling labor costs are discussed to show economic practicality. Finally, two high-capacity cable systems are discussed to illustrate the communications capacity of coaxial cable systems.