Principles Digital Communication System & Computer Networks (Charles River Media Computer Engineering)

3.2 COAXIAL CABLE

Coaxial cable is used extensively for cable TV distribution, long-distance telephone trunks, and LANs. The cross-section of a coaxial cable used in an Ethernet local area network is shown in Figure 3.1.

Figure 3.1: Coaxial cable used in Ethernet LAN.

Coaxial cable can support a maximum data rate of 500Mbps for a distance of about 500 meters. Repeaters are required every 1 to 10 kilometers.

Coaxial cable is used in long distance telephone networks, local area networks, and cable TV distribution networks.

The speed of transmission in copper cable is 2.3 × 10⁸ meters/second. Note that this speed is less than the speed of light in a vacuum (3 × 10⁸ meters/second).

Based on the speed of transmission and the distance (length of the cable), the propagation delay can be calculated using the formula

Delay = distance/speed

For example, if the distance is 10 kilometers, the propagation delay is

Delay = 10,000/(2.3 × 10⁸) seconds = 43.48 microseconds.