Performance

When evaluating the suitability of a particular medium to a specific application, five factors should be kept in mind: cost, speed, attenuation, electromagnetic interference, and security.

• Cost. The cost of the materials, plus installation.

• Speed. The maximum number of bits per second that a medium can transmit reliably. Among other factors, speed varies with frequency (higher frequencies can transport more bits per second), with the physical size of the medium and/or transmission equipment, and with the conditioning of the conductor.

• Attenuation. The tendency of an electromagnetic signal to become weak or distorted over distance. During transmission, the signal's energy can become absorbed or dissipated by the medium itself. For example, a wire's resistance can leach energy from a signal and emit it in the form of heat.

• Electromagnetic interference (EMI). The susceptibility of the medium to external electromagnetic energy inadvertently introduced onto a link that interferes with the intelligibility of a signal. Familiar effects of EMI are static (audio) and snow (visual).

• Security. Protection against eavesdropping. How easy is it for an unauthorized device to listen in on the link? Some media, like broadcast radio and unshielded twisted-pair cable, are easily intercepted. Others, like fiber-optic cable, are more secure.

Table 5.3-1 compares the various media based on the qualities listed above.

Table 5.3-1 Transmission media performance

Medium

Cost

Speed

Attenuation

EMI

Security

UTP

Low

1-100 Mbit/s

High

High

Low

STP

Moderate

1-150 Mbit/s

High

Moderate

Low

Coax

Moderate

1 Mbit/s-1 Gbit/s

Moderate

Moderate

Low

Optical fiber

High

10 Mbit/s-2 Gbit/s

Low

Low

High

Radio

Moderate

1-10 Mbit/s

Low-high

High

Low

Microwave

High

1 Mbit/s-10 Gbit/s

Variable

High

Moderate

Satellite

High

1 Mbit/s-10 Gbit/s

Variable

High

Moderate

Cellular

High

9.6-19.2 kbit/s

Low

Moderate

Low

Body Language Magic

Body Language Magic

Most people don't often mean what they say. How to Efficiently Decode People's Inner Feelings and Emotions Through Their Body Movements, and How You Can Use This Knowledge to Succeed in Your Career, Relationships, and Personal Life! What I am about to tell you might shock you. Many people think that the most popular way of communicating with other people is through the mouth. But what they didn't know is that actual verbal communication accounts to only around 10 or even less of the overall means to convey a message.

Get My Free Ebook


Post a comment