Chapter 3 ITM 301 Mid Term Notes - Chapter 3 ITM 301 Mid Term Notes Summary Notes Information can be transmitted via two methods analog or digital

Chapter 3 ITM 301 Mid Term Notes - Chapter 3 ITM 301 Mid...

This preview shows page 1 - 2 out of 8 pages.

Chapter 3 ITM 301 Mid Term Notes Summary Notes: - Information can be transmitted via two methods: analog or digital. Analog signals are continuous waves that result in variable and inexact transmission. Digital signals are based on electrical or light pulses that represent information encoded in binary form. - In half-duplex transmission, signals can travel in both directions over a medium but in only one direction at a time. When signals can travel in both directions over a medium simultaneously, the transmission is considered full-duplex. - A form of transmission that allows multiple signals to travel simultaneously over one medium is known as multiplexing. In multiplexing, the single medium is logically separated into multiple channels, or subchannels. - Throughput is the amount of data that the medium can transmit during a given period of time. Throughput is usually measured in bits per second and depends on the physical nature of the medium. - Baseband is a form of transmission in which digital signals are sent through direct current pulses applied to the wire. Baseband systems can transmit only one signal, or one channel, at a time. Broadband, on the other hand, uses modulated analog frequencies to transmit multiple signals over the same wire. -Noise is interference that distorts an analog or digital signal. It may be caused by electrical sources, such as power lines, fluorescent lights, copiers, and microwave ovens, or by broadcast signals. - Analog and digital signals both suffer attenuation, or loss of signal, as they travel farther from their sources. To compensate, analog signals are amplified, and digital signals are regenerated through repeaters. - Every network is susceptible to a delay between the transmission of a signal and its receipt. This delay is called latency. The length of the cable contributes to latency, as does the presence of any intervening connectivity device. - Coaxial cable consists of a central metal conducting core (often copper) surrounded by a plastic insulator, a braided metal shielding, and an outer plastic cover called the sheath. The conducting core carries the electromagnetic signal, and the shielding acts as both a protection against noise and a ground for the signal. The insulator layer protects the copper core from the metal shielding. The sheath protects the cable from physical damage. - Most networks no longer rely on coaxial cable; however, if you obtain Internet service from a cable company, the cable that enters your home will be a type of coax known as RG-6. - Twisted pair cable consists of color-coded pairs of insulated copper wires, each with a diameter of 0.4 to 0.8 mm, twisted around each other and encased in plastic coating. - STP (shielded twisted pair) cable consists of twisted-wire pairs that are not only individually insulated, but also surrounded by a shielding made of a metallic substance such as foil to reduce the effects of noise on the signal.
Image of page 1
Image of page 2

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture