Back to the Basics: Communication Devices

Since today's communication technology can be confusing for many people, Genesis Global, Inc. wants to go back to the basics and take a brief look at the various types of communication channels available. This article addresses eight basic factors which affect data transmission: "transmission rate—frequency and bandwidth; line configurations—point-to-point versus multipoint; serial versus parallel transmission; direction of transmission—simplex, half-duplex, and full-duplex; transmission mode—asynchronous verses synchronous; packet switching; multiplexing; and protocols."

Transmission Rate—Frequency and Bandwidth

Frequency: Transmission rate (or speed) of information traveling through a channel can be effected by wave frequency. For example, twisted-pair telephone wires, coaxial cables, and fiber-optic cables are channels that send data at different speeds due to their different wave frequencies.

Bandwidth: Bandwidth is a channel that can send several speeds of frequency all at the same time. The more bandwidth there is, multiple frequencies of data can be transported at a faster speed. “The rate of speed of data through the channel is expressed in bits per second (bps), kilobits per second (Kbps), or megabits per second (Mbps).”

Line Configurations—Point-to-Point vs. Multipoint

Point-to-Point: “A point-to-point line directly connects the sending and receiving devices, such as a terminal with a central computer.” This method keeps data private and secure since data is transmitted from one device to another. A router connected to a PC is a simple example of a point-to-point connection.

Multipoint: “A multipoint line is a single line that connects several communications devices to one computer.” For instance, one line of coaxial cable can transmit data to three or more routers.

Serial vs. Parallel Transmission 

Serial: Bits of data travel through channels sequentially—one bit of data follows the next (as in the case of twisted-pair telephone lines). This is equivalent to cars moving down a one-lane road, one behind the other. 

Parallel Transmission: Bits of data “are transmitted through separate lines simultaneously. The arrangement resembles cars moving in separate lanes at the same speed on a multilane freeway.”

Direction of Transmission—Simplex, Half-Duplex, and Full-Duplex

Simplex: When two computers are in communication, data can flow through a channel in only one direction. For example, the traditional television only sends information out.

Half-Duplex: When two computers are in communication, data can flow in both directions. CB and marine radios can send and receive information, but not at the same time.
Full-Duplex: When two computers are in communication, data can flow in both directions at the same time as seen in telephone conversations.

Transmission Mode—Asynchronous vs. Synchronous 

Asynchronous: (also called start-stop transmission) In this mode, data is sent one byte (or character) at a time. "Each string of bits making up the byte is bracketed, or marked off, with special control bits. That is, a "start" bit represents the beginning of a character, and a "stop" bit represents its end."

Synchronous: (timed transmission) "Instead of using start and stop bits, synchronous transmission sends data in blocks. Start and stop bit patterns called sync bytes, are transmitted at the beginning and end of the blocks. These start and end bit patterns synchronize internal clocks in the sending and receiving devices so that they are in time with each other."

Packet Switching Messages: are broken or divided into packets when sent and pieced back together to form the original message within a network. This is not suitable for real-time video and voice transmission.

Multiplexing:  Multiplexing allows a single communications line to carry multiple signals at the same time. For example, trunk networks transmit thousands of telephone calls on a single line at the same time.

Protocols: Protocols are the rules that govern the exchange of information between software and/or hardware in a communications network.

To conclude, communication technology does not have to be confusing. As technology continues to evolve through time, so does our language. By expanding your technical vocabulary, you will be able to make more informed decisions on network hardware and network peripherals. Occasionally reviewing these basic terms, helps us to be more aware of the different data channels required for communication devices.

Give Genesis Global's Account Sales Managers a call at:
1-800-908-9665

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