communications

communications

In the electronic world, it is the transfer of data and information from one location to another. "Data communications" or "datacom" refers to digital transmission. "Telecommunications" or "telecom" refers to a mix of voice and data, both analog and digital. However, due to digital convergence, "telecommunications" implies "data communications."

"Networking" generally refers to a local area network (LAN), but it may refer to a wide area network (WAN), which is commonly called a telecom network.

The term "communications" may refer only to voice-related subjects such as PBXs, modems, call centers and the like. However, the word is also a common English word such as in the "Analog Vs. Digital Communications" headline below. Thus, "communications" is used specifically in some cases and generically in others.

The Protocol
The way data communications systems "talk to" each other is defined in a set of standards called "protocols." Protocols work in a hierarchy starting at the top with the user's program and ending at the bottom with the plugs, sockets and electrical signals. See communications protocol and OSI.

Analog Vs. Digital Communications
Prior to the Internet, the world's largest communications system was the telephone network, a mix of analog and digital lines. It used to be entirely analog and transmitted only voice frequencies, but is today almost entirely digital. The only analog part is the line between the telephone and a digital conversion point (digital loop carrier) within about a mile of the customer.

Amplifiers Boost the Noise
Analog systems are error prone because the electronic frequencies get mixed together with unwanted, nearby signals (noise). In long distance analog telephone networks, amplifiers were placed in the line every few miles to boost the signal, but they also boosted the noise. By the time the person or modem received the signal at the other end, it may have been impossible to decipher.

Repeaters Regenerate
In a digital network, only two (binary) distinct frequencies or voltages are transmitted. Instead of amplifiers, repeaters are used, which analyze the incoming signal and regenerate a new outgoing signal. Any noise on the line is filtered out at the next repeater. When data are made up of only two signals (0 and 1), they can be more easily distinguished from the garble. Digital is simple.

The First Analog Communications

In 1876, Alexander Graham Bell sent the first electronic communications over a wire when he said, "Mr. Watson. Come here! I want you!" (Image courtesy of AT&T.)