Term of the Moment
antivirus program
Definition: communications
The transfer of data between locations. Communications may refer only to voice-related subjects such as PBXs, modems, call centers and the like or to any form of data transfer.
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 application and ending at the bottom with the plugs, sockets and electrical signals. See communications protocol and OSI model.
Analog vs. Digital Communications
Prior to the Internet, the world's largest communications system was the U.S. telephone network, a mix of analog and digital. It was originally analog and transmitted only voice frequencies. Today, the only analog part is the line between the customer's telephone and a digital conversion point (digital loop carrier) within a mile or so of the customer. In 2021, the FCC reported 36 million analog POTS lines in use, down from 122 million in 2010. U.S. homes and businesses began switching to digital "voice over IP" in the late 1990s (see VoIP and POTS).
Analog: Amplifiers Boost Noise
Analog systems are error prone because the electronic transmission of sound waves gets mixed together with 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 noise. By the time the person or modem received the signal at the other end, all the noise was amplified.
Digital: Repeaters Regenerate
In a digital telephone network, the transmitted voice is binary. Instead of amplifiers, repeaters analyze the incoming signal and regenerate a new outgoing signal, and any noise on the line is filtered out.
The First Analog Communications
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 application and ending at the bottom with the plugs, sockets and electrical signals. See communications protocol and OSI model.
Prior to the Internet, the world's largest communications system was the U.S. telephone network, a mix of analog and digital. It was originally analog and transmitted only voice frequencies. Today, the only analog part is the line between the customer's telephone and a digital conversion point (digital loop carrier) within a mile or so of the customer. In 2021, the FCC reported 36 million analog POTS lines in use, down from 122 million in 2010. U.S. homes and businesses began switching to digital "voice over IP" in the late 1990s (see VoIP and POTS).
Analog: Amplifiers Boost Noise
Analog systems are error prone because the electronic transmission of sound waves gets mixed together with 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 noise. By the time the person or modem received the signal at the other end, all the noise was amplified.
Digital: Repeaters Regenerate
In a digital telephone network, the transmitted voice is binary. Instead of amplifiers, repeaters analyze the incoming signal and regenerate a new outgoing signal, and any noise on the line is filtered out.
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.)