NetWorks: The World of Digital Communication

A vast science of technology underlies communication in our world today.  Most of the time, it works below the radar.  An extensive interlocked network of hardware and software makes it possible.  Networks: The World of Digital Communication at the Museum of Nature & Science opens up for you how it can happen. 

Timeline of communication

How do we find ourselves in a digital age, daily using devices we generally do not understand but which we count on to communicate and conduct our work around the globe?  The timeline graphically portrays the ascent of communication over millennia.

Binary language

The binary numeral system (base 2 numerals) represents numeric values using two symbols, typically 0 and 1. Owing to its relatively straightforward implementation in electronic circuitry, the binary system is used internally by virtually all modern computers. 
In 1937, Claude Shannon produced his master's thesis at MIT that implemented Boolean algebra and binary arithmetic using electronic relays and switches for the first time in history. Entitled A Symbolic Analysis of Relay and Switching Circuits, Shannon's thesis essentially founded practical digital circuit design. 

In November, 1937, George Stibitz, working at Bell Labs, completed a relay-based computer he dubbed the "Model K" (for "Kitchen", where he had assembled it), which calculated using binary addition. Bell Labs thus authorized a full research program in late 1938 with Stibitz at the helm. Their Complex Number Computer, completed January 8, 1940, was able to calculate complex numbers. In a demonstration to the American Mathematical Society conference at Dartmouth College on September 11, 1940, Stibitz was able to send the Complex Number Calculator remote commands over telephone lines by a teletype. It was the first computing machine ever used remotely over a phone line.

Electromagnetic spectrum

Radio frequency refers to that portion of the electromagnetic spectrum in which electromagnetic waves can be generated by alternating current fed to an antenna.

Internet

Every computer that is connected to the Internet is part of a network.  At work, you may be part of a local area network, but you most likely still connect to the Internet using an ISP that your company has contracted with. When you connect to your ISP, you become part of their network. The ISP may then connect to a larger network and become part of their network. The Internet is simply a network of networks.  Most large communications companies have their own dedicated backbones connecting various regions. In each region, the company has a Point of Presence (POP). The POP is a place for local users to access the company's network, often through a local phone number or dedicated line. There is no overall controlling network. Instead, there are several high-level networks connecting to each other through Network Access Points or NAPs.

E-mail

The first e-mail message was sent in 1971 by an engineer named Ray Tomlinson. Prior to this, you could only send messages to users on a single machine. Tomlinson's breakthrough was the ability to send messages to other machines on the Internet, using the @ sign to designate the receiving machine.

Cellular telephones

One of the most interesting things about a cell phone is that it is actually a radio, extremely sophisticated but a radio nonetheless. The telephone was invented by Alexander Graham Bell in 1876, and wireless communication can trace its roots to the invention of the radio by Nikolai Tesla in the 1880’s.  It was only natural that these two great technologies would eventually be combined.

Before cell phones, people who needed mobile-communications installed radio telephones in their cars. In the radio-telephone system, there was one central antenna tower in a city had a few channels available. The phone in the car required a powerful transmitter to connect with the central antenna, big enough to transmit 40 or 50 miles.  Because there was only one central antenna in an area, few people could simultaneously use their radio telephones; there were not enough channels.  The genius of the cellular system is the division of a city into small cells, allowing extensive frequency reuse across a city so that millions of people can use cell phones simultaneously.

Nortel LearnIt is an internet site to develop your technology communication skills.

Resources

Nortel LearnIt:  http://www.nortellearnit.org/

Media History Timeline Project: http://www.mediahistory.umn.edu/time/prehist.html

Spectrum Allocation chart (PDF)

National Telecommunications and Information Administration: http://www.ntia.doc.gov/