People have communicated at a distance using fires, smoke, lanterns, flags, semaphores, etc. since ancient times, but the telegraph was the first electronic communication technology. Several inventors developed electronic telegraphs, but Samuel Morse’s hardware and code (using dots and dashes) caught on and became a commercial success. Computer-based data communication experiments began just after World War II, and they led to systems like MIT’s Project Whirlwind, which gathered and displayed telemetry data, and SAGE, an early warning system designed to detect Soviet bombers. The ARPANet, a general purpose network, followed SAGE. In the late 1980s, the US National Science Foundation created the NSFNet, an experimental network linking the ARPANet and several others – it was an internetwork. The NSFNetwork was the start of today’s Internet. 1
Improvement in the Internet illustrates communication technology progress. There are several important metrics for the quality of a communication link, but speed is basic.[*** Packet loss and data transfer rates are also common measures of communication quality. Researchers monitoring Internet performance have observed that between the spring of 1997 and fall of 2006 packet loss rates between North America and other regions of the world have typically fallen between 25 and 45 percent per year. Packet loss rates to developed nations are under 1 percent, but Africa has the highest loss rates and is falling further behind the other regions. They found comparable improvement when monitoring data transfer rates. (xx reference to SLAC site).] Speed is typically measured in bits per second – the number of ones and zeros that can be sent from one network node to another in a second. Initially the link speed between NSFNet nodes was 64 kilobits per second, but it was soon increased to 1.5 megabits per second then to 45 megabits per second. 2
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