Modems History

It was in the 1950s that the first modems were being developed. There was a need to transmit data for North American air defense, so efforts were made to accomplish the goal of data transfer across the existing telephone wires. The air defense was using modems by the end of the 1950s, but the first commercial device was not available until 1962. It was called the Bell 103, by AT&T. This first modem allowed full-duplex transmission, and boasted data rates up to 300 bits per second. Shortly after the Bell 103, there came the Bell 212, which reached speeds of 1200 bits per second. It also employed a method of modulation called phase-shift keying (PSK). This was a step up from the frequency-shift keying (FSK) method that the Bell 103 employed.
Over the next fifteen years, the efforts were to make the modems transmit data at a higher rate. In order to accomplish this, the telephone system required some improvement. As it was, due to mutual interference of signals being attenuated at various rates through the system, there was smearing of data symbols. To compensate for this, equalizers needed to be applied to the telephone lines. The automatic adaptive equalizer was invented in 1965 at Bell Laboratories by Robert Lucky. While equalizers had been...

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