This paper shows the basic similarities among various data transmission techniques. It generalizes the concept of how the signal element serves as a unifying feature of various modulation schemes. The present approach permits an extension of the digital echo modulation technique, originally introduced by A. Croisier and J-M. Pierret, to cover most of the cases of digital data transmission. The practical application of digital echo modulation to the design of modems is discussed and examples of digitally implemented modem transmitters are given.
Note: The Institute of Electrical and Electronics Engineers, Incorporated is distributing this Article with permission of the International Business Machines Corporation (IBM) who is the exclusive owner. The recipient of this Article may not assign, sublicense, lease, rent or otherwise transfer, reproduce, prepare derivative works, publicly display or perform, or distribute the Article.