Coding by Feedback Methods

This paper describes the basic feedback coder; that is, a device which converts an analog quantity such as a voltage into a digital quantity such as a binary number by the feedback method. The basic feedback coder consists of a decoding device or network together with an error amplifier and control circuits. The decoding network and its operation as a feedback element to produce a coding system are described in terms of a number system having any base, b. The particular case of a binary coder (base 2) is considered in detail. In addition, feedback coding systems employing a binary coded decimal number system are discussed. The advantages and disadvantages of the feedback method as compared to other coding methods are discussed. A method of nonlinear coding (or signal compression) directly in the coding process is presented.