A progressive code digital quantizer
Floyd Raasch · Transactions of the American Institute of Electrical Engineers Part I Communication and Electronics · 1953
The analog-to-digital converter described receives analog information obtainable from a graph reader or other analog source and gives a corresponding numerical indication. A progressive coding scheme is used to lessen chances of wrong readings. Several circuits are given for obtaining digital indication, the basic principle being based on comparing the analog voltage with the sum of a finite geometric series. A readout circuit is described for converting the coded digital indication to conventional decimal form for visual reading or for punching International Business Machines (IBM) cards.