Tone Ringing and Pushbutton Calling

Abstract

Forward‐looking work on the telephone set has yielded attractive new solutions for the problem of signaling between the customer station and the central office. This work takes advantage of new electronic devices such as the silicon junction diode, the transistor and the ferrite coil. Two exploratory developments are described: a “tone ringer” and a “pushbutton caller,” both of which employ signals within the telephone speech band. Although usable separately, as justified by economic and other considerations in particular telephone systems, the developments have been conceived primarily as an integrated and moderately long range attack on the signaling problem, with special regard for the field of electronic switching.

Pushbutton Calling with a Two-Group Voice-Frequency Code

“…The first of these equations may be shown to be (1) where R 2 eff = R 2 + resistance of 6-7 windings of both coils + h;b (transistor grounded base input impedance); rb = turns ratio of base winding (8-9) to emitter winding (6-7); r, = turns ratio of tuned winding (1-5) to emitter winding (6-7); k = a factor less than unity (see below); L = nominal inductance of tuned winding (1-5) and Q, w, and a have the customary meanings, (nominal values).…”