Identification of line circuits of an automatic switching system by line identification potential marking

摘要

713,703. Automatic exchange systems. STAATSBEDRIJF DER POSTERIJEN TELEGRAFIE EN TELEFONIE. May 8, 1952 [May 19, 1951], No. 11703/52. Class 40 (4) Corresponding test outlets of line finders OZ and final selectors EK are interconnected by a star or equivalent delta network of resistors R1 R2, R3, which are connected to a common potential VI of -60 volts and are so chosen that individual line finder and final selector outlets exhibit characteristic identification potentials in the ranges -32 to -60 volts and -28 to 0 volts respectively when the outlets are tested. The identity of line finder outlets is determined by a register (not shown) which tests the potential over a resistor R5 and busies the calling outlet by closing contact b. The corresponding final selector outlet then exhibits the correct identification potential between -28 to 0 volts instead of V1, and indicate a busy condition as well as permitting identification of the outlet by a register. Free final selectors initially have a potential V1, and the correct identification potential does not appear until a resistor R4 is connected in series by the register. A resistor of the same value. as R4 is connected to the outlet for the duration of the call to maintain a busy condition. Specification 647,073 is referred to.