The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 10, 1983
Filed:
Feb. 26, 1981
Anes Sbuelz, Milan, IT;
Abstract
A tone generator for a telecommunication--especially telephone--system operating in the PAM/TDM mode comprises two complementary transistors with interconnected emitters joined to a 'hot' conductor of a two-wire transmission path forming part of a trunk line between two groups of subscribers, the collectors of these transistors being connected through respective series resistors to a positive and a negative terminal of a DC source. These collectors are further coupled via respective shunt condensers to the 'cold' conductor of the transmission path which is grounded through a low-ohmic further resistor. A local oscillator supplies a sinusoidal voltage wave through an operational amplifier to the interconnected bases of the two transistors whereby one or the other transistor conducts upon simultaneous closure, during a time slot assigned to a called subscriber, of a trunk switch at the near end and of a line switch at the far end of the transmission path enabling the resonant discharge of one of the previously charged shunt condensers into a remote line capacitor. Residual energy remaining stored on the parasitic capacitance of the two conductors is dissipated in a subsequent guard interval, upon the reopening of the two switches, as the partly discharged shunt condenser is recharged through the grounding resistor.