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:
Jul. 17, 1979
Filed:
May. 08, 1978
Robert Treiber, Centerport, NY (US);
International Telephone & Telegraph Corp., Nutley, NJ (US);
Abstract
A microprocessor controlled subscriber line circuit for interfacing analog telephone lines and trunks to a digital switching system is disclosed. All processing of incoming analog signals is accomplished by the line circuit, including the interface between the line and a digital switching matrix, measuring, monitoring, testing of the signals associated with the speech path. Additionally, the dc signal powering the carbon microphone on the handset is generated as well as ringing and other tones. Equalization and providing the two-wire to four-wire conversion with acceptable echo performance and minimized cross-office transmission loss are also accomplished. Analog-to-digital and digital-to-analog conversions are accomplished under microprocessor control as are the tone and power generation functions in a programmable power supply configuration utilizing pulse duration modulated feedback control in a programmable signal generator. The described subscriber circuit is particularly advantageous in that it is designed to maximize its implementation using solid state circuit techniques including large scale integration as opposed to conventional components and relays.