cmv@cbnap.UUCP (01/13/84)
Mr. Nguyen I don't know if this is what you were interested in, but I thought it worthy enough to post on the net in any case. Reprinted with permission in part from: BELL LABS NEWS Jan 9, 1984 Vol.24 No.2 FIRST CSDC INSTALLATION A SUCCESS: OUR CUSTOMERS ARE SATISFIED Circuit Switched Digital Capability (CSDC), a system designed to make the most of conventional telephone lines, has been cut over for the first time. It is undergoing a technical trial at New Jersey Bell's Murray Hill switching center. Developed at AT&T Bell Laboratories, CSDC allows computers to communicate with each other at high speeds over the same lines used for regular phone calls. With it, customers can send nearly all types of signals - voice, graphics, and data - over conventional telephone lines. "CSDC is a giant step toward fully integrated voice and data communications networks that will bring new digital services right to the customer's doorstep," said Mark Mortensen, CSDC project manager at Bell Labs in HOMDEL. "At the touch of a button, a CSDC user can alternate between analog voice calls and digital data transmission to any other subscriber on a CSDC network at speeds as high as 56000 bits per second ..." ...Local telephone compaines expect to install CSDC equipment in over a dozen cities by the end of 1984. This equipment can be interconnected by long distance networks of various interexchange carriers. CSDC provides a common-user swithced network that transports information at 56 kilobits per second by transmitting digital, rather than analog signals... ...To use CSDC, a customer merely dials into the service with a five- digit access code, and then dials another user. Once a call is established, the connection can be alternated between voice and data transmission simply by pushing a button... ...they developed a time compression multiplexer, a device that alternately sends and receives bursts of data...Rather than sending signals in both directions at 56 Kb the multiplexers send signals at double that rate, but alternate between sending and receiving over 700 times a second... ..."As long as there is a circuit between the caller and the receiver that can carry digital signals - and there usually is - we can provide them with just about any new digital application that comes along in the forseeable future," Mortensen said. " ...here's lookin' at you kid " C. M. Votava, ...!cbosgd!noc!cmv ...!cbosgd!cbnap!cmv