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Browse Prior Art Database

Digital Multiplexing Technique for Use With Fiber-Optic Technology

IP.com Disclosure Number: IPCOM000035407D
Original Publication Date: 1989-Jul-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 59K

Publishing Venue

IBM

Related People

Mosher, LG: AUTHOR [+2]

Abstract

This invention allows multiple Control Units (CUs) to share a single fiber-optic link to support all the devices normally attached by means of coax or twisted pair media. (Image Omitted)

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Digital Multiplexing Technique for Use With Fiber-Optic Technology

This invention allows multiple Control Units (CUs) to share a single fiber- optic link to support all the devices normally attached by means of coax or twisted pair media.

(Image Omitted)

A technique is described for multiplexing CU signals. By using hardware shift registers and First-In, First-Out Storage (FIFOS), it is able to drive and receive "off the shelf" fiber-optic emitter LEDs and P-I-N photodiodes. Unlike the analog- modulated circuitry and time division scanning schemes used with fiber optic transceivers, this technique uses a synchronous boost and then reassembly process.

Signals from the sending CUs or devices are fed to FIFOs where they are held until eight bits are available and then unloaded at a 2.3 mhz rate. The unloading continues until the specific FIFOs total message is complete. The FIFO is sixteen bits long to allow for oscillator tolerance variation between the message sending oscillator and the oscillator required in the fiber-optic redrive circuitry.

Fig. 1 shows very generally the logic flow from four CUs through the devices and similar return path. The number of CUs need not be limited to four; the practical limit will be determined by the availability concerns.

Fig. 2 shows how lower speed data streams are combined and boosted to a higher speed for transmission over the fiber link. The sync bits are used to re- orient the received data.

Fig. 3 shows how the FIFO outpu...