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Laser Shutdown And Bring Up Procedure

IP.com Disclosure Number: IPCOM000049696D
Original Publication Date: 1982-Jul-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Snedaker, MC: AUTHOR

Abstract

Optical fibers provide a very secure transmission media in that there is no radiated energy around the cable; thus the cable must be opened to intercept the signal.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 88% of the total text.

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Laser Shutdown And Bring Up Procedure

Optical fibers provide a very secure transmission media in that there is no radiated energy around the cable; thus the cable must be opened to intercept the signal.

An illegal interception can be detected in duplex systems using some form of continuous transmission code, such as one that sends idle characters whenever it is not sending data characters. The detection is accomplished by sensing that the receiver has gone to any steady state from full off to full on. Once "steady state" has been detected, the transmitter is signaled to shut down.

Safety regulations also may require shut down when "steady state" is detected, as eye damage can occur if someone looks too long at the end of a fiber being driven by a laser of sufficient power.

The problem then is to bring up the lasers once security has been restored or, if security is no problem, once the cable has been reconnected.

A method to do this is to wait one time increment after "steady state" detection before shutting down the transmitter. Then, after a wait of at least nine time increments, transmit for one time increment and shut down if "steady state" is still present.

The 10% transmission is safe as long as the time increment used is in the range of 10 milliseconds or less for low power lasers. For higher power the interval between transmits would be increased, thus reducing the "on" percentage.

By waiting one time increment after "steady state" detection before shutti...