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SAMPLED 100BASE-TX NRZI EYE. -4. 0. 3. -5. -3. 4. -6. -1. 6. 2. 5. 7. -2. 1. -7. TIME (ns). DATA TRANSPORT MODULATOR/DEMODULATOR. line clock. /2. line data data. XOR. FF. data line data. sampled data line data. FF. Cable Station or Observatory ( transmit / receive ).
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SAMPLED 100BASE-TX NRZI EYE -4 0 3 -5 -3 4 -6 -1 6 2 5 7 -2 1 -7 TIME (ns) DATA TRANSPORT MODULATOR/DEMODULATOR line clock /2 line data data XOR FF data line data sampleddata line data FF Cable Station or Observatory (transmit/receive) DATA TRANSPORT MODULATOR WAVEFORMS data line clock sampled data half-rate clock line data (Demodulator waveforms are the same with some order reversal.) SSC-026 FORMAT and BIT-RATE INDEPENDENT COMMUNICATIONS over REGENERATED UNDERSEA FIBER OPTIC CABLE SYSTEMS PROJECT ALOHA Mark D. Tremblay, formerly at AT&T Labs & Tycom Labs (mdtremblay@optonline.net) Dr. Fred K. Duennebier, Department of Geology and Geophysics, University of Hawaii (fkd@hawaii.edu) DATA COMMUNICATIONS SYSTEM CONSIDERATIONS DATA TRANSPORT MODULATOR RESULTS • SEPARATE MAINTENANCE/COMM FUNCTIONS • LINE MAINTENANCE:USE NORMAL LINE SIGNAL • DATA COMMUNICATIONS:USE DATA MODULATOR SIGNAL • MEET ONLY MINIMUM LINE SIGNAL REQUIREMENTS • LINE FREQUENCY: USE NORMAL LINE CLOCK SIGNAL • 50% “1s” AND “0s”: DATA TRANSPORT MODULATOR • NO STRINGS OF “1s” and “0s”: DATA TRANSPORT MODULATOR • DATA RATE INDEPENDENCE (<10 TO > 100 MB/S) • NO DATA TRANSPORT MODULATOR OVERHEAD BITS: • RESULT: 50% CHANCE OF DATA SIGNAL BEING INVERTED • CONSEQUENCE: NONE; 100 MB/S ETHERNET NRZI CODING PRODUCES SIGNAL SENSE TRANSMISSION INDEPENDENCE ARBITRARY 25 MB/S DATA SIGNAL SHOWING 8.6% EYE CLOSURE DATA TRANSPORT MODULATION 125 MB/S DATA SIGNAL (100BASE-FX) SHOWING 43% EYE CLOSURE SUMMARY • APPLICABLE TO BOTH SL280 AND SL560 SYSTEMS(STATION ALOHA WILL ACTUALLY USE A SL560 REGENERATOR AT THE OBSERVATORY INTER-WORKING WITH A SL280 LINE) • COST-EFFECTIVE • SIMPLE OFF-THE-SHELF COMPONENTS • (2) 100 MB/S CHANNELS POSSIBLE OVER A SL280 SYSTEM • (4) 100 MB/S CHANNELS POSSIBLE OVER A SL560 SYSTEM • OTHER DIGITAL SYSTEMS APPLICATIONS POSSIBLE • CHANNEL RATE INDEPENDENT(<1 MB/S to > 125 MB/S) • INFORMATION INDEPENDENT (CLEAR CHANNEL) • LINE SUPERVISORY CAPABILITY MAINTAINED • (MANUAL CONNECTION OF NORMAL OR MODULATOR • LINE SIGNAL AS REQUIRED)