Control Building Fiber Preliminary Design Review December 5, 2001

IF Signal Path

CB Main Distribution Frame

Cable Type Required Plenum Cable is required in the building 30-Fiber tight buffer cables will be used

Control Building Main Distribution Frame

MDF Components

Termination Panel 876 fibers Provisions for 1200

Rack Mount EDFA

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Data Quality and Format Preliminary Design Review December 5, 2001

Bit Error Rates Continuous On-Line Monitoring –Hardware and software – Part of Receiver –MCB access Error Flag Sent to the Correlator –Single threshold error flag

Transmitter Power Automated Test –Measured at Each Laser Manual Test –Can be measured at the Mux output –Can be measured at the output of the De-Mux

Optical Power Continuous Optical Power will be measured –1% tap –The EDFA will measure the Optical Power –MCB access Total optical power is not a good indicator of BER

Eye Pattern Patch Panel –Manual measurements during reconfiguration Complete Diagnostic –Jitter –Q Factor –Noise Margin –Rise / Fall times

Test Patterns Generated at each Transmitter Nine Test Patterns –No Sync, alternating 1/0, all Ones, all Zeros MCB controlled

Frame Format

Frame Implementation

Divided Sync Word Required to Identify Correct 1/2 Sequence 10 Bits long, –6 bit identify Start-of-Frame –Barker Sequence - equal Ones versus Zeros Three Stage Synchronization Process

Three Stage Synchronization Stage 1 - Search bits for frame pattern Stage 2 – Monitor for “Correct” sync Stage 3 – If two “Bad” frames in a row or 2-out-of-8 fames are “Bad” Then Start Search Again

Scrambling Frame Synchronous Scrambling –Entire frame – except sync bits –Select pattern is modulo 2 added Pattern results in –Equal number of Ones/Zeros providing Balance ac content, sufficient transitions Minimize low frequency content

Timing Signals Metaframe Index Metaframe count 1 PPS 1 Pulse per 10 seconds

Data Valid Signal Initiated at the antenna –Toggle Switch –MCB controlled Passed to correlator

Check Sum - BER Each 19 bits Generate a check Sum Only odd # of errors per 19 bits Detected One error per frame is an Error Rate of about 10 -3

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