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forward
channel is continuous, contiguous series of
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blocks,
interleaved with sync. and control flags
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forward
synchronization word
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n |
marker
for FEC block boundaries and timing references
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n |
binary
value: 11101 00001 11000 00100 11001 01010 01111
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n |
each
group of five bits XOR-ed with one 5-bit busy/idle flag
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control
flags
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n |
busy/idle
status flag: signals status of reverse channel
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– |
channel
busy = 00000, channel idle = 11111
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n |
block
decode status flag: could received block be decoded
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(burst
errors and collision both prevent successful decoding)
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success
= 00000, failure = 11111
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– |
transfer
6 or 7 bits, but ignore extra bits (flag is one 5-bit word)
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