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A separated synchronizing scrambler/descrambler pair that removes the
possibility of catastrophic error due to improper transmission of initial
condition information without disrupting the OFDM modulation scheme of a
system that includes error-correction coding circuitry and replay
variation. A transmitting device within the pair includes a first and a
second data scrambler wherein the first data scrambler couples to receive
the incoming data stream and filters the incoming data stream to provide
a first filtered signal using a key signal. The second data scrambler,
having an initial condition, couples to receive the first filtered signal
and converts it into a scrambled signal using a scrambling seed. The
second data scrambler comprises a random series generator for generating
the scrambling seed to convert the first filtered signal into a scrambled
signal. The scrambled signal is transmitted to the receiving device. A
receiving device within the pair includes a first and a second data
descrambler coupled together. The first data descrambler, having an
initial condition equivalent to that of the second data scrambler,
couples to receive the transmitted scrambled input data stream to convert
it into a descrambled signal using a descrambling seed equivalent to the
scrambling seed. The first data descrambler includes a random series
generator for generating the descrambling seed. The second data
descrambler couples to receive the descrambled signal and filters it to
provide a filtered descrambled signal using a feedforward filter and a
key signal. The feedforward filter is structured similar to the feedback
filter.
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> Information distribution system, terminal apparatus, information center, recording medium, and information distribution method
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~ 00353
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