>There are a couple of cures for this. If the protocol is such
>that the packet preamble cannot legitimately appear in the body
>of a packet (some kind of out-of-band signal), you can watch
>for it at all times and abort decoding a bad packet if another
>preamble comes along.

I have a feeling that this is the sort of thing that HDLC/SDLC protocol does
by bit stuffing. The requirement is that within a valid message there can be
a maximum of 4 (IIRC) 0 or 1 in a row, and if that occurs then a bit of the
opposite state is "stuffed" into the message, irrespective of the state of
the next bit. However the preamble is deliberately set up to violate this
rule for the reasons given in the quote.

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