Editing Scrambler (section)

=== Comparison of scramblers ===
Scramblers have certain drawbacks: 
* Both types may fail to generate random sequences under worst-case input conditions. 
* Multiplicative scramblers lead to error multiplication during descrambling (i.e. a single-bit error at the descrambler's input will result in ''w'' errors at its output, where ''w'' equals the number of the scrambler's feedback taps). 
* Additive scramblers must be reset by the frame sync; if this fails, massive error propagation will result, as a complete frame cannot be descrambled. (Alternatively if you know what was sent, the scrambler can be synchronized)
* The effective length of the random sequence of an additive scrambler is limited by the frame length, which is normally much shorter than the period of the PRBS. By adding frame numbers to the frame sync, it is possible to extend the length of the random sequence, by varying the random sequence in accordance with the frame number.