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The standard says "There is no requirement on the initial value for the scrambler. The scrambler is run continuously on all payload bits".

I'm curious how the scrambled data can be recovered. To my current knowledge, synchronization is needed to remove PR code from bit stream. Without aligning the PR code at Tx and Rx, how is descrambling possible?

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Hopefully this helps (emphasis mine):

Multiplicative scramblers (also known as feed-through) are called so because they perform a multiplication of the input signal by the scrambler's transfer function in Z-space. They are discrete linear time-invariant systems. A multiplicative scrambler is recursive, and a multiplicative descrambler is non-recursive. Unlike additive scramblers, multiplicative scramblers do not need the frame synchronization, that is why they are also called self-synchronizing. Multiplicative scrambler/descrambler is defined similarly by a polynomial, which is also a transfer function of the descrambler.

https://en.wikipedia.org/wiki/Scrambler#Multiplicative_(self-synchronizing)_scramblers

  • Thank you @Zac67. I had no idea with Multiplicative scramblers before this. A good point for me to know more. – fiedel Aug 14 '19 at 18:51

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