In scrambling, a data stream is scrambled according to a specified mathematical polynomial. In principle, scrambling is performed by a pseudorandom generator of length 2expn-1 with n feedback stages. This technique is used to avoid uniform signal patterns and provides a more even distribution of signal energy over the entire frequency range. Scrambling prevents signal energy from being concentrated in a narrow frequency band with high amplitude, as would occur with long repetitive bit patterns such as the idle signal without scrambling.
Scrambling can improve the characteristics of non-code-transparent transmission schemes. Scramblers are used in modem technology, baseband technology and in the transmission of radio and television signals. Most V-series modems use the scrambling technique. In local area networks, this technique is used in transceivers.
- In smart cards, scrambling is the random assignment of buses. In this case, the different buses of the microcontroller can no longer be assigned in their function, since the address bus, the data bus and the control bus are mixed with each other. This mixing can vary from chip card to chip card.
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