Scrambling is a technique used to rearrange digital data sequences to make them appear more random. It is used to prevent unauthorized access of data and avoid long runs of zeros and ones that could cause problems for receivers. There are two main types of scramblers: additive scramblers, which use XOR operations to scramble data, and multiplicative scramblers, which multiply data by a transfer function. Scrambling is widely implemented in communication systems like satellites, modems, and telephone networks to enhance security and reliability of data transmission.

1. LARAIB KIRAN
H1F18MSCT0020

2. CONTENT
• What is Scrambling
• Why scrambling is used?
• Types of scrambler
• Uses of Scrambler
• Drawbacks
• Conclusion

3. SCRAMBLING
• Scheme can principally provide processing applied to the
transmission rate signal in order to make the resulting binary
sequence appear more random
• It is rearrangement of data sequence
• 10010110 10101010

4. WHY SCRAMBLING IS USED?
• It prevent from unauthorized access of data
• 1100110011 01010101
• Time extraction:
• Manipulates data stream
• Long sequence of zero’s and one’s
• 11110000  problem at receiver side

5. SCRAMBLER
• Scrambler is a device that transposes or inverts signals
• It consist shift registers
• Descrambler:
An electronic device that decodes a scrambled transmission into a signal
that is intelligible to the recipient.

6. SCRAMBLING IS WIDELY USED IN
• satellite
• radio relay communications
• PSTN (Public Switched Telephone Network) modems
• Placed just before and after a FEC (Forward Error Correction)
coder
• Just before the modulation or line code

7. TYPES OF SCRAMBLER
• Additive scramblers
• Multiplicative scramblers

8. TYPES OF SCRAMBLERS
• Additive scramblers
• Additive scrambles transform the input data stream by applying a pseudo-
random binary sequence by modulo-two addition(XOR)
• Sometimes a pre-calculated PRBS stored in the ROM is used, but more often
it is generated by a linear-feedback shift register
• Multiplicative scramblers
• Multiplicative scramblers they perform a multiplication of the input signal by
the scrambler's transfer function.
• A multiplicative scrambler is recursive, and a multiplicative descrambler is
non-recursive.

9. DRAWBACKS:
• Both types may fail to generate random sequences under
worst-case input conditions.
• Multiplicative scramblers lead to error multiplication during
descrambling
• Additive scramblers must be reset by the frame sync if this
fails, massive error propagation will result, as a complete frame
cannot be descrambled.

10. CONCLUSION
• A scrambler & descrambler accepts information in intelligible
form and through intellectual transformation assure
• data quality
• fastest rate without any error
• current design is very efficient, more securable , low power and
lower area