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level: Level 1

Questions and Answers List

level questions: Level 1

Question	Answer
Analog Audio storage uses what type of media to store information?	Tapes
With constant use, tapes stretch out and exhibit what?	wow and flutter
What is the dynamic range of tapes?	70 dB
Ranges of signal amplitudes	Dynamic Range
It has a dynamic range of 100 - 120 dB (for soft music to still be heard and loud music will not saturate the amplifier)	Live orchestra
What is the meaning of CD?	Compact Disk
Creating pits and lands	Burning the CD
List all the CD Characteristics	diameter – 120 mm no. of tracks - 20,000 track width - 0.5 μm spacing between track - 1.6 μm total track length - 5300 m scan velocity - 1.2 m/s total playing time - 74 minutes
Microscopic bulge that stick out from the plastic	Pit
region between pits	land
The CD has no mechanical contact with the surface because of the usage of	Laser beam
There is a transmission from pit to land or vice-versa	binary 1
Bandwidth of a high-fidelity music	20 KHz
White noise is also known as	Dither noise
Why is there a need to add white noise?	White noise or Dither noise is added to mask any granular noise
It is used to encode parity or check symbols for error correction.	Cross Interleave Reed-Solomon Error Control Code (CIRC)
addition 4 8-bit parity symbols	P words
Converts 24-symbol sequence into a 32-symbol sequence	CIRC Module
adds an 8-bit symbol to each 32-symbol data block from the CIRC	Control-Word Module
takes each 8-bit symbol from the control word module and converts it to a 14-bit symbol	EFM (8 to 14 module)
choose 256 out of 16,384 possibilities to represent the data from the control word module	EFM Coding
Data is organized into blocks	Frame
decodes EFM signal and extract sync and control word information	Decoder
caused by air bubble or pit inaccuracies in the CD materials	Random Errors
caused by scratches, fingerprints and so forth	Burst errors
manifestation of errors during playback	click sound
employ check digits (change the errored bit to its opposite state)	correction
if bit is received with ambiguity and there is enough redundancy in the code	redundancy
conceal the incorrect value by interpolation between neighboring samples	concealment
get rid of the unreliable data (as long as muting does not exceed a few ms)	mute
encodes the characters using 4 to 1 bits instead of either 7 or 8 bits per character	Huffman coding
information bits are often repeated, ex. Long strings of spaces and carriage returns for spreadsheets	run-length encoding
to secure communication	Data Encryption
transformation of plaintext into cipher text	encryption
inverse of encryption process	Decryption
Set of transformations	Cipher
transformation paremeters	Keys
fixed blocks of plaintext are operated on in a combinational fashion	Block encryption
similar to convolutional encoding in that small segments of the plaintext are process	Stream Encryption
plaintext are cnverted into another set of symbols	Substitution
Permutation	rules where the characters are put in field block lengths and circularly shifter left or right
combination of P-box and S-box structure and is widely used	Product Cipher
single-key system developed by Diffie and Hellman (1979)used in banking, credit card operations, electronic fund transfers, etc.	Data Encryption Standard
in 1978 public key system based on the inherent difficulty of determining the prime factors of large numbers	Rivest-Shamir-Adleman System