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Questions and Answers
What type of error occurs when a single bit is flipped in a data transmission?
What type of error occurs when a single bit is flipped in a data transmission?
Which of the following encoding schemes uses a 7-bit character encoding?
Which of the following encoding schemes uses a 7-bit character encoding?
What is the purpose of a cyclic redundancy check (CRC) in data transmission?
What is the purpose of a cyclic redundancy check (CRC) in data transmission?
Which of the following data compression techniques is a lossy compression method?
Which of the following data compression techniques is a lossy compression method?
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What is the primary difference between symmetric-key cryptography and asymmetric-key cryptography?
What is the primary difference between symmetric-key cryptography and asymmetric-key cryptography?
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What is the purpose of a hash function in cryptography?
What is the purpose of a hash function in cryptography?
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Which of the following encoding schemes is a block-based encoding scheme?
Which of the following encoding schemes is a block-based encoding scheme?
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What is the primary purpose of a parity bit in data transmission?
What is the primary purpose of a parity bit in data transmission?
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Which of the following compression techniques is a dictionary-based compression method?
Which of the following compression techniques is a dictionary-based compression method?
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What is the primary purpose of a checksum in data transmission?
What is the primary purpose of a checksum in data transmission?
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Study Notes
Error Correction
-
Types of errors:
- Bit-level errors: single-bit flip
- Burst errors: multiple consecutive bits affected
-
Error correction techniques:
- Parity bits: single-bit parity (odd/even) and two-dimensional parity
- Checksums: calculate and compare with received data
- Cyclic redundancy checks (CRCs): polynomial-based error detection
- Hamming codes: single-error correction and double-error detection
- Reed-Solomon codes: block-based error correction
Binary Representation
-
Binary number system:
- Base 2, using only 0s and 1s
- Can represent integers, fractions, and characters
-
Binary encoding:
- ASCII (American Standard Code for Information Interchange): 7-bit character encoding
- Unicode: 16-bit and 32-bit character encoding
- Binary-coded decimal (BCD): 4-bit encoding for decimal numbers
Encoding Schemes
-
Line encoding:
- Unipolar: single voltage level
- Bipolar: two voltage levels (positive and negative)
- Manchester: encoding with clock signal
-
Block encoding:
- Huffman coding: variable-length prefix codes
- Lempel-Ziv-Welch (LZW) coding: dictionary-based compression
- Run-length encoding (RLE): repeat-count encoding
Data Compression
-
Lossless compression:
- Huffman coding
- LZW coding
- RLE
- Arithmetic coding
-
Lossy compression:
- Discrete cosine transform (DCT): image and video compression
- Psychoacoustic models: audio compression
- Fractal compression: image and video compression
Cryptography
-
Types of cryptography:
- Symmetric-key cryptography: same key for encryption and decryption
- Asymmetric-key cryptography: public and private keys
-
Ciphers:
- Substitution ciphers: character substitution
- Transposition ciphers: character rearrangement
- Block ciphers: encrypting data in blocks
-
Hash functions:
- SHA (Secure Hash Algorithm): one-way encryption
- MD5 (Message-Digest Algorithm 5): one-way encryption
Error Correction
- Bit-level errors occur when a single bit is flipped
- Burst errors affect multiple consecutive bits
- Parity bits can detect single-bit errors using odd or even parity
- Checksums are calculated and compared with received data to detect errors
- Cyclic redundancy checks (CRCs) use polynomials to detect errors
- Hamming codes can correct single-bit errors and detect double-bit errors
- Reed-Solomon codes correct errors in blocks of data
Binary Representation
- Binary number system is base 2, using only 0s and 1s
- Binary can represent integers, fractions, and characters
- ASCII is a 7-bit character encoding standard
- Unicode uses 16-bit and 32-bit character encoding
- Binary-coded decimal (BCD) uses 4-bit encoding for decimal numbers
Encoding Schemes
- Unipolar line encoding uses a single voltage level
- Bipolar line encoding uses two voltage levels (positive and negative)
- Manchester encoding combines data with a clock signal
- Huffman coding uses variable-length prefix codes
- Lempel-Ziv-Welch (LZW) coding uses dictionary-based compression
- Run-length encoding (RLE) uses repeat-count encoding
Data Compression
- Lossless compression methods include Huffman coding, LZW coding, RLE, and arithmetic coding
- Lossy compression methods include discrete cosine transform (DCT), psychoacoustic models, and fractal compression
- Discrete cosine transform (DCT) is used for image and video compression
- Psychoacoustic models are used for audio compression
- Fractal compression is used for image and video compression
Cryptography
- Symmetric-key cryptography uses the same key for encryption and decryption
- Asymmetric-key cryptography uses public and private keys
- Substitution ciphers substitute characters
- Transposition ciphers rearrange characters
- Block ciphers encrypt data in blocks
- SHA (Secure Hash Algorithm) is a one-way encryption hash function
- MD5 (Message-Digest Algorithm 5) is a one-way encryption hash function
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Description
Learn about different types of errors and techniques used to correct them, including parity bits, checksums, cyclic redundancy checks, Hamming codes, and Reed-Solomon codes.
