# tutorial3 - -3 Bit errors occur at random and independent...

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EE3015 Tutorial 3 (Data Communications) Review Questions y Describe what pulse coded modulation is. y What is the difference between multimode step-index fiber and multimode graded-index fiber? Problems 1. An audio digitizing utility in a PC samples an input signal at a rate of 44 kHz and 16 bits/sample. How big a file is required to record 20 seconds? 2. Suppose the information content of a packet is the bit pattern 1010101010101011 and an even parity scheme is being used. What would the value of the error checking field be for the case of a two-dimensional parity scheme? (Put the information bits into a 4 × 4 array.) 3. Suppose you have the following two data units: 1011001100110011 and 1110100101101001 . What is the corresponding checksum? Is it possible that a 1-bit error will go undetected? How about a 2-bit error? 4. Suppose a transmission channel operates at 3 Mbps and has a bit error rate of 10
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Unformatted text preview: -3 . Bit errors occur at random and independent of each other. Suppose that the following code is used. To transmit a 1, the codeword 111 is sent; to transmit a 0, the codeword 000 is sent. The receiver takes the three received bits and decides which bit was sent by taking the majority vote of the three bits. Find the probability that the receiver makes a decoding error. 5. Suppose that a parity check code has minimum Hamming distance d min . a) Show that if the distance between one codeword and a given bit string (of the same length) is less than d min / 2, the distance between any other codeword and the given bit string must exceed d min / 2. b) Show that if a decoder maps a given received string into a codeword at smallest distance from the string, all combinations of fewer than d min / 2 errors will be corrected....
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## This note was uploaded on 05/01/2011 for the course ELECTRICAL EE3015 taught by Professor Albertsun during the Spring '11 term at City University of Hong Kong.

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