Question

(a) A teleprinter system operating at 200 baud, represents each alphanumeric character by a 5 bit codeword and each binary state by ± 10 V. If the line attenuation over a regenerator section is 46 dB and the rms noise voltage at the regenerator input is 17.2 mV, calculate the average character error rate per minute. Assume equal probability of each binary state and an optimum reference level for the decision comparator, stating its value in volts. Comment generally on the effect of each of the following on the error rate: (i) non-equal probability of state occurrence, (ii) inclusion of a parity bit in each codeword, (iii) use of two threshold levels with double the voltage swing at the teleprinter output, (iv) cascading n such regenerator sections. (b) Justify the following relationship for a single-error-correcting Hamming code, having R check bits and M data bits, with a Hamming distance of 3: M + R ? 2^R - 1 Outline a possible code table for such a Hamming code using 3 data bits and illustrate its error correction action by assuming an error in one of the received data bits.

          (a) A teleprinter system operating at 200 baud, represents each alphanumeric character by a 5 bit codeword and each binary state by ± 10 V. If the line attenuation over a regenerator section is 46 dB and the rms noise voltage at the regenerator input is 17.2 mV, calculate the average character error rate per minute. Assume equal probability of each binary state and an optimum reference level for the decision comparator, stating its value in volts.

Comment generally on the effect of each of the following on the error rate:

(i) non-equal probability of state occurrence,
(ii) inclusion of a parity bit in each codeword,
(iii) use of two threshold levels with double the voltage swing at the teleprinter output,
(iv) cascading n such regenerator sections.

(b) Justify the following relationship for a single-error-correcting Hamming code, having R check bits and M data bits, with a Hamming distance of 3:
M + R ? 2^R - 1

Outline a possible code table for such a Hamming code using 3 data bits and illustrate its error correction action by assuming an error in one of the received data bits.

(a) A teleprinter system operating at 200 baud, represents each alphanumeric character by a 5 bit codeword and each binary state by ± 10 V. If the line attenuation over a regenerator section is 46 dB and the rms noise voltage at the regenerator input is 17.2 mV, calculate the average character error rate per minute. Assume equal probability of each binary state and an optimum reference level for the decision comparator, stating its value in volts.

Comment generally on the effect of each of the following on the error rate:

(i) non-equal probability of state occurrence,
(ii) inclusion of a parity bit in each codeword,
(iii) use of two threshold levels with double the voltage swing at the teleprinter output,
(iv) cascading n such regenerator sections.

(b) Justify the following relationship for a single-error-correcting Hamming code, having R check bits and M data bits, with a Hamming distance of 3:
M + R ? 2^R - 1

Outline a possible code table for such a Hamming code using 3 data bits and illustrate its error correction action by assuming an error in one of the received data bits.

Added by Rebecca C.

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