Digital Communication - Study Mode
[#61] Consider a binary digital communication system with equally likely 0's and 1's. When binary 0 is transmitted the detector input can lie between the levels -0.25V and +0.25V with equal probability: when binary 1 is transmitted, the voltage at the detector can have any value between 0 and 1 V with equal probability. If the detector has a threshold of 0.2 V (i.e., if the received signal is greater than 0.2 V, the bit is taken as 1), the average bit error probability is
Correct Answer
(A) 0.15
[#62] A source produces binary data at the rate of 10 kbps. The binary symbols are represented as shown in the figure. The source output is transmitted using two modulation schemes, namely Binary PSK (BPSK) and Quadrature PSK (QPSK). Let and B2 be the bandwidth requirements of BPSK and QPSK respectively. Assuming that the bandwidth of the above rectangular pulses is 10 kHz, B 1 and B 2 are
Correct Answer
(C) B 1 = 20 kHz, B 2 = 10 kHz
[#63] The modulation scheme commonly used for transmission from GSM mobile terminals is
Correct Answer
(D) Gaussian Minimum Shift Keying (GMSK)
[#64] Consider a Binary Symmetric Channel (BSC) with probability of error being p. To transmit a bit, say 1, we transmit a sequence of three 1 s. The receiver will interpret the received sequence to represent 1 if at least two bits are 1. The probability that the transmitted bit will be received in error is
Correct Answer
(A) p 3 + 3p 2 (1- p)
[#65] The signal to quantization noise ratio in an n-bit PCM system
Correct Answer
(C) Increasing with increasing value of 'n'