The minimum step-size required for a Delta-Modulator operating at 32 k samples/sec to signal (here u(t) is the unit-step function) x(t) = 125t(u(t) - u(t - 1)) + (250 - 125t)(u(t - 1) - u(t - 2)) so that slope-overload is avoided, would be
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Which of the following use syndrome decoding?
A. Block codes
B. Line codes
C. Convolutional codes
D. Cyclic codes
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The advantage of differential PSK (DPSK) over coherent PSK is
A. DPSK requires less bandwidth compared coherent PSK
B. DPSK receiver design is simple compared to coherent PSK
C. DPSK Bit Error rate is lower than coherent PSK
D. For same bandwidth, DPSK bit rate is higher compared to coherent PSK
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In an ADM transmission system, the output signal amplitudes for 1's and 0's are
A. fixed and the repetition rate is also fixed
B. fixed but the repetition rate is also fixed
C. variable and the repetition rate is also variable
D. variable but the repetition rate is fixed
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For the modulated carrier in a quadrature amplitude shift keying (QASK) digital system:
A. The transmitted power is independent of data
B. Every signal is orthogonal to every other signal
C. No signal is orthogonal to any other signal
D. Some signals are orthogonal to some others
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A PAM signal can be detected by using
A. an ADC
B. an integrator
C. a band pass filter
D. a high pass filter
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How many bits are required to divide 10 V into 0.001 V intervals?
A. 14 bits
B. 20 bits
C. 1024 bits
D. 100 bits
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In a PCM system, if N is the number of levels and Z is the step size, then mean square quantization error is given by:
A. 12 NZ
B. 12 Z 2
C. 12 N Z 2
D. 12 N Z 2
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Consider the following:
A. 1 and 2 only
B. 2 and 3 only
C. 1 and 3 only
D. 1, 2 and 3
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In a digital communication system employing Frequency Shift Keying (FSK), the 0 and 1 bit are represented by sine waves of 10 kHz and 25 kHz respectively. These waveforms will be orthogonal for a bit interval of
A. 45 µsec
B. 200 µsec
C. 50 µsec
D. 250 µsec
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The probability of error of DPSK is . . . . . . . . than that of BPSK.
A. Higher
B. Lower
C. Same
D. Not predictable
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The peak-to-peak input to an 8-bit PCM coder is 2 Volts. The signal power-to-quantization noise power ratio (in dB) for an input of 0.5cos(ωm t) is
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Consider the signal x(t) shown in the figure. Let h(t) denote the impulse response of the filter matched to x (t), with h(t) being non-zero only in the interval 0 to 4 sec. The slope of h(t) in the interval 3 < t < 4 sec is
A. 2 1 sec − 1
B. − 1 sec − 1
C. − 2 1 sec − 1
D. 1 sec − 1
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The spectrum of BFSK may be viewed as the sum of
A. Two ASK spectra
B. Two PSK spectra
C. Two FSK spectra
D. Two QPSK
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Consider an analog signal sampled at a rate of 2 KHz and quantized into 128 levels. The time duration for each bit of the binary encoded
signal is:
A. 0.01
B. 0.035
C. 0.0714
D. 0.05
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Signal to noise ratio is highest in:
A. PWM
B. PPM
C. PAM
D. PPM and PWM
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A 6 MHz channel is used by digital signaling system utilizing four-level signals. The maximum possible transmission rate is
A. 6 M bauds/s
B. 18 M bauds/s
C. 9 M bauds/s
D. 12 M bauds/s
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A group of N stations shares a 56 kbps pure ALOHA channel. Each station outputs a 1000 bit frame on an average of once every 100 sec. What is the maximum value of N?
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