1. The method in which a small amount of controlled ISI is introduced into the data stream rather than trying to eliminate it completely is called as
A. Correlative coding
B. Duobinary signaling
C. Partial response signaling
D. All of the mentioned
Answer: D
The interference at the detector can be canceled out using these methods in which some controlled amount of ISI is introduced into the data stream.
2. From the digital filter we will get the output pulse as the _______ of the current and the previous pulse.
A. Summation
B. Difference
C. Product
D. Ratio
Answer: A
The digital filter incorporates one digit delay and thus it adds the incoming pulse with the value of the previous pulse.
3. In the duobinary signaling method, for M-ary transmission, the number of outputs obtained is
A. 2M
B. 2M+1
C. 2M-1
D. M2
Answer: C
In duobinary coding, the number of output obtained for M-ary transmission is 2M-1.
4. The method using which the error propagation in duobinary signaling can be avoided is
A. Filtering
B. Precoding
C. Postcoding
D. None of the mentioned
Answer: B
In the duobinary signaling method if one error occurs it repeats everywhere throughout the next steps. To avoid this precoding method can be used.
5. In the precoding technique, the binary sequence is _____ with the previous precoded bit.
A. And-ed
B. Or-ed
C. EXOR-ed
D. Added
Answer: C
To avoid error propagation precoding method is used. In this, each bit is encoded individually without having any effect due to its prior bit or decisions.
6. The duobinary filter, He (f) is called as
A. Sine filter
B. Cosine filter
C. Raised cosine filter
D. None of the mentioned
Answer: B
The transfer function is 2T cos(πfT) which is called a cosine filter.
7. The method which has greater bandwidth efficiency is called as
A. Duobinary signaling
B. Polybinary signaling
C. Correlative coding
D. All of the mentioned
Answer: B
If more than three levels are introduced in the duobinary signaling technique the bandwidth efficiency increases This method is called polybinary signaling.
8. In the polybinary signaling method the present bit of binary sequence is algebraically added with ______ number of previous bits.
A. j
B. 2j
C. j+2
D. j-2
Answer: D
In the polybinary signaling method, the present binary digit of the sequence is formed from the modulo-2 addition of the j-2 preceding digits of the sequence and the present digit.
9. The primary advantage of this method is
A. redistribution of spectral density
B. to favor low frequencies
C. redistribution of spectral density & favor of low frequencies
D. none of the mentioned
Answer: C
Each bit can be independently detected despite strong correlation and this provides redistribution of the spectral density and also favors low frequencies.
10. Source encoding procedure does
A. Sampling
B. Quantization
C. Compression
D. All of the mentioned
Answer: D
Source encoding includes a sampling of continuous-time signals, quantization of continuous-valued signals, and compression of those sources.
