Digital Communications Questions and Answers – Baseband Systems and Signal Transmission through Linear Systems

This set of Digital Communication Puzzles focuses on “Baseband System and Signal Transmission through Linear Systems”.

1. The point at which the output signal power has fallen to 0.707 of its peak value is called as _____
a) 3db point
b) Half power point
c) 3db & Half power point
d) None of the mentioned

Explanation: Half power point, also known as 3db point, is the frequency at which the output signal power falls to half of its highest value.

2. The ratio of the filter bandwidth at -60db and -6db amplitude response point is called as _____
a) Half point factor
b) Normalized factor
c) Shape factor
d) None of the mentioned

Explanation: The shape factor is a metric for how close a realisable filter is to an ideal filter. It’s the ratio between -60db and -6db amplitude points filter bandwidths.

3. As the order of the filter increases, the cost ______ and complexity ______
a) Increases, increases
b) Increases, decreases
c) Decreases, increases
d) Decreases, decreases

Explanation: According to the design of the filter as the order increases the complexity and cost of the filter also increases.

4. Which filter has maximum flatness?
a) Chebyshev filter
b) Butter-worth filter
c) High pass filter
d) Normalized filter

Explanation: The Butterworth filter is the closest approximation to an ideal filter and has the most pass-band flatness.

5. The measure of the width of the main lobe is called as ________
a) Null to null bandwidth
b) Half power bandwidth
c) Normalized bandwidth
d) Absolute bandwidth

Explanation: The maximum signal power is seen in the major lobe. The null to null bandwidth is a measurement of the main lobe’s diameter.

6. The process of data conversion along with formatting the data is called as ______
a) Formatting
b) Modulation
c) Source coding
d) Amplifying

Explanation: Source coding is the process of translating source information to a digital signal and formatting it.

7. Formatting is the process which includes
a) Pulse code modulation
b) Sampling
c) Quantization
d) All of the mentioned

Explanation: Formatting is the process of converting analogue data into digital signals utilising techniques such as sampling, pulse code modulation, and so on.

8. Analog information is converted to digital data using
a) Sampling
b) Quantization
c) Coding
d) All of the mentioned

Explanation: Textual information, analog information and digital information undergoes different processes before converting to binary or digital data. The method used for converting analog information are the given methods.

9. The process that transforms text into binary digits is called as _______
a) Binary coding
b) Data coding
c) Character coding
d) Sampling

Explanation: Character coding is the process of transforming textual data to binary digits, according to the definition.

10. For the number of bits, k=1 and number of symbols, M=2 the system is called as
a) Unary
b) Binary
c) Quarternary
d) None of the mentioned

Explanation: The number of symbols is M=2k for k number of bits. The system is known as binary coding when k=1 and M=2.

11. Perform the bit stream partitioning and find the 8-ary waveform for the word ‘THINK’.
a) 1204443464
b) 4643444021
c) 1240443464
d) none of the mentioned

Explanation: “THINK”
ASCII value: T-001010 ; H-000100; I-100100; N-011100; K-110100
8-ary symbols(split into 3 bits): 1 2 0 4 4 4 3 4 6 4.

12. Find the 32-ary waveform for the word ‘THINK’.
a) 514172520
b) 202517415
c) 541172520
d) None of the mentioned

Explanation: “THINK”
ASCII value: T-001010; H-000100; I-100100; N-011100; K-110100
32-ary symbols(split into 5 bits): 5 1 4 17 25 20.

13. Find the 8-ary waveform for the word ‘HAPPY’.
a) 4040020246
b) 0440020246
c) 6420200440
d) None of the mentioned

Explanation: “HAPPY”
ASCII value: H-000100; A-100000; P-000010; P-000010; Y-100110
8-ary symbols: 0 4 4 0 0 2 0 2 4 6.

14. Find the 32-ary waveform for the word ‘HAPPY’.
a) 280856
b) 658082
c) 288056
d) None of the mentioned

Explanation: “HAPPY”
ASCII value: H-000100; A-100000; P-000010; P-000010; Y-100110
32-ary symbols: 2 8 0 8 5 6.

15. What are the characteristics of an ideal transmission line?
a) Different amplitude
b) No distortion
c) Time delay
d) All of the mentioned

Explanation: The ideal transmission line’s output has a time delay and a different amplitude than the input, but it should not be distorted and should have the same form as the input.

A baseband channel, also known as a lowpass channel, is a communication channel that can transfer frequencies that are very close to zero. Frequency division multiplexing (FDM) permits a baseband telephone call to be carried on the same analogue telephone connection as one or more carrier-modulated calls. The ideal transmission line’s output has a time delay and a different amplitude than the input, but it should not be distorted and should have the same form as the input.