Baseband Transmission MCQ || Baseband Transmission Questions and Answers

31. In which waveform logic 1 and logic 0 are represented by opposite one half-bit wide pulses?

  1. Unipolar RZ
  2. Bipolar RZ
  3. RZ-AMI
  4. Manchester coding

Answer.2. Bipolar RZ

Explanation:-

In Bipolar signal Binary 1’s arc is represented by alternately positive and negative values. The binary 0 is represented by a zero value. In bipolar return to zero waveform ones and zeroes are represented by opposite level pulses one half bit wide pulses.

 

32. In which waveform logic 1 is represented by equal amplitude alternating pulses?

  1. Unipolar RZ
  2. Bipolar RZ
  3. RZ-AMI
  4. Manchester coding

Answer.3. RZ-AMI

Explanation:-

The return-to-zero (RZ) waveforms consist of unipolar-RZ, bipolar-RZ, and RZ-AMI (alternate mark inversion). These codes find applications in baseband data transmission and in magnetic recording.

In RZ-AMI logic 1 is represented by equal amplitude alternating pulses and logic 0 is represented by the absence of a pulse.

 

33. Application of phase-encoded binary signals are

  1. Optical communication
  2. Magnetic recording
  3. Satellite telemetry
  4. All of the mentioned

Answer.4. All of the mentioned

Explanation:-

Different types of phase-encoded waveforms consist of
  • Biphase — mark or Manchester I code.
  • Biphase — level or Manchester II code.
  • Biphase — space 
  • Delay modulation (DM).
  • Miller coding

The phase-encoding schemes are used in magnetic recording systems and optical communications and in some satellite telemetry links.

 

34. For both PPM and PDM _______ is kept constant.

  1. Amplitude
  2. Time period
  3. Frequency
  4. Number of levels

Answer.1. Amplitude

Explanation:-

Pulse-density modulation, or PDM, is a form of modulation used to represent an analog signal with a binary signal.

Pulse-position modulation (PPM) is a form of signal modulation in which M message bits are encoded by transmitting a single pulse in one of the possible required time shifts.

In PPM waveform delaying or advancing of the pulse is done. In PDM the pulse width is varied. Thus in both cases, the amplitude is maintained constant.

 

35. In which waveform one is represented by half bit wide pulse positioned during the first half and zero is represented by half bit wide pulse positioned in the second half?

  1. Bi-p-L
  2. Bi-p-M
  3. Bi-p-S
  4. Delay modulation

Answer.1. Bi-p-L

Explanation:-

Bi-φ-L is popularly called Manchester coding. A one is represented by a half-bit wide pulse positioned during the first half of the bit interval whereas zero is represented by a half-bit wide pulse positioned during the second half of the bit interval.

 

36. In M-ary PPM waveform, modulation is effected by

  1. Delaying
  2. Advancing
  3. Delaying & Advancing
  4. None of the mentioned

Answer.3. Delaying & Advancing

Explanation:-

  • In the case of M-ary PPM waveforms, modulation is affected by delaying (or advancing) a pulse occurrence, by an amount that corresponds to the value of the information symbols.
  • In the case of M-ary PDM waveforms, modulation is affected by varying the pulse width by an amount that corresponds to the value of the symbols.
  • For both PPM and PDM, the pulse amplitude is held constant. Baseband modulation with pulses has analogous counterparts in the area of bandpass modulation.
  • PAM is similar to amplitude modulation, while PPM and PDM are similar to phase and frequency modulation respectively.

 

37. Which binary waveform uses three levels?

  1. Bipolar RZ
  2. RZ-AMI
  3. Bipolar RZ & RZ-AMI
  4. None of the mentioned

Answer.3. Bipolar RZ & RZ-AMI

Explanation:-

  • Many binary waveforms use three levels, instead of two, to encode the binary data. Bipolar RZ and RZ-AMI belong to this group. The group also contains for- mats called dicode and duobinary.
  • With dicode-NRZ, the one-to-zero or zero-to-one data transition changes the pulse polarity; without a data transition, the zero level is sent.
  • With dicode-RZ, the one-to-zero or zero-to-one transition produces | a half-duration polarity change; otherwise, a zero level is sent.

 

38. Which method should be implemented for reducing bandwidth?

  1. Multilevel codes
  2. Multilevel signaling
  3. PAM
  4. PDM

Answer.4. Multilevel signaling

Explanation:-

The transmission bandwidth required for binary digital waveforms is large. To reduce the bandwidth, a multilevel signaling method can be used.

Multilevel signaling is often used as a means of compressing the bandwidth required to transmit data at a given bit rate. As a result, the number of symbols that need to be transmitted is less than the number of bits (that is, the symbol rate is less than the bit rate), and hence the bandwidth is compressed.

 

39. Which waveform type has the feature of clocking?

  1. Manchester coding
  2. Bbi-p-M
  3. Delay modulation
  4. NRZ-L

Answer.1. Manchester coding

Explanation:-

In telecommunication and data storage, Manchester code (also known as phase encoding, or PE) is a line code in which the encoding of each data bit is either low then high, or high then low, for equal time. It is a self-clocking signal with no DC component.

In manchester coding transition occurs in the middle of every bit interval. Thus it has a feature of clocking.

 

40. Some of the M-ary waveforms are

  1. PAM
  2. PPM
  3. PDM
  4. All of the mentioned

Answer.4. All of the mentioned

Explanation:-

An M-ary transmission is a type of digital modulation where instead of transmitting one bit at a time, two or more bits are transmitted simultaneously. This type of transmission results in reduced channel bandwidth. However, sometimes, two or more quadrature carriers are used for modulation.

When we pulse modulate non-binary signals we get an M-ary waveform. Some of the examples of M-ary waveforms are PAM, PPM, PDM.

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