Equalization and Non Coherent Detection MCQ [Free PDF] – Objective Question Answer for Equalization and Non Coherent Detection Quiz

1. The range of amplitude difference gives the value of

A. Width
B. Distortion
C. Timing jitter
D. Noise margin

Answer: B

In the eye pattern, the amplitude difference gives the value of distortion caused by ISI.

 

2. As the eye opens, ISI _______

A. Increases
B. Decreases
C. Remains the same
D. None of the mentioned

Answer: B

As the eye closes, ISI increases, and as the eye opens ISI decreases.

 

3. Pseudo noise signal has _______ and _______ SNR for the same peak transmitted power.

A. Larger, smaller
B. Smaller, larger
C. Larger, larger
D. Smaller, smaller

Answer: C

A training pulse is applied to the equalizer and a corresponding impulse response is observed. Pseudo noise is preferred as the training pulse as it has a larger SNR value and larger average power value.

 

4. The index value n, in the transversal filter can be used as.

A. Time offset
B. Filter coefficient identifier
C. Time offset & Filter coefficient identifier
D. None of the mentioned

Answer: C

The index n can be used as both time offset and the filter coefficient identifier, which is the address in the filter.

 

5. The over-determined set of equations can be solved using

A. Zero forcing
B. Minimum mean square error
C. Zero forcing & Minimum mean square error
D. None of the mentioned

Answer: C

The matrix x in the transversal equalizer is non-square with dimensions 4N + 1 and 2N + 1. Such equations are called an over-determined set. This can be solved by two methods called as zero-forcing method and the minimum mean square error method.

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6. If the filter’s tap weight remains fixed during the transmission of data, then the equalization is called as

A. Preset equalization
B. Adaptive equalization
C. Fixed equalization
D. None of the mentioned

Answer: A

If the weight remains fixed during the transmission of data then the equalization is called preset equalization. It is a simple method that consists of setting the tap weight according to some average knowledge of the channel.

 

7. Equalization method which is done by tracking a slowly time-varying channel response is

A. Preset equalization
B. Adaptive equalization
C. Variable equalization
D. None of the mentioned

Answer: B

This method is implemented to perform tap weight adjustment periodically or continually. Equalization is done by tracking a slowly varying channel response.

 

8. Preamble is used for

A. Detect the start of transmission
B. To set the automatic gain control
C. To align internal clocks
D. All of the mentioned

Answer: D

The receiver uses a preamble for detecting the start of transmission, sets automatic gain control, and aligns internal clocks and local oscillators with the received signal.

 

9. The disadvantage of the preset equalizer is that

A. It doesn’t require initial training pulse
B. Time-varying channel degrades the performance of the system
C. All of the mentioned
D. None of the mentioned

Answer: B

The disadvantage of preset equalization is that it requires an initial training period that must be invoked at the start of any new transmission. Also, the time-varying channel can degrade system performance due to ISI, since the tap weights are fixed.

 

10. For AWGN, the noise variance is

A. N0
B. N0/2
C. 2N0
D. N0/4

Answer: B

The noise variance out of the correlator for AWGN is N0/2.

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