81. In DM, further the two integrators at encoding are replaced by one integrator placed before the comparator, and then such system is called?
A. System-delta modulation
B. sigma-delta modulation
C. Source-delta modulation
D. None of the mentioned
Answer: B
In DM, Furthermore, the two integrators at the encoder can be replaced by a single integrator placed before the comparator. This system is known as sigma-delta modulation (SDM).
82. What is the system function of the integrator that is modeled by the discrete time system?
A. H(z)=\(\frac{z^{-1}}{1-z^{-1}}\)
B. H(z)=\(\frac{z^{-1}}{1+z^{-1}}\)
C. H(z)=\(\frac{z^{z^1}}{1-z^1}\)
D. H(z)=\(\frac{z^{z^1}}{1+z^1}\)
Answer: A
The integrator is modeled by the discrete time system with system function
H(z)=\(\frac{z^{-1}}{1-z^{-1}}\)
83. What is the z-transform of sequence {dq(n)} i.e., Dq(z)= ?
A. \(H_s (z)X(z)- H_n (z)E(z)\)
B. \(H_s (z)X(z)+ H_n (z)E(z)\)
C. \(H_s (n)X(z)+ H_n (n)E(z)\)
D. \(H_n (z)X(z)- H_s (z)E(z)\)
Answer: B
The z-transform of sequence {dq(n)} i.e., Dq(z) IS
84. The performance of the SDM system is determined by the noise system function Hn(z), which has a magnitude of?
A. \(|H_n (z)|=2 |sin \frac{πF}{F_s}|\)
B. \(|H_n (z)|=4 |sin \frac{πF}{F_s}|\)
C. \(|H_n (z)|=3 |sin \frac{πF}{F_s}|\)
D. \(|H_n (z)|= |sin \frac{πF}{F_s}|\)
Answer: A
The performance of the SDM system is therefore determined by the noise system function H_(n)(z), which has a magnitude frequency response: \(|H_n (z)|=2 |sin \frac{πF}{F_s}|\).
85. The in-band quantization noise variance is given as?
A. \(\sigma_n^2=\int_{-B}^B |H_n (F)|^3 S_e (F)dF\)
B. \(\sigma_n^2=\int_{-B}^B |H_n (F)|^2 S_e (F)dF\)
C. \(\sigma_n^2=\int_{-B}^B |H_n (F)|^1 S_e (F)dF\)
D. None
Answer: B
The in-band quantization noise variance is given as:
\(\sigma_n^2=\int_{-B}^B |H_n (F)|^2 S_e (F)dF\)
where
\(S_e (F)=\frac{\sigma_e^2}{F_(s)}\) is the power spectral density of the quantization noise.
86. If the input analog signal is within the range of the quantizer, the quantization error eq (n) is bounded in magnitude i.e., |eq (n)| < Δ/2, and the resulting error is called?
A. Granular noise
B. Overload noise
C. Particulate noise
D. Heavy noise
Answer: A
In the statistical approach, we assume that the quantization error is random in nature. We model this error as noise that is added to the original (unquantizeD. signal.
If the input analog signal is within the range of the quantizer, the quantization error eq (n) is bounded in magnitude
i.e., |eq (n)| < Δ/2 and the resulting error is called Granular noise.
87. If the input analog signal falls outside the range of the quantizer (clipping), eq (n) becomes unbounded and results in _____________
A. Granular noise
B. Overload noise
C. Particulate noise
D. Heavy noise
Answer: B
In the statistical approach, we assume that the quantization error is random in nature. We model this error as noise that is added to the original (unquantizeD. signal. If the input analog signal falls outside the range of the quantizer (clipping), eq (n) becomes unbounded and results in overload noise.
88. In the mathematical model for the quantization error eq (n), to carry out the analysis, what are the assumptions made about the statistical properties of eq (n)?
A. The error eq (n) is uniformly distributed over the range — Δ/2 < eq (n) < Δ/2.
B. The error sequence is a stationary white noise sequence. In other words, the error eq (m) and the error eq (n) for m≠n are uncorrelated.
C. The error sequence {eq (n)} is uncorrelated with the signal sequence x(n).
D. All of the above
Answer: B
In the mathematical model for the quantization error eq (n). To carry out the analysis, the following are the assumptions made about the statistical properties of eq (n).
i. The error eq (n) is uniformly distributed over the range — Δ/2 < eq (n) < Δ/2.
ii. The error sequence is a stationary white noise sequence. In other words, the error eq (m)and the error eq (n) for m≠n are uncorrelated.
iii. The error sequence {eq (n)} is uncorrelated with the signal sequence x(n).
iv. The signal sequence x(n) is zero mean and stationary.
89. What is the abbreviation of SQNR?
A. Signal-to-Quantization Net Ratio
B. Signal-to-Quantization Noise Ratio
C. Signal-to-Quantization Noise Region
D. Signal-to-Quantization Net Region
Answer: B
The effect of the additive noise eq (n) on the desired signal can be quantified by evaluating the signal-to-quantization noise (power) ratio (SQNR).
90. What is the scale used for the measurement of SQNR?
A. DB
B. db
C. dB
D. All of the mentioned
Answer: C
The effect of the additive noise eq (n) on the desired signal can be quantified by evaluating the signal-to-quantization noise (power) ratio (SQNR), which can be expressed on a logarithmic scale (in decibels or dB.
