A signal x(t) = 100cos(24π × 10<sup>3</sup>)t is ideally sampled with a sampling period of 50 psec and then passed through an ideal lowpass filter with cutoff frequency of 15 kHz. Which of the following frequencies is/are present at the filter output?

Which of the following statements are correct? 1. A lowpass filter passes low frequencies and stops high frequencies. 2. A highpass filter passes high frequencies and rejects low frequencies 3. A bandpass filter passes frequencies within a frequency band and attenuates frequencies outside the band. 4. A bandstop filter passes frequencies within the band and blocks/attenuates frequencies outside a frequency band.

A

1, 2 and 4 only

B

1, 3 and 4 only

C

2, 3 and 4 only

D

1, 2 and 3 only

A 1 kHz sinusoidal signal is ideally sampled at 1500 samples/sec and the sampled signal is passed through an ideal low-pass filter with cutoff frequency 800 Hz. The output signal has the frequency

A

Zero Hz

B

0.75 kHz

C

0.5 kHz

D

0.25 kHz

A signal containing only two frequency components (3 kHz and 6 kHz) is sampled at the rate of 8 kHz, and then passed through a low pass filter with a cut-off frequency of 8 kHz. The filter output

A

Is an undistorted version of the original signal

B

Contains only the 3 kHz component

C

Contains the 3 kHz component and a spurious component of 2 kHz

D

Contains both the components of the original signal and two spurious components of 2 kHz and 5 kHz

The signal $$\cos \left( {10\pi t + \frac{\pi }{4}} \right)$$ is ideally sampled at a sampling frequency of 15 Hz. The sampled signal is passed through a filter with impulse response $$\left( {\frac{{\sin \left( {\pi t} \right)}}{{\pi \tau }}} \right)\cos \left( {40\pi t - \frac{\pi }{2}} \right).$$ The filter output is

A

$$\frac{{15}}{2}\cos \left( {40\pi t - \frac{\pi }{4}} \right)$$

B

$$\frac{{15}}{2}\left( {\frac{{\sin \left( {\pi t} \right)}}{{\pi t}}} \right)\cos \left( {10\pi t + \frac{\pi }{4}} \right)$$

C

$$\frac{{15}}{2}\cos \left( {10\pi t - \frac{\pi }{4}} \right)$$

D

$$\frac{{15}}{2}\left( {\frac{{\sin \left( {\pi t} \right)}}{{\pi t}}} \right)\cos \left( {10\pi t - \frac{\pi }{2}} \right)$$

Let x(t) = 2cos(800πt) + cos(1400πt).x(t) is sampled with the rectangular pulse train shown in the figure. The only spectral components (in kHz) present in the sampled signal in the frequency range 2.5 kHz to 3.5 kHz are
Digital Communication mcq question image

Digital Communication mcq question image

A

2.7, 3.4

B

3.3, 3.6

C

2.6, 2.7, 3.3, 3.4, 3.6

D

2.7, 3.3

Assertion (A): Nyquist rate of sampling is the theoretical minimum sampling rate at which the signal can be sampled and still be reconstructed from its samples. Reason (R): When the Nyquist rate sampling is used, only an ideal low pass filter can be used to extract signal x(t) from sampled signal xs(t). Code:

A

Both (A) and (R) are true and (R) is the correct explanation of (A).

B

Both (A) and (R) are true, but (R) is not the correct explanation of (A)

C

(A) is true, but (R) is false.

D

(A) false, but (R) is true

Which one of the following is the correct sequence of various stages of operating cycle of a manufacturing company? 1. Raw material conversion period, work-in-progress conversion period, Finished goods conversion period, Receivables conversion period 2. Raw material conversion period, work-in-progress conversion period, Creditors payment period, Receivables conversion period 3. Creditor payment period. Raw material conversion period, Receivables conversion period, work-in- progress conversion period 4. Raw material conversion period, Finished goods conversion period, work-in- progress conversion period. Receivables conversion period

A

1

B

2

C

3

D

4

If, Fhp(u, v)=F(u, v) – Flp(u, v) and Flp(u, v) = Hlp(u, v)F(u, v), where F(u, v) is the image in frequency domain with Fhp(u, v) its highpass filtered version, Flp(u, v) its lowpass filtered component and Hlp(u, v) the transfer function of a lowpass filter. Then, unsharp masking can be implemented directly in frequency domain by using a filter. Which of the following is the required filter?

A

Hhp(u, v) = Hlp(u, v)

B

Hhp(u, v) = 1 + Hlp(u, v)

C

Hhp(u, v) = – Hlp(u, v)

D

Hhp(u, v) = 1 – Hlp(u, v)

Which of the two statements from the following statements are correct? (A) Sampling - related error is subsumed under the category non-sampling error. (B) Sampling error doesn't occur in multi-stage cluster sampling. (C) Inaccurate sampling frame and non-response are examples of sampling related error. (D) There is an inverse relation between heterogeneity of population and sampling error. Choose the correct option:

A

(A) and (C) only

B

(A) and (D) only

C

(B) and (D) only

D

(B) and (C) only

In an AM system receiver. the mixer translates the carrier frequency fc to a fixed intermediate frequency of 450 kHz. Given a broadcast signal of frequency 900 kHz. What is the corresponding image frequency when a superhetrodyne receiver is employed with local oscillator frequency greater than the broadcast signal frequency?

A

900 kHz

B

1800 kHz

C

800 kHz

D

1350 kHz

A signal x(t) = 100cos(24π × 10³)t is ideally sampled with a sampling period of 50 psec and then passed through an ideal lowpass filter with cutoff frequency of 15 kHz. Which of the following frequencies is/are present at the filter output?

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A signal x(t) = 100cos(24π × 103)t is ideally sampled with a sampling period of 50 psec and then passed through an ideal lowpass filter with cutoff frequency of 15 kHz. Which of the following frequencies is/are present at the filter output?

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A signal x(t) = 100cos(24π × 10³)t is ideally sampled with a sampling period of 50 psec and then passed through an ideal lowpass filter with cutoff frequency of 15 kHz. Which of the following frequencies is/are present at the filter output?