MCQOPTIONS
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MCQOPTIONS
This section includes 21 Mcqs, each offering curated multiple-choice questions to sharpen your Electronics & Communication Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Number of bits per symbol in a 16 QAM is |
| A. | 4 |
| B. | 16 |
| C. | 8 |
| D. | 32 |
| Answer» B. 16 | |
| 2. |
In 512 QAM, the number of signal vectors of the signal constellation is: |
| A. | 820 |
| B. | 144 |
| C. | 512 |
| D. | 128 |
| Answer» D. 128 | |
| 3. |
Quadrature multiplexing is |
| A. | same as FDM |
| B. | same as TDM |
| C. | combination of FDM and TDM |
| D. | scheme where same carrier frequency is used for two different signals. |
| Answer» E. | |
| 4. |
In the modulation system, the energy per bit-to-noise power density ratio \(\frac{{{E_b}}}{{{N_o}}}\) is(1) \(\frac{C}{N} \times \frac{{{f_b}}}{B}\)(2) \(\frac{N}{C} \times \frac{B}{{{f_b}}}\)(3) \(\frac{C}{N} \times \frac{B}{{{f_b}}}\)(4) \(\frac{N}{C} \times \frac{{{f_b}}}{B}\)Where:N = Noise power of thermal (W)B = Bandwidth (Hz)C = Carrier power (W) fb = Bit rate (bps) |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» D. 4 | |
| 5. |
Quadrature Amplitude Modulation (QAM) is a combination of: |
| A. | ASK and FSK |
| B. | ASK and PSK |
| C. | FSK and PSK |
| D. | QPSK and FSK |
| Answer» C. FSK and PSK | |
| 6. |
ASK, PSK, FSK, and QAM are the examples of: |
| A. | Digital communication |
| B. | Analogue communication |
| C. | Ionosphere communication |
| D. | RF communication |
| Answer» B. Analogue communication | |
| 7. |
If carrier modulated by a digital bit stream had one of the possible phases of 0, 90, 180 and 270 degrees, then the modulation is called |
| A. | BPSK |
| B. | QPSK |
| C. | QAM |
| D. | MSK |
| Answer» C. QAM | |
| 8. |
An analog signal has a bit rate of 8000 bps and a baud rate of 1000 baud. The data elements carried by each signal and signal elements needed are respectively: |
| A. | 8 and 256 |
| B. | 4 and 16 |
| C. | 2 and 4 |
| D. | 7 and 128 |
| Answer» B. 4 and 16 | |
| 9. |
In a ASK system, the amplitude of the carrier signal is 10V and the binary to be transmitted is {1, 0, 1, 1, 1, 1, 0, 0, …}. The amplitude of the output will be: |
| A. | {± 5V, 0, ± 5V, ± 5 V, ± 5V, ± 5V, 0, 0,…} |
| B. | {0, ± 10V, 0, 0, 0, 0, ± 10 V, ± 10 V, …} |
| C. | {± 10 V, 0, ± 10 V, ± 10 V, ± 10 V, ± 10 V, 0, 0, …} |
| D. | {± 1 V, 0, ± 1 V, ± 1 V, ± 1V, ± 1V, 0, 0,…} |
| Answer» D. {± 1 V, 0, ± 1 V, ± 1 V, ± 1V, ± 1V, 0, 0,…} | |
| 10. |
For a total transmit power (Pt) of 1000 W and for a transmission rate of 50 Mbps, the energy per bit (Eb) will be |
| A. | 10 μJ |
| B. | 20 μJ |
| C. | 30 μJ |
| D. | 40 μJ |
| Answer» C. 30 μJ | |
| 11. |
For an 8-PSK system, operating with an information bit rate of 24 kbps, the baud rate will be |
| A. | 16,000 |
| B. | 12,000 |
| C. | 8,000 |
| D. | 6,000 |
| Answer» D. 6,000 | |
| 12. |
A binary data sequence 11001110 is applied to 16-ary PSK modulator system for transmission. The bit duration is 1 μ sec. The transmission bandwidth of 160-ary PSK is |
| A. | 1 MHz |
| B. | 0.67 MHz |
| C. | 0.5 MHz |
| D. | 0.37 MHz |
| Answer» D. 0.37 MHz | |
| 13. |
Match the following Lists:List-I List-II(a) ASK(i) Multiplier and an integrator(b) Matched filter(ii) Maximizes SNR at the output(c) PSK(iii) Digital to digital encoding(d) Correlation receiver(iv) Maximum probability of error Correct code is:Code: |
| A. | a-iii, b-ii, c-i, d-iv |
| B. | a-iv, b-iii, c-ii, d-i |
| C. | a-ii, b-iv, c-iii, d-i |
| D. | a-iv, b-ii, c-iii, d-i |
| Answer» E. | |
| 14. |
In FSK, the carrier frequency is switched between ______ extremes. |
| A. | 3 |
| B. | 6 |
| C. | 2 |
| D. | 4 |
| Answer» D. 4 | |
| 15. |
If bandwidth is of primary concern, which one of the following scheme is generally not considered? |
| A. | PSK |
| B. | ASK |
| C. | DPSK |
| D. | FSK |
| Answer» E. | |
| 16. |
8 Channel multiplex system has 5 kHz BW speech channels of the analog voltage range 0 to +2V. For 5 mV resolution, the minimum number of bits per sample in each channel and total BW of the system are _____ and _____ respectively. |
| A. | 9 and 360 KHz |
| B. | 9 and 720 KHz |
| C. | 9 and 40 KHz |
| D. | 10 and 40 KHz |
| Answer» C. 9 and 40 KHz | |
| 17. |
A coherent binary phase shift keyed (BPSK) transmitter operates at a bit rate of 20 Mbps. For a probability of error P(e) of 10–4, the ratio \(\frac{C}{N} = 8.8~dB\), the minimum theoretical \(\frac{{{E_b}}}{{{N_0}}}\) ratio for a receiver bandwidth equal to the minimum double-sided Nyquist bandwidth will be |
| A. | 4.8 dB |
| B. | 6.4 dB |
| C. | 8.8 dB |
| D. | 10.4 dB |
| Answer» D. 10.4 dB | |
| 18. |
If the bit rate for an ASK signal is 800 bps, the baud rate is: |
| A. | 1600 baud |
| B. | 400 baud |
| C. | 600 baud |
| D. | 800 baud |
| Answer» E. | |
| 19. |
In QPSK modulation scheme, to resolve the phase ambiguities, one should use |
| A. | staggered QPSK modulation scheme |
| B. | differential encoding. |
| C. | filtering. |
| D. | nothing needed to be done because QPSK modulation itself has got well defined phase transitions. |
| Answer» C. filtering. | |
| 20. |
At a given probability of error Binary coherent FSK is inferior to Binary coherent PSK by |
| A. | 6 dB |
| B. | 3 dB |
| C. | 2 dB |
| D. | 0 dB |
| Answer» C. 2 dB | |
| 21. |
Match the following Lists:List-I List-II(a) AM wave(i) \({V_C}\cos \left[ {{\omega _c}t + m\cos \left( {{\omega _m}t} \right)} \right]\)(b) FSK(ii) \(A\cos \left[ {{\omega _0}t + \phi \left( t \right)} \right]\)(c) FM wave(iii) \({V_c}\cos \left[ {2\pi \left( {{f_c} + {V_m}\left( t \right){\rm{\Delta }}f} \right)t} \right]\)(d) BPSK(iv) \(\left[ {1 + m.\sin \left( {2\pi {f_m}t} \right)} \right]\left[ {{E_c}\sin \left( {2\pi {f_c}t} \right)} \right]\)Correct code are:Code: |
| A. | a-iv, b-ii, c-i, d-iii |
| B. | a-iii, b-iv, c-i, d-ii |
| C. | a-i, b-iii, c-iv, d-ii |
| D. | a-iv, b-iii, c-i, d-ii |
| Answer» E. | |