MCQOPTIONS
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MCQOPTIONS
This section includes 12 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. |
For a coherent FSK with 32 levels, the probability of bit error is ______ the probability of symbol error. |
| A. | 31 times |
| B. | 1 / 31 times |
| C. | 2 times |
| D. | 0.5 times |
| Answer» E. | |
| 2. |
A satellite system employs QPSK modulation with 40% excess bandwidth per carrier including guard band. The voice channels use 64 kbps PCM coding. The no. of channels supported by 36 MHz bandwidth of the transponder in bandwidth limited case will be |
| A. | 1000 |
| B. | 800 |
| C. | 900 |
| D. | 600 |
| Answer» C. 900 | |
| 3. |
For a binary FSK signal with a mask frequency of 49 kHz, a space-frequency of 51 kHz and on the input bit rate of 2 kbps, the peak frequency deviation will be |
| A. | 0.5 kHz |
| B. | 1.0 kHz |
| C. | 2.0 kHz |
| D. | 4.0 kHz |
| Answer» C. 2.0 kHz | |
| 4. |
A carrier is modulated by a digital bit stream having one of the possible phases of 0°, 90°, 180°, and 270°. Then the modulation is termed as |
| A. | BPSK |
| B. | QPSK |
| C. | QAM |
| D. | MSK |
| Answer» C. QAM | |
| 5. |
A video camera generates data at a rate of 5 Mbps. The data is channel coded at rate 1/3 and 8 PSK modulated. Which of the following statements is correct? |
| A. | Information rate: 15 Mbps; Symbol rate: 5 Msps |
| B. | Information rate: 5 Mbps; Symbol rate: 15 Msps |
| C. | Information rate: 15 Mbps; Symbol rate: 15 Msps |
| D. | Information rate: 5 Mbps; Symbol rate: 5 Msps |
| Answer» B. Information rate: 5 Mbps; Symbol rate: 15 Msps | |
| 6. |
Coherent orthogonal binary FSK modulation is used to transmit two equiprobable symbol waveforms |
| A. | Q(2) |
| B. | \(Q\left( {2\sqrt 2 } \right)\) |
| C. | Q(4) |
| D. | \(Q\left( {4\sqrt 2 } \right)\) |
| Answer» D. \(Q\left( {4\sqrt 2 } \right)\) | |
| 7. |
For a binary phase-shift keying modulator with a carrier frequency of 70 MHz and input bit rate of 10 Mbps, the maximum Upper Side Frequency (USF) and minimum Lower Side Frequency (LSF) are respectively |
| A. | 85 MHz and 65 MHz |
| B. | 75 MHz and 65 MHz |
| C. | 55 MHz and 45 MHz |
| D. | 75 MHz and 45 MHz |
| Answer» C. 55 MHz and 45 MHz | |
| 8. |
A coherent QPSK demodulator is required on the ground for receiving data from an LEO satellite. What should be the optimum order of PLL in the carrier phase tracking loop? |
| A. | 1st order |
| B. | 2nd order |
| C. | 3rd order |
| D. | None of the above |
| Answer» D. None of the above | |
| 9. |
In a digital communication system employing Frequency Shift Keying (FSK), the 0 and 1 bit are represented by sine waves of 10 kHz and 25 kHz respectively. These waveforms will be orthogonal for a bit interval of |
| A. | 250 μsec |
| B. | 200 μsec |
| C. | 50 μsec |
| D. | 45 μsec |
| Answer» C. 50 μsec | |
| 10. |
ASK stands for: |
| A. | Amplitude Shift Keying |
| B. | Amplification Shift Keying |
| C. | Altitude Shuffle Keying |
| D. | Amplitude Shuffle Keying |
| Answer» B. Amplification Shift Keying | |
| 11. |
In binary frequency shift keying (FSK), the given signal waveforms areu0(t) = 5 cos(20000πt); 0 ≤ t ≤ T, andu1(t) = 5 cos(22000πt); 0 ≤ t ≤ Twhere T is the bit-duration interval and t is in seconds. Both u0(t) and u1(t) are zero outside the interval 0 ≤ t ≤ T. With a matched filter (correlator) based receiver, the smallest positive value of T (in milliseconds) required to have u0(t) and u1(t) uncorrelated is |
| A. | 0.25 ms |
| B. | 0.5 ms |
| C. | 0.75 ms |
| D. | 1.0 ms |
| Answer» C. 0.75 ms | |
| 12. |
Modulation scheme used in GSM is |
| A. | DPSK |
| B. | QPSK |
| C. | GMSK |
| D. | BFSK |
| Answer» D. BFSK | |