MCQOPTIONS
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MCQOPTIONS
This section includes 20 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. |
A radio channel has a bandwidth of 10 kHz and an S / N ratio of 15 dB. The maximum data rate that can be transmitted is: |
| A. | 16.1 kb /sec |
| B. | 24.2 kb /sec |
| C. | 32.3 kb /sec |
| D. | 50.3 kb /sec |
| Answer» E. | |
| 2. |
An Ideal power limited communication channel with additive white Gaussian noise is having 4 kHz band width and Signal to Noise ratio of 255. The channel capacity is: |
| A. | 8 kilo bits / sec |
| B. | 9.63 kilo bits / sec |
| C. | 16 kilo bits / sec |
| D. | 32 kilo bits / sec |
| Answer» E. | |
| 3. |
Consider channel capacity is 100 Mbps, mean frame length is 10000 bits and average frame arrival rate is 5000 frames / sec. Applying simple queuing theory, the mean frame delay to send a frame onto the channel is: |
| A. | 200 micro seconds |
| B. | 100 micro seconds |
| C. | 0.5 seconds |
| D. | 2 mili seconds |
| Answer» B. 100 micro seconds | |
| 4. |
Discrete source S1 has 4 equiprobable symbols while discrete source S2 has 16 equiprobable symbols. When the entropy of these two sources is compared, the entropy of: |
| A. | S1 is greater than S2 |
| B. | S1 is less than S2 |
| C. | S1 is equal to S2 |
| D. | Depends on rate of symbols/second |
| Answer» C. S1 is equal to S2 | |
| 5. |
An event has two possible outcomes with probability \(P_1=\frac{1}{2}\), and \(P_2=\frac{1}{64}\) The rate of information with 16 outcomes per second is: |
| A. | (38/4) bits/sec |
| B. | (38/64) bits/sec |
| C. | (38/2) bits/sec |
| D. | (38/32) bits/sec |
| Answer» B. (38/64) bits/sec | |
| 6. |
A communication channel is having a bandwidth of 3000 Hz. The transmitted power is such that the received Signal-to-Noise ratio is 1023. The maximum data rate that can be transmitted error-free through the channel is: |
| A. | 3 Kbps |
| B. | 30 Kbps |
| C. | 3 Mbps |
| D. | 300 Kbps |
| Answer» C. 3 Mbps | |
| 7. |
If there are M messages and each message has probability p = 1/M, the entropy is |
| A. | 0 |
| B. | 1 |
| C. | \({\log _2}M\) |
| D. | \(M{\log _2}M\) |
| Answer» D. \(M{\log _2}M\) | |
| 8. |
Directions: The item consists of two statements, one labeled as the ‘Assertion (A)’ and the other as ‘Reason (R)’.You are to examine these two statements carefully and select the answers to the item using the codes given below:Assertion (A): Source produces two symbols A and B with probability 3/4 and 1/4 respectively. For error-free transmission, this source should be coded using Shannon-Fano code.Reason (R): For better transmission efficiency, source and channel must be matched. |
| A. | Both A and R individually true and R is the correct explanation of A |
| B. | Both A and R are individually true but R is not the correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» E. | |
| 9. |
Entropy of a discrete random variable with possible values {x1 x2, ..., xn} and probability density function P(X) is:\(H\left( X \right) = - \mathop \sum \limits_{i = 1}^n P\left( {{x_i}} \right){\log _{\rm{b}}}P\left( {{x_i}} \right)\)The value of b gives the units of entropy. The unit for b = 10 is: |
| A. | bits |
| B. | bann |
| C. | nats |
| D. | deca |
| Answer» D. deca | |
| 10. |
A source emits bit 0 with probability 1/3 and bit 1 with probability 2/3. The emitted bits are communicated to the receiver. The receiver decides for either 0 or 1 based on the received value R. It is given that the conditional density functions of R are as\({{\rm{f}}_{\left( {{\rm{R}}/0} \right)}}\left( {\rm{x}} \right) = \left\{ {\frac{1}{4}, - 3 \le {\rm{x}} \le 1} \right.{\rm{and\;}}{{\rm{f}}_{\left( {{\rm{R}}/1} \right)}}\left( {\rm{x}} \right) = \left\{ {\frac{1}{6}, - 1 \le {\rm{x}} \le 5} \right.\) The minimum decision error probability is |
| A. | 0 |
| B. | \(\frac{1}{{12}}\) |
| C. | \(\frac{1}{9}\) |
| D. | \(\frac{1}{6}\) |
| Answer» E. | |
| 11. |
Consider a discrete memoryless source with source alphabet S = {s0, s1, s2} with probabilities:\(P\left( {{s_0}} \right) = \frac{1}{4},P\left( {{s_1}} \right) = \frac{1}{4}~and~P\left( {{s_2}} \right) = \frac{1}{2}\)The entropy of the source is |
| A. | \(\frac{1}{2} ~bit\) |
| B. | \(\frac{2}{3} ~bit\) |
| C. | \(\frac{3}{2} ~bit\) |
| D. | \(\frac{1}{3} ~bit\) |
| Answer» D. \(\frac{1}{3} ~bit\) | |
| 12. |
Consider a binary memoryless channel characterized by the transition probability diagram shown in the figure.The channel is |
| A. | lossless |
| B. | noiseless |
| C. | useless |
| D. | deterministic |
| Answer» D. deterministic | |
| 13. |
Conveniently information I(x) is expressed as: |
| A. | (-) log10 p(x) Hartleys |
| B. | log10 p(x) Hartleys |
| C. | log2 p(x) Hartleys |
| D. | \(2 log_{10}\frac{1}{p(x)}\)Hartleys |
| Answer» B. log10 p(x) Hartleys | |
| 14. |
500 Bytes of data needs to be transmitted from a UART every 100 ms. What should be the minimum transmission baud rate of UART, assuming 1 start bit, 8 data bits, and 2 stop bits? |
| A. | 50000 |
| B. | 55000 |
| C. | 40000 |
| D. | 45000 |
| Answer» C. 40000 | |
| 15. |
In the communication system, if for a given rate of information transmission requires channel bandwidth, B1 and signal-to-noise ratio SNR1. If the channel bandwidth is doubled for same rate of information then a new signal-to-noise ratio will be |
| A. | SNR1 |
| B. | 2SNR1 |
| C. | \(\sqrt {SN{R_1}}\) |
| D. | \(\frac{{SN{R_1}}}{2}\) |
| Answer» D. \(\frac{{SN{R_1}}}{2}\) | |
| 16. |
A (7, 4) block code has a generator matrix as shown.\(G = \left[ {\begin{array}{*{20}{c}}1&0&0&0&1&1&0\\0&1&0&0&0&1&1\\0&0&1&0&1&1&{1}\\0&0&0&1&1&0&1\end{array}} \right]\)If there is error in the 7th Bit then syndrome for the same will be |
| A. | 001 |
| B. | 010 |
| C. | 100 |
| D. | 011 |
| Answer» B. 010 | |
| 17. |
For a fast communication which of the following requirements have to be met |
| A. | Large bandwidth |
| B. | High S/N ratio |
| C. | High channel capacity |
| D. | None of the above |
| Answer» D. None of the above | |
| 18. |
An Ideal power limited communication channel with additive white Gaussian noise with 1 MHz bandwidth and Signal to Noise Ratio of 15 is transmitting the information at the theoretical maximum rate. If the Signal to Noise ratio is reduced to 7, how much bandwidth is required to maintain the same rate: |
| A. | 15 / 7 MHz |
| B. | 4 / 3 MHz |
| C. | 2 MHz |
| D. | None of these |
| Answer» C. 2 MHz | |
| 19. |
An analog signal is band limited to 4 kHz. It is sampled at the Nyquist rate and samples are quantized into 4 levels. The quantization levels have probabilities 1/8, 1/8, 3/8 and 3/8. The information rate of the source is: |
| A. | 15400 bps |
| B. | 4000 bps |
| C. | 14400 bps |
| D. | 16000 bps |
| Answer» D. 16000 bps | |
| 20. |
A source produces 4 symbols with probabilities 1/2, 1/4, 1/8 and 1/8. For this source, a practical coding scheme has an average code word length of 2 bits / symbol. The efficiency of the code is: |
| A. | 1 |
| B. | 7 / 8 |
| C. | 1 / 2 |
| D. | 1 / 4 |
| Answer» C. 1 / 2 | |