Quiz Electronics Engineering 25 Aug 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 25/08/2020

Each Question carries 1 Mark
Negative Marking: 1/4
Time: 10 Minutes

Q1. Coherent demodulation of FSK signal can be detected using
(a) matched filter
(b) bandpass filters and envelope detector
(c) correlation receiver
(d) discriminator detection

Q2. Which instruction in an 8085 processor can clear the accumulator?
(a) XRA A
(b) JNZ 2100H
(c) STA 2000H
(d) MOV B, C

Q3. Difference between a switch and Hub
(a) both are same
(b) switch avoids flooding
(c) Hub avoids broadcast
(d) None of the above

Q4. In a broadside array, the maximum radiation occurs:
(a) along the array
(b) at 45° to the array
(c) perpendicular to the array
(d) None of the these

Q5. When a function f(n) is said to be left sided?
(a) f(n) = 0 for n < 0
(b) f(n) < 0 for n > 0
(c) f(n) = ∞ for n < n_o
(d) f(n) = 0 for n > n_o

Q6. Initially the number decimal 8 is stored. If instruction RAL is executed twice, the final number stored will be:
(a) Decimals 8
(b) Decimal 32
(c) Decimal 16
(d) Decimal 2

Q7. The efficiency of an LED for generating light is directly proportional to the
(a) current injected
(b) temperature
(c) applied voltage
(d) level of doping

Q8. One byte is a group of how many bits?
(a) 2 bits
(b) 4 bits
(c) 8 bits
(d) 16 bits

Q9. The frequency of DC supply is
(a) zero
(b) 16 2/3 Hz
(c) 50 Hz
(d) 100 Hz

Q10. A discrete LTI system is non-causal if its impulse response is
(a) a^nu(n – 2)
(b) a^(n-2)u(n – 2)
(c) a^(n+2)u(n)
(d) a^nu(n + 2)

SOLUTIONS

S1. Ans.(c)
Sol. The Coherent demodulation of FSK signal can be detected using correlation receiver. It is a radio-astronomy receiver in which either the noise power from a single antenna is split and multiplied with itself or the noise power from the two arms of an are multiplied together.

S2. Ans.(a)
Sol. ‘XRA’ means Exclusive OR operation is applied between the contents of the accumulator and the contents of the operand i.e. register or memory. The result is stored in the accumulator.
Here, Ex-OR operation is applied between the contents of the accumulator only. We know that if the inputs are same then the output of the Ex-OR operation will be zero. So, the final result is ‘0’ in the accumulator i.e. accumulator data is cleared.

S3. Ans.(b)
Sol. Hub and Switch both are used for connecting large number of computers together to a network. In Hub, there is no control over flow of data but in case of switch if the flow of data is over limit then it also functions in stopping those data.
difference between Hub and Switch

S4. Ans.(c)
Sol. In a broadside array, the direction of the maximum radiation is perpendicular to the axis of array but in the end fire array, the direction of the maximum radiation is along the axis of array.

S5. Ans.(d)
Sol. If a signal is having non-zero value to the left of any fixed value of n till –∞ then signal is said to be left sided.
Here, the fixed discrete time is n_o so f(n) = 0 for n > n_o.

S6. Ans. (b)
Sol. RAL(Rotate Accumulator Left) instruction rotate the accumulator towards left along with the carry present. If instruction RAL is executed once the number gets doubled.

At first RAL executed: –

Second time RAL executed: –

Therefore, the final number stored will be 25 = 32.

S7. Ans.(a)

S8. Ans.(c)

S9. Ans.(a)
Sol. In DC supply, current or voltage does not vary with time so frequency of dc supply is zero.

S10. Ans.(d)
Sol. A discrete LTI system is causal if h(n) = 0 for n < 0.
But, here h(n) ≠ 0 for n = -2 so system is non-causal.

Leave a comment

Your email address will not be published. Required fields are marked *