Legal Metrology • Paper-III
Reflex klystron oscillator uses
A)
one cavity resonator
B)
two cavity resonators
C)
three cavity resonators
D)
both (a) & (b)
The reflex klystron is widely used as a stable microwave local oscillator.
Legal Metrology • Paper-III
Modulation scheme which uses carrier phase shifting and synchronous detection to permit two DSB signals to occupy the same frequency band is called
A)
NBFM
B)
CDMA
C)
QAM
D)
FDMA
Correct option: C — QAM. This matches the standard definition/result for the stated question.
Legal Metrology • Paper-III
The information to be communicated in a data communication system is also called
A)
message
B)
transmission
C)
medium
D)
protocol
The information to be communicated is called the message.
Legal Metrology • Paper-III
A reflex klystron oscillator is a
A)
high efficiency device
B)
high power device
C)
low power device
D)
both (a) & (b)
The reflex klystron is widely used as a stable microwave local oscillator.
Legal Metrology • Paper-III
The maximum power efficiency of an Amplitude Modulator (AM) modulator is
A)
25%
B)
50%
C)
33%
D)
100%
Class-B operation reduces quiescent power because each transistor conducts for approximately one half-cycle.
Legal Metrology • Paper-III
Which of the following is capable of giving the highest data speed?
A)
Coaxial cable link
B)
Microwave LOS link
C)
Microwave satellite system
D)
Optical fibre system
Correct option: D — Optical fibre system. This matches the standard definition/result for the stated question.
Legal Metrology • Paper-III
Why a ROM does not have data inputs?
A)
It does not have a WRITE operations
B)
Data inputs are integrated with data outputs
C)
Data inputs are integrated with address inputs
D)
ROM is sequentially accessed
Correct option: A — It does not have a WRITE operations. This matches the standard definition/result for the stated question.
Legal Metrology • Paper-III
In PCM system, the amplitude levels are transmitted as 7-bit code words. The sampling is done at 10 kHz. The bandwidth of the system is
A)
10 kHz
B)
20 kHz
C)
35 kHz
D)
70 kHz
A 7-bit PCM stream at 10 kHz has 70 kb/s bit rate; the corresponding baseband bandwidth is about 35 kHz for ideal Nyquist signaling.
Legal Metrology • Paper-III
Time division multiplexing is used when the data to be transmitted is
A)
Slow changing
B)
Of small bandwidth
C)
Slow changing and has a small bandwidth
D)
Fast changing and has a wide bandwidth
Correct option: D — Fast changing and has a wide bandwidth. This matches the standard definition/result for the stated question.
Legal Metrology • Paper-III
In an 8085 microprocessor, the shift registers which store the result of an addition and the overflow bit are, respectively
A)
B and F
B)
A and F
C)
H and F
D)
A and C
TRAP is the highest-priority 8085 interrupt.
Legal Metrology • Paper-III
A microprocessor operates in binary digits, 0 and 1, also known as ___________.
A)
Bytes
B)
Decimal number
C)
Octal number
D)
Bits
Correct option: D — Bits. This matches the standard definition/result for the stated question.
Legal Metrology • Paper-III
Each manufacturer of a microprocessor has devised a symbolic code for each instruction (written in hexadecimal code), called a
A)
Mnemonic
B)
Low level code
C)
Microcode
D)
Microcontroller
Correct option: A — Mnemonic. This matches the standard definition/result for the stated question.
Legal Metrology • Paper-III
In digital communication system, the data transmission rate is specified in
A)
MHz
B)
Bits/sec
C)
Bytes/sec
D)
Bauds
Digital bit rate is expressed in bits per second.
Legal Metrology • Paper-III
The interrupt lines in 8085 is
A)
8
B)
3
C)
5
D)
7
TRAP is the highest-priority 8085 interrupt.
Legal Metrology • Paper-III
ALU (Arithmetic and Logic Unit) of 8085 microprocessor consists of
A)
Accumulator, temporary register, arithmetic and logic circuits
B)
Accumulator, temporary register, arithmetic, logic circuits and five flags
C)
Accumulator, arithmetic and logic circuits
D)
Accumulator, arithmetic, logic circuits and five flags
TRAP is the highest-priority 8085 interrupt.
Legal Metrology • Paper-III
TEM wave cannot propagate in which one of the following?
A)
Two wire transmission line
B)
Coaxial cable
C)
Rectangular waveguide
D)
Micro-strip line
A single-conductor hollow rectangular waveguide cannot support a TEM mode.
Legal Metrology • Paper-III
Microwave antenna is of____________.
A)
Pattern type
B)
Aperture type
C)
Metallic type
D)
None of these
Correct option: B — Aperture type. This matches the standard definition/result for the stated question.
Legal Metrology • Paper-III
Which of the following analog modulation scheme requires the minimum transmitted power and minimum channel band-width?
A)
VSB
B)
DSB-SC
C)
SSB
D)
AM
SSB suppresses the carrier and one sideband, minimizing both power and bandwidth among conventional AM schemes.
Legal Metrology • Paper-III
In a microwave magic T, E plane and H plane are
A)
In phase
B)
Out of phase
C)
Isolated
D)
90° out of phase
The E-arm and H-arm are isolated from each other.
Legal Metrology • Paper-III
In communication systems, modulation is the process of
A)
Improving frequency stability of transmitter
B)
Combining signal and radio frequency waves
C)
Generating constant frequency radio waves
D)
Reducing distortion in RF waves
Correct option: B — Combining signal and radio frequency waves. This matches the standard definition/result for the stated question.
Legal Metrology • Paper-III
In electromagnetic waves, polarisation is
A)
due to transverse nature of waves
B)
always vertical in isotropic medium
C)
due to longitudinal nature of waves
D)
caused by reflection of waves
Correct option: A — due to transverse nature of waves. This matches the standard definition/result for the stated question.
Legal Metrology • Paper-III
The number of bits per sample in a PCM is increased from 8 to 16. The bandwidth of the system will increase
A)
8 times
B)
2 times
C)
Half times
D)
28 times
A 7-bit PCM stream at 10 kHz has 70 kb/s bit rate; the corresponding baseband bandwidth is about 35 kHz for ideal Nyquist signaling.
Legal Metrology • Paper-III
Which of the following does not cause losses in optical fibre cables?
A)
Impurities
B)
Micro bending
C)
Attenuation in glass
D)
Stepped index operation
Stepped-index operation is a fibre type, not a loss mechanism.
Legal Metrology • Paper-III
Tropospheric scatter communication is used for which frequency band?
A)
HF
B)
VHF
C)
UHF
D)
VLF
Correct option: B — VHF. This matches the standard definition/result for the stated question.
Legal Metrology • Paper-III
In TWT attenuator is used to
A)
Help bunching
B)
Prevent oscillation
C)
Prevent saturation
D)
Increase gain
An attenuator suppresses feedback and prevents unwanted oscillation in a TWT.
