A total of 16 equally probable events exist. If it is required to select one out of them, the number of required bits is
24 = 16.
When modulation index of an AM wave is increased from 0.5 to 1, the transmitted power
Quantizing error occurs in
An analog number cannot be converted into an exact digital number.
This is called quantizing error.
In audio cassettes the width of each recording track is
Each track is 2.5 mm wide.
The most commonly used transistor amplifier circuit is
Common emitter connection has high power gain, and good current and voltage gains.
When energy is fed into open wire transmission line the energy may get dissipated due to
All the three cause dissipation of energy as heat.
Fourier series expansion of a real periodic signal with fundamental frequency is given by It is given that c3 = 3 + j5. then c-3 is
For real signal
ck = c*-k
3 - i5.
Loudness control gives
For depth in sound the low frequency notes, (i.e., bass) need more amplification.
If transmitted power is 75 kW, the field strength at 30 km distance will be about
Using the derivation,
A mobile telephone has a range of about
Mobile telephone has about 50 km range.
In the television system in India, each frame is scanned
Each frame is divided into odd and even fields. Each field is scanned 25 times so that each frame is scanned 50 times.
Each kilometer of travel in electromagnetic radiation means a time delay of
Since velocity of em waves is 300 m/ms, each kilometer means time delay of 3.3 μs.
A video monitor is exactly similar to TV receiver.
Trinitron is a colour picture tube.
A RADAR can be used to
Radar is used for all the three purposes.
In single tone AM modulation, the transmission efficiency for m = 1 is
Since signal power = 0.5 PC and total power is 1.5 PC efficiency is 33.3%.
AM amplifier having noise figure of 20 dB and available power gain of 15 dB is followed by a mixer circuit having noise figure of 9 dB. The overall noise figure as referred to input in dB is
If the oscillator output is modulated by audio frequencies upto 10 kHz, the frequency range occupied by the side bands will be
Sideband frequencies will be fc fm.
Which one of the following is non-resonant antenna?
Rhombic antenna is a non-resonant antenna capable of operating over 3 to 30 MHz range.
The efficiency of using a binary system for selection of 1 out of 13 equally probable events is
log2 13 = 3.7 therefore, number of bits = 4.
The most suitable method for detecting a modulated signal g(t) = (3 to 6 cos 2pfmt) cos 2pfct is
Because it is an AM envelope.
The time required for horizontal blanking is 16% of that for each horizontal line. If horizontal time is 63.5 μs, the horizontal blanking time for each line is about
A message signal with bandwidth 10 kHz is lower sideband SSB modulated with carrier frequency fc1 = 106 Hz. The resulting signal is then passed though a narrow band frequency modulator with carrier frequency fc2 = 109 Hz. The bandwidth of the output would be
Bandwidth = 2Δf + 2B
But for NBFM, B < 1
BW ≈ 2fm 2fc1 2 x 106 Hz.
When the number of quantising levels is 16 in PCM, the number of pulses in a code group will be
2n = L n = 4.
In a PCM system, if the code word length is increased from 6 to 8 bits, the signal to quantization noise ratio improves by the factor.
Given n1 = 6, n2 = 8,
then (SNR)Q = 22(n2 - n1) 16.
For 10 bit PCM system, the signal to quantization noise ratio is 62 dB. If the number of bits is increased by 2, then the signal to quantization noise ratio will
= (SNR)Q + 6.02 x 2 (SNE)Q + 12 dB.