A cordless telephone using separate frequencies for transmission in base and portable units is known as
Separate frequencies for transmission from base and portable units allows two way transmission and is called duplex arrangement.
For attenuation of high frequencies we should use
Since Xc for high frequencies is low, the high frequencies are shunted to ground and are not transmitted.
A modem is classified as low speed if data rate handled is
When data rate in bits per second is upto 600, modem is low speed.
VSB modulation is preferred in TV because
VSB (vestigial side band) transmission transmits one side band fully and the other side band partially thus, reducing the bandwidth requirement.
A woofer should be fed from the input through a
Woofer is a low frequency loud speaker covering the range 16 Hz to 500 Hz.
The colour subcarrier and sidebands produced by its modulation with the chrominance signals are accommodated in the standard channel width by the process of
In frequency interleaving the space between bundles is used for colour signal.
In FM signal with a modulation index mf is passed through a frequency tripler. The wave in the output of the tripler will have a modulation index of
Frequency multiplier increase the deviation,
In colour TV receiver, varactor diode is used for
In varactor diode the applied reverse bias controls the width and therefore capacitance of depletion layer.
This capacitance is used for tuning.
The number of noise sources in a BJT are
Shot noise, partition noise and thermal noise.
Energy content of atmospheric noise
Atmospheric noise decreases as frequency is increased.
A 400 W carrier is amplitude modulated with m = 0.75. The total power in AM is
c(t) and m(t) are used to generate an FM signal. If the peak frequency deviation of the generated FM signal is three times the transmission bandwidth of the AM signal, then the coefficient of the term cos [2p(1008 x 103t)] in the FM signal (in terms of the Bessel Coefficients) is
As, we known FM, s(t)
Frequency deviation = 3 . (AM Bandwidth) = 6 fm
and β= 6 is given in (d) only.
ωc + n ωm = (1008 x 103)2p
2p x 106 + n. 4p x 103 = (1008 x 103).2p
n = 4
So, β = 6, n = 4 hence answer is 5j4(6).
Non-coherently detection is not possible for
Tracking of extra terrestrial objects requires
All the three are required.
Assertion (A): Free space does not interfere with normal radiation and propagation of radio waves
Reason (R): Free space has no magnetic or gravitational fields.
Since free space does not have magnetic and other fields, waves can propagate without any interference.
In radar systems PRF stands for
PRF in radar systems means pulse repetition frequency.
Which of the following cannot be the Fourier series expansion of a periodic signal?
x(t) = cos t + 0.5
not satisfies the Dirichlet condition.
The integration of constant term is ∞.
Which of the following is the indirect way of FM generation?
It generates FM through phase modulation.
A telephone exchange has 9000 subscribers. If the number of calls originating at peak time is 10, 000 in one hour, the calling rate is
Calling rate is the number of calls per subscriber.
If C is capacity of noisy channel, (bits/s), δf is bandwidth Hz and S/N is signal to noise ratio, then
This is Shannon-Hartley theorem.
As the frequency increases, the absorption of ground wave by earth's surface
Because of this reason ground waves can be used for frequencies upto about 1600 kHz only.
The velocity of sound waves in air
v ∝ T.
The range of a cordless telephone is about
The range depends on quality of instrument and is about 100 m.
An earth mat for a communication tower consists of
The number of radials is large and depth is about 30 cm.
Degaussing in a picture tube means
Since gauss is a unit of magnetic flux, degaussing means removal of magnetism.