An audio signal is sent on a carrier wave of frequency 30MHz. The minimum length of the antenna at the transmitting station must be (in m).
The modulation index is 0.75. The useful power available in the side bands nearby
The total power content of AM wave is 1320 W. The percentage modulation if each side band contains 160 W is
A TV tower has a height of 70 m. If the average population density around the tower is 1000 k m – 2 , the population covered by the TV tower is (Radius of Earth is 6400 km )
If an AM transmitter shows an antenna current of 8 A when only carrier is transmitted and 9 A when current is modulated using sine wave. Then, the modulation index is
If a line of sight radio communication, a distance of about 50 km is kept between the transmitting and receiving antennas. If the height of the receiving antenna is 70 m, then the minimum height of the transmitting antenna should be (Radius of the earth = 6.4 × 10 6 m)
If an AM transmitter shows an antenna current of 8 A when only carrier is transmitted and 9 A when current is modulated using sine wave. Then, the modulation index is
In an AM wave , maximum voltage was found to be 16 V and minimum voltage was found to be 4 V, the percentage of modulation is
When the percentage Modulation is 75, an AM transmitter produces 10 kW Power. The percentage power saving if carrier and one of the side band is suppressed is
An AM wave is expressed as E = 10 ( 1 + 0.6 C o s 2000 π t ) C o s 2 × 10 8 π t V o l t s , the minimum and maximum values of modulated carrier wave are
A message signal of frequency 100 MHz and peak voltage 100 V is used to execute amplitude modulation on a carrier wave of frequency 300 GHz and peak voltage 400 V . The modulation index and difference between the two side band frequencies are
An amplitude modulated wave is represented by the expression v m = 5 1 + 0.4 cos 6280 t sin 211 × 10 4 t volts. The minimum and maximum amplitudes of the amplitude modulated wave are, respectively
A TV tower has a height of 60 m. What is the maximum area up to which TV transmission can be received? Take radius of earth R = 6 .4 × 10 6 m
A TV tower has a height of 150m. By how much the minimum height (in meters) of the tower be increased so as to double the radius of its coverage range?
An audio signal is sent on a carrier wave of frequency 30MHz. The minimum length of the antenna at the transmitting station must be (in m).
A 360 W carrier wave is simultaneously modulated by two audio waves with modulation percentages of 55 and 65 respectively. Then total side band power is
For a television network , 5 × 10 5 channels are granted. If the central frequency of the microwave link is 25 GHZ and the allotted band width for each channel is 2 KHZ, how much percentage of link is used for the network?
The audio signal voltage is given by V m = 2 s i n 12 π × 10 3 t . The band width and LSB if carrier wave has a frequency 3.14 × 10 6 r a d / s
Calculate modulation index of carrier waves is modulated by three signals with modulation indices as 0.6, 0.3 and 0.4
For sky wave propagation of 10 MHz signal. What should be the minimum electron density in the ionosphere
The tuned circuit of an oscillator in a simple AM transmitter employs a 250 micro henry Coil and 1 nf condenser. If the oscillator output is modulated by audio frequency upto 10 KHz, the frequency range occupied by the side bands in KHz is
A 1000 KHz carrier is simultaneously modulated with f m 1 = 300 H z , f m 2 = 800 H z and f m 3 = 1 k H z audio sine waves. What will be the frequencies present in the output? (a) f L S B 1 = 999.7 k H z f U S B 1 = 1000.3 k H z (b) f L S B 2 = 999.2 k H z f U S B 2 = 1000.8 k H z (c) f L S B 3 = 999 k H z f U S B 3 = 1001 k H z (d) f L S B 3 = 990 k H z f U S B 3 = 1010 k H z
A telephonic communication service is working at carrier frequency of 10 GHz. Only 10 % of it is utilized for transmission. How many telephonic channels can be transmitted simultaneously, if each channel requires a bandwidth of 5 KHz?
The maximum distance between the transmitting and receiving TV towers is 64 Km. If the ratio of the heights of the TV transmitting tower to receiving tower is 4:9, the heights of the transmitting and receiving towers are
A carrier wave is modulated by a number of sine waves with modulation indices 0.1, 0.2, 0.3. The total modulation index (m) of the wave is
When only carrier is transmitted antenna current observed is 8 A when it is modulated with 500 Hz sine wave antenna current becomes 9.6 A. The percentage of modulation is
When height of the tower is increased by 21 % then transmission range of tower will be affected by x % then what is x
A fax message is to be sent from Delhi to Washington via a geostationary satellite. If the minimum time delay between the dispatch and its getting received , is y × 10 − 2 sec, then y is (Height of geostationary satellite = 36,000 km)
A transmitting antenna at the top of a tower has a height of 45 m and the receiving antenna is on the ground. If the maximum distance between them for satisfactory communication in Line Of Sight mode ( R = 6.4 × 10 6 m ) is y × 10 3 m then y is
Consider an optical communication system operating at λ = 800 n m . Suppose only 1 % of optical frequency is available for channel bandwidth for optical communication. If number of channels can be accommodated for transmitting audio signals required a bandwidth of 5 kHz is y × 10 7 , then y is
An optical communication system, having an operating wavelength λ , can use on y % of its source frequency as its channel band width. The system is to be used for transmitting TV signals requiring a bandwidth of N hertz, number of channels can transmit simultaneously, is C y ( 2 × z ) λ N then z is
The antenna current of an AM transmitter is 8A, when only Carrier is sent. It increased to 8.93 A , when the carrier is modulated by 9 single sine wave. The percentage modulation.
For a television network 10 × 10 5 channels are granted. If the central frequency of the microwave link is 50 GHZ and the allotted band width for each channel is 2 KHz, how much percentage of link is used for the network ?
If the percentage of modulation is 50 % then the useful power in the AM wave is
On certain day, it is observed that the signals of higher than 5 MHz are not received by reflection, from F 1 layer of ionic sphere. The approximate maximum electron density of F 1 layer on the day is
1 kW carrier is modulated to a depth of 80 % . The total power (in kW) in the modulator wave is
The expression for an AM voltage is e = 5 1 + 0. 6Cos1 000 π t Cos5 × 10 6 π t . Frequencies of sideband is
A carrier is modulated simultaneously by 3 sine waves of modulation indices 0.3, 0.4 and 0.45 respectively. The net modulation index is
An amplitude modulated voltage is expressed as e = 10 ( 1 + 0.6 c o s 2000 π t ) c o s ( 3 × 10 6 π t ) v o l t . The minimum and maximum value of modulated carrier wave is
A 600 W carrier is modulated to a depth of 75 % by a 400 Hz sine wave. The total antenna power is
A TV transmission tower has a height of 140 m and the height of the receiving antenna is 40 m. What is the maximum distance up to which signals can be broadcasted from this tower in LOS( Line Of Sight) mode? ( Take radius of earth R = 6.4 × 10 6 m )
In communication system, only one percent frequency of signal of wavelength 900 nm can be used as band width. How many channel of 6MHz band width can broadcast this? c = 3 × 10 8 m / s , h = 6.6 × 10 − 34 J − s
A 100 V carrier wave is made to vary between 160 V and 40 V by a modulating signal. What is the modulation index?
The modulation frequency of an AM radio station is 250 kHz , which is 10% of the carrier wave. If another AM station approaches you for license, what broadcast frequency will you allot?
The output current of a 60 % Modulated AM generator is 1.5 A. To what value will the current rise, if the generator is additionally modulated by another audio wave of modulation index 0.7 ?
The maximum distance between the transmitting and receiving antenna TV tower is D. If the heights of both towers are halved then maximum distance between them becomes
The tuned circuit of the oscillator in a simple AM transmitter employs 40 μ H coil and 12 nano-farad (nF) capacitor. If the oscillator output is modulated by audio frequency of 5 kHz, which of the following frequencies doesn’t appear in the output AM?
The maximum peat-to-peak voltage of an A.M wave is 32 mV and the minimum peak-to-peak voltage is 8 mV. The modulation factor is equal to
If a transmitting antenna at the top of a tower has a height of 49 m and the height of receiving tower is 100 m . Calculate the maximum distance between them for satisfactory communication in LOS (Line Of Sight ) mode ( R = 6400 k m ) is z × 10 3 m . Then z is(nearly)
A fax message is to be sent from Delhi to Australia via a geostationary satellite. Calculate the minimum time delay between the dispatch and its getting received is y × 10 − 3 (in sec) , then y is (Height of geostationary satellite = 36,000 km)
A TV transmission tower at a particular station has a height of 160 m radius of earth is 6400 km. i. The range it covers is 45255 m (approx). ii. The population that it covers is 77.2 lakhs (approx) when population density is 1200 k m − 2 iii. The height of antenna should be increased by 480 m to double the coverage range.
If the sum of the heights of transmitting and receiving antenna in LOS Communication is h . The range is maximum when the two antenna have a height h c , then c is
An optical communication system, having an operating wavelength λ , can use only x % of its source frequency as its channel band width. The system is to be used for transmitting TV signals requiring a bandwidth of F hertz. Number of channels transmit simultaneously, is C x ( 10 × y ) λ F then y is
Microwave telephonic link operating at the centre frequency of 10 GHz has been established. If 4 % of this is available for microwave communication channel, then no channels can be granted. If each telephone is allotted a bandwidth of 8 kHz is P × 10 3 then P is
Consider an optical communication system operating at λ = 600nm. Suppose, only 1% of the optical source frequency is the available channel bandwidth for optical communication. Number of channels that can be accommodated for transmitting audio signals requiring a bandwidth of 8kHz are × 10 8
A signal of frequency 20 kHz and peak voltage of 5V is used to modulate a carrier wave of frequency 1.2 MHz and peak voltage 25V choose the correct statement regarding amplitude modulation
A carrier wave of peak voltage 12V is used to transmit a message signal. The peak voltage of modulating signal in order to have a modulation index as 0.75 is :
A TV tower has a height of 150m.The area of the region covered by the TV broadcast is (Radius of earth = 6.4 × 10 6 m )
