Advertisements
Advertisements
प्रश्न
Given modulation index physical significance .For an amplitude modulated wave, the maximum amplitude is found to be 10 V while the minimum amplitude is 2 V. Determine the modulation index μ ?
Advertisements
उत्तर
Physical significance of modulation Index.
To determine the strength and quality of transmitted signal. If the modulation index is small, the amount of variation in the carrier amplitude is small. Thus, the audio signal transmitted will not be strong. The greater the degree of modulation, the stronger and clearer will be the audio signal during reception.
Maximum amplitude, Amax = 10 V
Minimum amplitude, Amin = 3 V
Thus modulating index `mu =(A_(max) -A_(min))/(A_(max) +A_(min)) = (10+3)/(10 -3) = 13/7 = 1.85`
संबंधित प्रश्न
State three important factors showing the need for translating a low frequency signal into a high frequency wave before transmission
Draw a sketch of a sinusoidal carrier wave along with a modulating signal and show how these are superimposed to obtain the resultant amplitude modulated wave
How are side bands produced?
Due to economic reasons, only the upper sideband of an AM wave is transmitted, but at the receiving station, there is a facility for generating the carrier. Show that if a device is available which can multiply two signals, then it is possible to recover the modulating signal at the receiver station.
In the block diagram of a simple modulator for obtaining an AM signal, shown in the figure, identify the boxes A and B. Write their function.
Answer the following question.
Why a signal transmitted from a TV tower cannot be received beyond a certain distance? Write the expression for the optimum separation between the receiving and the transmitting antenna.
A 20 volt AC is applied to a circuit consisting of a resistance and a coil with negligible resistance. If the voltage across the resistance is 12 volt, the voltage across the coil is ______.
Broadcasting antennas are generally ______.
An audio signal of 15kHz frequency cannot be transmitted over long distances without modulation because ______.
- the size of the required antenna would be at least 5 km which is not convenient.
- the audio signal can not be transmitted through sky waves.
- the size of the required antenna would be at least 20 km, which is not convenient.
- effective power transmitted would be very low, if the size of the antenna is less than 5 km.
A transmitting antenna has a height of 320 m and that of receiving antenna is 2000 m. The maximum distance between them for satisfactory communication in line of sight mode is 'd'. The value of 'd' is ______ km.
