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प्रश्न
Why is Modulation index kept low?
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उत्तर
As the low-frequency modulating signal is mixed with a high-frequency carrier wave, the distortion is restricted due to the high-frequency carrier wave for modulation index lying between 0 and 1. If the amplitude of modulating wave is greater than the carrier wave then the carrier wave gets over-modulated. This over modulation results in distorted waveform envelope which will result in a distorted output signal.
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संबंधित प्रश्न
Define modulation index.
State three important factors showing the need for translating a low frequency signal into a high frequency wave before transmission
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.
Explain the need for modulation related to the size of antenna (aerial).
State any two types of modulation
The carrier wave is represented by
Define the term modulation. Draw a block diagram of a simple modulator for obtaining AM signal ?
Broadcasting antennas are generally ______.
I-V characteristics of four devices are shown in Figures.
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 |
 |
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| (i) | (ii) | (iii) | (iv) |
Identify devices that can be used for modulation.
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.
