Question

2 factors which demonstrate the need for modulating a signal

Answer 1

Heya Friend,

Two factors which demonstrate the need for modulating a signal are given below :-

A message signal is also called base band signal, which usually spreads over a large range of frequencies, called the signal bandwidth. Suppose we wish to transmit an electronic signal in the audio frequency 20 Hertz to 20 Kilohertz over a long distance directly, this cannot be done due to following reasons :-

1). An antenna is needed both for transmission and reception. Each antenna should have a size comparable to the wavelength of the signal (at least Wavelength/4 in size), for an Electromagnetic wave of frequency 20 kilo hertz wavelength is 15 km. Therefore length of antenna should be equal to 15 upon 4 km which is equal to 3.75 km. Obviously such an long antenna is not possible.

Hence antenna length can be made reasonable, if the frequency is high. Hence there is need to convert low frequency signal into high frequency signal before transmission by modulation.

2). Suppose many people are talking at the same time or many transmitters are transmitting baseband information signals simultaneously. All these signals will get mixed up and there is no simple way to distinguish between them. The possible solution is to use communication at high frequencies and alloting a band of frequencies to each message signal for its transmission.

To overcome this difficulties, the message signal is superimposed on high frequency wave, some characteristics of which varies as a function of instantaneous value of signal and resulting wave, so produced is transmitted.

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I have Explained it in detail, you can also write it in short..

I hope it helped.... #Phenomenal...