Question

An angle modulated signal is generated by using message
Signal m(t) = sin (2000Pit) V. if Kf=100 Hz/V and kp=10 rad/V, find the partical bandwidth of FM and PM signal. Determine the practical bandwidth of the FM and PM signal in Following cases: (a) Message signal amplitude is doubled .
(b) Message signal frequency is doubled.
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Answer 1

Answer:

Explanation:

Carrier signals are used for two reasons:

(1) To reduce the wavelength for efficient transmission and

reception (the optimum antenna size is ¼ of a wavelength). A

typical audio frequency of 3000 Hz has a wavelength of 100 km and

would need an effective antenna length of 25 km! By comparison, a

typical FM carrier is 100 MHz, with a wavelength of 3 meters, and

would have an 80 cm long antenna (that is 31.5 inches long).

(2) To allow simultaneous use of the same channel, called

multiplexing. Each unique message signal has a different assigned

carrier frequency (e.g., radio stations) and share the same channel.

The telephone company invented modulation to allow phone

conversations to be transmitted over common phone lines.

Mandated by the FCC