# Angle Modulation – Exercise – 1

1. In FM the carrier deviation is determined by –

(a)  Modulating
(b)  Frequency
(c)  Either of the above
(d)  None of the above

Explanation
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2. Pre- emphasis is used to amplify –

(a)  Low frequency
(b)  High frequency
(c)  Both a and b above
(d)  None of the above

Explanation
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3. In FM –

(a)  Noise decreases by increasing deviation
(b)  Noise decreases by decreases deviation
(c)  Noise decreases by maintaining deviation constant
(d)  None of the above

Explanation
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4. Which of the following oscillator is not in FM –

(a)  Crystal oscillator
(b)  Hartley oscillator
(c)  Colpitts oscillator
(d)  All of the above

Explanation
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5. The frequency of the stereo sub carrier signal in FM broadcasting is –

(a)  19 kHz
(b)  38 kHz
(c)  50 kHz
(d)  76 kHz

Explanation
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6. The difference between phase and frequency modulation :

(a)  Lies in the different definition of the modulation index
(b)  Is too great to make the two systems compatible
(c)  Is purely theoretical because they are the same in practice
(d)  Lies in the poorer radio response of phase modulation index

Explanation
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7. Which one of the following is not necessarily an advantage of FM over AM ?

(a)  Better noise immunity is provided
(b)  The transmitted power is more useful
(c)  Lower bandwidth is required
(d)  Less modulating power is required

Explanation
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8. In FM, the frequency deviation is :

(a)  Constant
(b)  Zero
(c)  Proportional to modulating frequency
(d)  Proportional to amplitude of modulating signal

Explanation
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9. In phase modulated signal, the frequency deviation proportional to :

(a)  Frequency only
(b)  Amplitude only
(c)  Both a and b
(d)  None of the above

Explanation
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10. In carrier system, frequency fogging is used to :

(a)  Reduce noise
(b)  Reduce cross talk
(c)  Converse frequencies
(d)  Reduce distortion

Explanation
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(a) (b) (c) (d) Answer : () [/su_spoiler]
Explanation
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12. If signal band limited to fm is sampled at a rate less than 2 fm., the reconstructed signal will :

(a)  Be smaller in amplitude
(b)  Have higher frequencies suppressed
(c)  Be distorted
(d)  All the above

Explanation
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13. De-emphasis circuit is used :

(a)  Before detection
(b)  After detection
(c)  Before modulation
(d)  After modulation

Explanation
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14. Pre-emphasis is used to amplify …………… frequencies.

(a)  Low
(b)  High
(c)  Both a and b
(d)  None of the above