141. In morse code the spacing between the elements is
A. 1 dot
B. 3 dots
C. 6 dots
D. 9 dots

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142. According to Hartley's law
A. only binary codes may be used
B. the maximum rate of information transmission depends on the depth of modulation
C. the maximum rate of information depends on the channel bandwidth
D. redundancy is essential

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143. A modulator is a device to
A. extract information from the carrier
B. amplify the audio frequency signal separate two frequencies
C.(e) impress the information on to a radio frequency carrier
D.

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144. PDM is generated by using
A. JK flip-flop
B. Schmitt trigger
C. Monostable vibrator
D. Free running multivibrator

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145. By the use of which of the following the PPM can be converted to PWM?
A. Astable multivibrator
B. Integrator
C. Monostable multivibrator
D. Bistable multivibrator

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146. To modulate PCM, it is first converted into
A. PDM
B. PPM
C. PWM
D. PAM

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147. For transmission of normal speech signal, the PCM channel needs a bandwidth of
A. 16 Hz
B. 32 Hz
C. 64 Hz
D. 96 hz

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