Quiz 5

A low pass signal band limited to 1200 Hz was sampled and it was found that the 1000 Hz frequency component was reappearing in the recovered signal, because of aliasing, as 400 Hz component. The sampling frequency used is

• 1400 Hz

• 1600 Hz

• 2200 Hz

• 800 Hz

• 2400 Hz

The distortion in the signal arising from aperture effect, can be reduced by

• reducing the width of the pulses used for flat-top sampling

• reducing the sampling frequency

• properly band limiting the signal before sampling it

• using flat-top sampling

The impulse response function, h(t), of a zero-order-hold circuit is

• an impulse

• a rectangular pulse

• a triangular pulse

• None of these

 $x\left(t\right)\ =\ 3\ \cos^2\left(250\pi t\right)$  
This signal is sampled at regular intervals of T sec. The maximum value of T for which x(t) may be recovered from the sampled version without any distortion is equal to

• 1 ms

• 2 ms

• 4 ms

• 0.5 ms

• 0.25 ms

A band limited low pass signal is sampled at twice its Nyquist rate with fs = 2000 samples/sec. The signal is band limited to

• 250 Hz

• 500 Hz

• 1000 Hz

• 750 Hz

A certain low pass signal x(t) is sampled and the spectrum of the sampled version has guard band from 1500 Hz to 1900 Hz. The sampling frequency used is

• 3000Hz

• 3800 Hz

• 3600 Hz

• 3400 Hz

 $x\left(t\right)\ =\ 5\ \cos\ 240\pi t$  was sampled. The signal recovered from the samples was, however, found to be  $3\ \cos\ 110\pi t$ . The sampling frequency is equal to

• 175 Hz

• 350 Hz

• 65 Hz

• 150 Hz

For a 12 bit uniform quantizer with voltage range -10V to +10V

• Step size is 4.9 mV

• Maximum quantization error is 2.45 mV

• Step size is 4.5 mV

• Step size is 1.67 mV

• Maximum quantization error is 2 mV

12 speech signals, each band limited to 3.5 kHz, and sampled at a rate of 8 kHz, are to be transmitted as PAM signals over a certain channel using time division multiplexing. Assuming a guard time of half the pulse width,

• Pulse width is 6.94 microsec

• Guard Time is 3.47 microsec

• Pulse width is 4.86 microsec

• Pulse width is 2.58 microsec

• Guard Time is 1.56 microsec

A signal is bandlimited from 15KHz to 25KHz. Minimum sampling frequency for distortionless transmission is

• 25 KHz

• 50 KHz

• 30KHz

• 20 KHz