# In a AM signal, received signal power is 10-10W with a maximum modulating signal of 5 kHz. The noise spectral density at the receiver input is10-8 W/Hz. If noise power is restricted to the message signal bandwidth only, then signals-to-noise ratio at the input to the receiver is

1.  43 dB

2.  66 dB

3.   56 dB

4.  33 dB

4

43 dB

Explanation :
No Explanation available for this question

# A carrier wave of 1 GHz and amplitude 3V is frequency modulated by a sinusoidal modulating signal frequency of 500 Hz and of peak amplitude of 1 V. The frequency deviation is 1 kHz. The peak level of the modulating waveform  changed to 5 V and the modulating frequency is changed  to 2 kHz. The expression for the new modulated wave form is

1.  cos[2πx106t+2.5cos(4πx103t)]

2.  cos[2πx106t+5cos(4πx103t)]

3.  3cos[2πx106t+2.5cos(4πx103t)]

4.  3cos[2πx106t+5cos(4πx103t)]

4

3cos[2πx106t+2.5cos(4πx103t)]

Explanation :
No Explanation available for this question

# In certain frequency-modulation experiment conducted with fm = 1 kHz and increasing amplitude (starting from 0 V), it is found that carrier component of FM signal is reduced zero for the first time when Am= 2 V. Given :Bessel function J0(x) is zero for x = 2.44, 6.52,8.65, 11.8 and so on. The frequency sensitivity of the modulator

1.  1.38kHz/V

2.  0.61 kHz/V

3.  2.761 kHz/V

4.   1.221 kHz/V

4

1.221 kHz/V

Explanation :
No Explanation available for this question

# The plot for frequency deviation is

1.

2.

3.

4.

4

Explanation :
No Explanation available for this question

# Thermister is used for measurement of power at

1.  audio frequencies

2.  high frequencies

3.  very high frequencies

4.  microwave frequencies

4

very high frequencies

Explanation :
No Explanation available for this question

# Over temperature range of -600to 1500C sensistor has temperature coefficient of resistance of about

1.  -0.5% per degC

2.  -0.2% per deg C

3.  +0.7% per deg C

4.  +2.0% per deg C

4

-0.2\% per deg C

Explanation :
No Explanation available for this question

# In a photo diode light is focused to fall on

1.  p region only

2.  n region only

3.  full p and n regions

4.  junction region only

4

n region only

Explanation :
No Explanation available for this question

# Response time of PIN photo diode is of the order of

1.  0.1ns

2.  1 ns

3.  10 ns

4.  1milli.sec

4

1 ns

Explanation :
No Explanation available for this question

# In phototransistor, light is focused to fall on

1.  emitter to base junction

2.  Collector to base junction

3.  base region only

4.  all the three regions of the transistor

4

Collector to base junction

Explanation :
No Explanation available for this question

# An npn photo transistor has typical sensitivity of the order of

1.  25μm/m W/cm2

2.  250μm/m W/cm2

3.  2.5mA/m W/cm2

4.  250mA/m W/cm2

4