Advertisements
Advertisements
Question
What is the function of a bandpass filter used in a modulator for obtaining AM signal?
Advertisements
Solution
The output produced by the square-law device is passed to the bandpass filter which rejects the dc and the sinusoids of frequencies wm, 2wm, and 2wc and retains the frequencies wc, wc – wm, and wc + wm. The output of the bandpass filter is an AM wave.
APPEARS IN
RELATED QUESTIONS
Explain the terms Attenuation used in Communication System.
Write the functions of the following in communication systems:
Transmitter
Write the functions of the following in communication systems:
Transducer
Distinguish between broadcast mode and point-to-point mode of communication and give one example for each.
A device X used in communication system can convert one form of energy into another. Name the device X. Explain the function of a repeater in a communication system.
Distinguish between point to point and broadcast modes of communication. Give an example of each.
Write the functions of the transducer and repeaters.
Audio sine waves of 3 kHz frequency are used to amplitude modulate a carrier signal of 1.5 MHz. Which of the following statements are true?
- The sideband frequencies are 1506 kHz and 1494 kHz.
- The bandwidth required for amplitude modulation is 6 kHz.
- The bandwidth required for amplitude modulation is 3 MHz.
- The side band frequencies are 1503 kHz and 1497 kHz.
Figure shows a communication system. What is the output power when input signal is of 1.01 mW? (gain in dB = 10 log10 (Po/Pi).
An audio signal is modulated by a carrier wave of 20 MHz such that the bandwidth required for modulation is 3 kHz. Could this wave be demodulated by a diode detector which has the values of R and C as
- R = 1 kΩ, C = 0.01 µF.
- R = 10 kΩ, C = 0.01 µF.
- R = 10 kΩ, C = 0.1 µF.
