All Q&A

Compare PAM, PWM and PPM

24 July, 2024
PAM, PWM and PPM stands for Pulse Amplitude Modulation, Pulse Width Modulation and Pulse Position Modulation. In the PAM system carrier signal is rectangular pulse and that is why this system is called PAM.

Find the Fourier transform of the following:

Fig. 1

24 July, 2024
From the figure, we have the function x(t) = 1 for 0 < t ≤ τ/2 and otherwise x(t) = 0

Draw the block diagram of a super heterodyne receiver. Explain the function of each block. Explain the significance of the name super hetero dyne. How RF sections suppress the image channel? Why is up – conversion used in super heterodyne receive? Define image Rejection Ratio.

24 July, 2024
Super heterodyne receivers was proposed as an alternative to TRF receiver which suffers from selectivity problem .The basic super heterodyne receiver is most widely used receivers at present. Super heterodyne principal is also used in television and radar receiver. In the super heterodyne receivers, the received RF signal voltage is combined with the local oscillator voltage and is converted into a signal of lower fixed frequency.

"FM and PM are different but inseparable." – Justify the statement.

24 July, 2024
The expression for FM and PM are almost identical. FM and PM cannot be distinguished at a constant modulating frequency.

What are Narrowband FM and Wideband FM?

24 July, 2024
A narrow band FM is the FM wave with a small bandwidth. The modulation index β of narrow band FM is small as compared to one radian. Hence, the spectrum of narrowband FM consists of the carrier and upper side band and lower side band.

Explain with proper expression

  • Modulation index
  • Bandwidth required for transmission of FM
24 July, 2024
The modulation index in AM wave is defined as the ratio between amplitude of the modulating signal and amplitude of the carrier signal. The mathematical representation is given below