If the height of transmitting and receiving antennas are $80\,m$ each,the maximum line of sight distance will be $..............\,km$. Given: Earth's radius $= 6.4 \times 10^6\,m$.

In the case of amplitude modulation,to avoid distortion,the modulation index $(\mu)$ should be:

For the output of an $AM$ detector circuit to follow the envelope of the carrier wave,which condition must be satisfied? ($T_c$ is the time period of the carrier wave.)

$A$ message signal is super-imposed with a carrier signal. The resulting modulating signal $C_m(t)$ is given by $C_m(t)=A_1 \sin \left(\omega_1 t\right)+A_2 \sin \left(\omega_2 t\right)-A_2 \sin \left(\omega_3 t\right)$,where $\omega_2 < \omega_1 < \omega_3$. The modulation index and the angular frequency of the message signal respectively,are

$A$ basic communication system consists of:
$(A)$ Transmitter $(B)$ Information source $(C)$ User of information $(D)$ Channel $(E)$ Receiver
Choose the correct sequence in which these are arranged in a basic communication system.

In the process of modulation,........