Digital signal

For an $FM$ carrier with a carrier frequency of $200 \text{ kHz}$ and a modulating frequency of $10 \text{ kHz}$,the modulation index is...

Ultra high frequency $(UHF)$ band stands for

Which of the following modulated signals has the best noise tolerance?

$A$ transmitting antenna can cover an area of $6.4\pi \times 10^9 \ m^2$ when used for broadcasting. If the signal is transmitted to another antenna,which is at a distance of $100 \ km$ from this antenna,what should be the minimum height of the receiving antenna for satisfactory communication in line-of-sight mode (in $m$)? (Assume the radius of the Earth $R = 6400 \ km$)

The height of a $TV$ transmission tower is $240 \ m$. Up to what distance can the transmission be received (in $km$)? (Radius of the Earth $R = 6.4 \times 10^6 \ m$)