Which one of the following is not classified as pulse modulation?

Given below in the left column are different modes of communication using the kinds of waves given in the right column.

$A$. Optical Fiber Communication	$P$. Ultrasound
$B$. Radar	$Q$. Infrared Light
$C$. Sonar	$R$. Microwaves
$D$. Mobile Phones	$S$. Radio Waves

From the options given below, find the most appropriate match between entries in the left and the right column.

The bit rate for a signal,which has a sampling rate of $8 \, kHz$ and where $16$ quantisation levels have been used,is ......... $bits/sec$.

In a communication system,a repeater is used to extend the range of transmission. It is a combination of:

The required height of a $TV$ tower which can cover the population of $6.03$ lakh is $h$. If the average population density is $100$ per square $km$ and the radius of the Earth is $6400 \, km$,then the value of $h$ will be $... \, m$.

The waves which are reflected back to the earth by the ionosphere are: