ASK system:

• ASK is a digital modulation technique defined as the process of shifting the amplitude of the carrier signal between two levels , depending on whether 1 or 0 is to be transmitted .

• Let the message be binary sequence of 1’s and 0’s . It can be represented as a function of the time as follows :

  $v_m=V_m$ when symbol is 1

  =0 when symbol is 0

• Time domain representation of generation of ASK signal (a)message ( b)carrier ( c)ASK signal.

• Let the carrier be defined as

$v_c$=$V_c$ cos⁡$w_c t$

• The corresponding ASK signal is given by the product of $v_m$ and $v_c$ as

$v_{ASK}$=$V_m$ $V_c$ cos$w_c t$when symbol is 1

=0 when symbol is 0