Question

The advantages of DSB over SSB full carrier AM is
1. Less available channel space
2. More stable transmitter gives better reception
3. More power to transmit same signal
4. Signal is less resistant to noise

Answer 1

Correct Answer - Option 3 : More power to transmit same signal

The main advantage of DSB over SSB full carrier AM is that the DSB has more power to transmit the

same signal.

AM has three types:

• DSB-SC (double sideband suppressed carrier)
• SSB-SC (Single sideband suppressed carrier)
• VSB (Vestigial sideband)      

In AM, for a sinusoidal message signal, the total transmitted power (P_t) is given by:

\({P_t} = {P_c}\left( {1 + \frac{{{\mu ^2}}}{2}} \right)\) 

\({P_t} = {P_c} + \frac{{{P_c}{\mu ^2}}}{2}\) 

P_t = P_c + P_SB

P_c = carrier power given by:

\({P_c} = \frac{{A_C^2}}{2}\) 

μ = Modulation index

P_SB = sideband power given by:

\({P_{sb}} = \frac{{A_c^2{\mu ^2}}}{4}\) 

Efficiency (η) is defined as the ratio of the sideband power to the total power, i.e.

\(\% \eta = \frac{{{P_{SB}}}}{{{P_T}}} = \frac{{{\mu ^2}}}{{2 + {\mu ^2}}} \times 100\% \)