Multiple choice

Two 4-ray signal constellations are shown. It is given that $\phi_1$ and $\phi_2$ constitute an orthonormal basis for the two constellations. Assume that the four symbols in both the constellations are equiprobable. Let $\dfrac{N_0}{2}$ denote the power spectral density of white Gaussian noise.

The ratio of the average energy of constellation 1 to the average energy of constellation 2 is

  1. 4a2

  2. 3.5

  3. 2

  4. 8
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

By using solution we get                        Energy of constellation 1 = 14 a^2                      Energy of constellation 2 = 4 a^2                                                  Ratio = 14 a^2/4 a^2 = 3.5                      

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