engineering recuitment GATE IN Test Series 2023-24 Mock Test Communication Systems Angle Modulation Frequency Modulation
Consider an FM signal
\(x_{FM} (t) = A \cos \left[ \omega_ct + k_f \int_{-\infty}^t m(\lambda)d\lambda \right]\)
Let t1 and t2 (t2 > t1) denote the times of two adjacent zero-crossing of xFM(t)
If \(\int_{t_1}^{t_2} m(\lambda) d\lambda \approx m(t)(t_2 - t_1)\) ; t1 ≤ t ≤ t2
Then the instantaneous frequency is given as:
1
\(\left( \dfrac{\pi}{t_2 - t_1} \right)\)
2
\( \dfrac{\pi}{2(t_2 - t_1)} \)
3
2π (t2 - t1)
4
π (t2 - t1)