In binary data transmission DPSK is preferred to PSK because

From the Nicholas chart, one can determine the following quantities pertaining to a closed loop system:

Nyquist plot consider a feed back system where the OLTF is: $$G(s) = {1 \over {s\left( {2s + 1} \right)\left( {s + 1} \right)}}.$$ Determine the asymptote which the nyquist plot approaches as $$\omega \to 0.$$ Find also the range of 'k' in terms of the cross over frequency $${\omega _{PC}}$$ for stability.

In order to stabilize the system shown in fig. T_i should satisfy: