Please clarify the mandatory condition on Vestigial Sideband Modulation filter?
For $(F_c,F+dF)$, it needs to be $2A-H(-F)$, when $H(F_c)=A$. See the picture below taken from (http://163.152.6.72/contents/vod/21/20121129093403/20121129093403.pdf). Here $A$ corrsponds to $1/2$ as per below figure, that is the value at $H(F_c)$. In order for the sum to become $1$, $A$ needs to $1/2$. Also, $\epsilon$ is value at any frequency in the range $(F-dF,F_c)$. So the value in $(F_C,F+dF)$ needs to be $2A-H(-F)$ so that sum $H(F) + 2A-H(-F) = 1$, as $H(F)=H(-F)$ along $F=0$.