Modulated travelling wave (MTW), $N_g=1$
This is work in progress
A modulated travelling wave with period $T$ satisfies $q(x,t+T) = q(x-s T,t)$. Equivalently, using a moving frame to freeze the wave $\xi=x-st$, it holds that $\tilde q(\xi,t+T) = \tilde q(\xi,t)$ where $\tilde q(\xi,t):=q(\xi+st,t)$. Hence, $\tilde q$ is a periodic solution to
\[\partial_t\tilde q = -sT\cdot\tilde q+F(\tilde q,p).\tag{eqMWP}\]
Stability of the MTW is determined by the spectrum of the linearized time-$T$ map associated with (eqMWP).