Working with analytic signals h (t) = a(t)eϕ(t)+iϕ0, where a(t) and ϕ(t) are the time-varying amplitude and phase of the signal, respectively, we see that the initial phase ϕ 0 of the signal simply factors out as a constant phase in the Fourier domain and we can maximize over this initial phase by simply taking the absolute value of the scalar product of a template with a signal.