Uniform time sampling of infinite-window normal-operator frames

Under the assumptions of AIM problem 457, every sufficiently fine uniform time grid gives an unweighted frame on the infinite observation window. The Bessel hypothesis on the initial sensors and the continuous lower frame bound force the normal evolution operator to be bounded away from zero. Its specified Borel logarithm is consequently bounded. Applying the continuous upper frame bound to the logarithmic generator controls the time derivative of the observation map in $L^2$. A direct step-function approximation then supplies a uniform sampling grid and explicit frame bounds, without exponential stability.