  We present methods for the direct characterization of quantum dynamics (DCQD)
in which both the principal and ancilla systems undergo noisy processes. Using
a concatenated error detection code, we discriminate between located and
unlocated errors on the principal system in what amounts to filtering of
ancilla noise. The example of composite noise involving amplitude damping and
depolarizing channels is used to demonstrate the method, while we find the rate
of noise filtering is more generally dependent on code distance. Our results
indicate the accuracy of quantum process characterization can be greatly
improved while remaining within reach of current experimental capabilities.
