Unwanted frequency shift in DA-converted signal

Great and thanks for the feedback. I have seen broken vectors causing high frequency spikes due to sudden changes but never checked frequency accuracy itself.

Another related case of continuity of test vectors is the case of filtered data vector.

Initially a filter produces zeros then catches up after some delay (delay pipe). In hardware filtering (not vector based input), this occurs once at the start only and can be ignored but if you produce vector then you must delete the zeros. If you do that then vector will lose continuity. The remedy is to add extra samples before filtering the vector then chopoff zeros and wrap up correctly.