The present invention allows a complex digital processing engine to be tested automatically and autonomously using a minimum of memory and processing resources. In one embodiment, the invention includes an input buffer to store a digital test sequence, a digital data modulator coupled to the input buffer to generate a modulated digital sample sequence using the test sequence, a test buffer coupled to the modulator to receive and store a representation of the sample sequence, and a test buffer output to enable the test buffer contents to be compared to a reference sequence.
