Method and apparatus for generation of test bitstreams and testing of closed loop transducers

A high performance method and apparatus for testing a closed loop transducer is disclosed. A test bitstream signal is combined with a SIGMA DELTA feedback bitstream of the transducer to produce a combined bitstream which is converted to a physical feedback to the sensor of the transducer. The SIGMA DELTA bitstream output of the transducer is recorded for later analysis so as to test characteristics of the transducer. The test bitstream signal is preferably an oversampled, pulse density modulated signal. A testing arrangement is provided which is based upon the storage of short-length test patterns which are repetitively accessed to form a continuous test pattern. The test bitstream provided by the method of the invention produces very low noise and low distortion test signals where a repetitive test pattern is equivalent in length to one period of the test signal.