Abstract: A multiplexer receives a plurality of data streams transmitted in parallel on a time axis, and outputs partial data of each data stream every unit time in determined data stream order. A butterfly computation section at a first stage receives as second input data the partial data outputted from the multiplexer. A delay section corresponding to the butterfly computation section at the first stage receives in the data stream order the partial data outputted from the multiplexer, delays the partial data, and outputs the partial data as first input data for the butterfly computation section at the first stage.

Abstract: A head test apparatus includes a loading section that installs the head; a head operation section that causes the head installed in the loading section to execute a test access; a test section that examines the head by judging whether a test access signal obtained from the head when the test access is executed satisfies a predetermined reference; a signal output section that obtains the test access signal and outputs the obtained test access signal to an exterior of the head test apparatus; and a reference output section that outputs a reference signal which is used for taking, in the exterior of the head test apparatus, the test access signal that the signal output section outputs in synchronism with an acquisition of the head test access.

Abstract: A magnetic head testing apparatus includes reference information storing unit for holding a predetermined reference sampling period and a number of reference samplings, sampling unit for sampling reproduced data read a plurality of times from a magnetic medium in the reference sampling period, sampling number acquiring unit for acquiring a sampling number of measured data from a reproduced data base on a sampling result, sampling number ratio calculating unit for calculating a ratio of the sampling number of the measured data and the number of reference samplings, sampling data re-acquiring unit for changing the sampling period of the measured data depending on the calculated ratio and re-acquiring the sampling data and a measured data overlap-displaying unit for overlap-display of the sampling data re-acquired from the measured data a plurality of times.

Abstract: A magnetic head testing apparatus includes reference information storing means for holding a predetermined reference sampling period and a number of reference samplings, sampling means for sampling reproduced data read a plurality of times from a magnetic medium in the reference sampling period, sampling number acquiring means for acquiring a sampling number of measured data from a reproduced data base on a sampling result, sampling number radio calculating means for calculating a ratio of the sampling number of the measured data and the number of reference samplings, sampling data re-acquiring means for changing the sampling period of the measured data depending on the calculated ratio and re-acquiring the sampling data and a measured data overlap-displaying means for overlap-display of the sampling data re-acquired from the measured data a plurality of times.