In an orthogonal frequency division multiplex communication system, data bits are assigned to several carriers to create frequency redundancy in the transmitted waveform. The device is configured to compare a perceived sequence input by the user to the displayed sequence, and to measure the speed of visual perception of the user. The transformer includes a primary winding, a secondary winding formed by the plasma loop, and a separate secondary winding implemented to measure the voltage along the plasma loop. Furthermore, the designer withdrawal string provides a highly visible reminder a tampon is in place and very effective means of removing the tampon. The image forming apparatus includes: an image forming unit that prints the test chart; a scanning unit that scans the test chart printed by the image forming unit and acquiring the image data; and a transmission unit that transmits the image data of the test chart scanned by the scanning unit, after changing the size of the image data corresponding to the defect.