A variable capacity rotary compressor including a housing to define therein two compression chambers having different capacities, a rotating shaft transmit ting a rotating force from a drive unit to the two compression chambers, two eccentric parts are provided on an outer surface of the rotating shaft to be placed in the two compression chambers, respectively. The apparatus also includes a perimeter that surrounds the holes such that an end user can grasp the perimeter when utilizing the apparatus. When there is a read command from the outside, the user data and error correcting code are read from the flash memory. The time synchronization also allows a time stamp to be incorporated into a message. In this way, the benefits of an averaged delay profile are achieved without the need for the additional storage and computational resources normally required by a general averaged delay profile image. In the optimum perturbation method, upon receipt of modulation symbols, channel responses are decomposed into eigenvalues and eigenvectors by Single Value Decompositin and a distortion value of the modulation symbols is estimated using the eigenvectors and the eigenvalues to minimize noise and interference power.