In an MCM, an optical signal is conveyed by an optical waveguide disposed on a surface of a first substrate to a first optical coupler. The first known data detector detects a location of a first known data sequence in a broadcast signal by calculating a first correlation value between the broadcast signal and a first reference known data sequence. The biasing force applied from the resilient portion is obtained by warping of a portion of the cover or a portion of the bottom portion that one of the pair of flat surfaces or an edge portion of the flat surface contacts. Further, the retainer is configured so that the holder is generally biased toward the first position. A portion of the first frontal opening can be elastically deformable such that a size of the first frontal opening is variable.