This document serves as a technical reference manual for the wideband multiple-input multipleoutput (MIMO) wireless channel sounder developed at the Wireless Research Laboratory at Brigham Young University. The development of this system is considered an "open hardware project" which means that the details of the system may be freely used by others interested in designing and building similar systems. Also, it is hoped that the open hardware methodology will lead to fruitful cooperation in improving the system and sharing ideas.