A small-size software defined cognitive radio equipment that is composed of a hardware platform and a software platform has been introduced. The hardware platform is composed of a multiband/tunable RF unit with multiple switching circuits, and the signal processing unit is composed of FPGA and CPU boards. The software platform is composed of several managers that manage spectrum sensing and reconfiguration of communication systems and is worked on the Linux. The developed cognitive radio prototype combined by hardware and software platforms senses the signal level (RSSI) over 400MHz-6GHz bands and moreover identifies the system by using reconfiguration of software packages and checks RSSI, BER, connectivity, and so on. The software packages can configure specified wireless communication systems and consist of physical layer, MAC/DLC layer, IP layer, and application layer part of the systems. This paper also describes the sensing time and reconfiguration time. ©2008 IEEE.