A lot of techniques have been studied in order to realize high-speed wireless networks. Many wireless transmission techniques are usually validated by theoretical analysis or computer simulations assuming ideal conditions. However, actual wireless transmission performance may be degraded by errors caused by hardware limitations. Therefore, validating these techniques by hardware simulations for practical use is necessary. Furthermore, the visualization of a waveform by an oscilloscope or a spectrum analyzer is helpful for promoting research. Cognitive radio systems that can adaptively change the modulation scheme by rewriting software have attracted attention. There is a great demand for general purpose, software defined wireless transmitters and receivers. We have constructed a wireless transmission simulator by using a single inexpensive H8 microcomputer board. However, transmitting 100,000 bits takes about 60 hours, making it difficult to verify transmission performance under 10-3. We also have an SH3 microcomputer that has higher processing performance than an H8 microcomputer. In this paper, we describe the construction of a CDMA wireless transmission simulator using an SH3 microcomputer board. The signal waveform has been visualized by oscilloscope, and the BER performance has been evaluated. The transmission rate when using the SH3 microcomputer board has been shown to be 140 times or higher than that when using the H8 microcomputer board.