Dongguan Callsun Electronic Technology Co., Ltd located in Dongguan----a famous manufacturing city in Guangdong Province, is a high-tech enterprise focusing on R&D, production and marketing of teaching wireless microphone system, which is based on IR wireless audio transmitted technology and 2.4GHz frequency hopping coding technology.Through the joint endeavor, we make a great breakthrough in IR wireless transmission distance (from the traditional 5 meters increased to 10 meters above). So our company succeeded to get the national practical new-type patent in 2007 (patent number: ZL 2007...