Design Of Wireless Voice And Data Transmit System In Mapping Engineering

It develops very fast in recent years that the technology, which voice and data transmit through wireless communication channels. In domain likes electric power, irrigation works, mapping engineering ,GPS data collection, long-distance equipment stakeout and control, high danger field detect and so on, owing to nature and clime, wire transmits of voice and data is impossible in some projects. In that status, wireless data transmit will undergo a special reaction. Via wireless model, transmits of voice and data base on electromagnetic wave be called wireless voice and data transmit; Some wireless networks known like GPRS,CDMA 1X,SMS and other networks could do that work, but use these systems transmit data sometimes be delayed, or data invalidation in network jam, or network can not cover with far from the center area. Therefore, to insure voice and data transmit in real-time, and data collection, stakeout and control process in the course of nature normally, special hardware equipment and communications condition are needed.Base on require of mapping engineering ,Analog signals frequency modulation technique was adopted in our design. In the frequency interval of 144~148MHz, it was realized that voice signals were inputted through microphone and long distance. The host and subordinate machines can undertake smart communication by frequency shift keying (FSK) modulation mode. There are 256 subordinate stations in our architecture, forming a one-to-multiple point, simplex, wireless call system. The number of subordinate stations can optionally change, while the host station can selectively or wholly dial-up. Data transmits while voice signals communication in this system. The English words, Chinese characters, short messages and station number will be displayed on liquid crystal display (LCD). The emissive power is less than 0.2W and the emissive distance is than 500 m. There is no obvious distortion after signal demodulation.