The Design And Implementation Of Wireless Intelligent Modem

This article briefed the forest-fire protection communications system's development condition. According to Chinese forest-fire prevention network's problem, such as network integration can not be achieved, resources can not be shared and the low utilization problem, proposed using existing analog communications equipment to realize the data transmission comprehensive network plan. According to network plan's demand for wireless modem design, analyzed the digital modulation and demodulation principle and characteristics of GMSK. Based on the principle, propose the wireless modem's general design, and introduces the corresponding hardware circuit design as well system software's design process.Gaussian minimum frequency shift keying modulation methods (GMSK), theoretical research has been mature. It has the good power frequency spectrum characteristic and the superior error rate performance. Its biggest merit is that the belt external radiation is small, the power spectrum side lobe weakens quickly, to approaches the frequency the disturbance to be small. Therefore, it is suitable for the work in the VHF/UHF frequency band mobile communication system.The paper based on the forest-fire protection communications system's correspondence network demand, according to the existing VHF/UHF wave analog communications equipment's characteristic, uses the GMSK modulation system promotion forest-fire protection analog communications system. W78E52B is used as a modem control MCU chip, FX589 as GMSK modulation and demodulation chip, the design and realization of the modem. The circuit is simple, reliable and small size. It can be embedded analog VHF/UHF radio. The analog communications network will be promoted the voice and digital communication network for the forest-fire protection, the fire fighting direction and the conventional correspondence blind spot localization search and rescue communications network.