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1968年,联邦通讯委员会(FCC)创办了会刊,旨在为移动通讯开拓更多的频谱。根据 FCC18262号记要,将超高频-电视(UHF-TV)用的806～890MHz 的70～83频道,改作地面移动通讯频道。目前,这一频段中的30MHz 频谱已用于普通和中继移动电台,而40MHz 频谱被分配给移动无线电话系统。无线电话频段限于在允许重复使用频率的“格状”系统内使用,因此,在一给定区域内能容纳大量的用户。现在两个实验系统正在芝加哥和华盛顿-巴尔太摩地区使用。余下的频段留作备份,用于未来的一些项目。目前,FCC 正在考虑把929～932MHz 频段分配给广大地区的播叫工作(PagingOperations)使用。由于允许利用这些新频段,使一些无线电制造厂得到新的交易机会,也使设计工程师们开展新的竞争。与现行的450MHZ 无线电台相比,要求这种新设备在频率-温度稳定度和较严格的误差选择方面,有成倍的改善。本文叙述这个新频段的要求、可供使用的设备类型,以及它如何影响频率控制技术。
In 1968, the Federal Communications Commission (FCC) founded the journal, aiming to open up more spectrum for mobile communications. According to FCC 18262 note, 70-83 channels of 806-890 MHz for UHF-TV are replaced with terrestrial mobile communication channels. Currently, 30MHz spectrum in this band has been used for both normal and relay mobile stations, and 40MHz spectrum is allocated to mobile radiotelephone systems. The wireless telephone band is limited to use in a “lattice” system that allows for reuse of frequencies, so that a large number of users can be accommodated in a given area. Two experimental systems are now being used in Chicago and Washington - Baltimore. The remaining bands are reserved for backup for some future projects. At present, the FCC is considering the use of 929 ~ 932MHz frequency band allocated to the broad area of paging operations (PagingOperations). By allowing these new bands to be exploited, some radio manufacturers are given new trading opportunities and new competition among design engineers. Compared with the existing 450MHZ radio station, this new device is required to have multiple improvements in terms of frequency-temperature stability and more stringent error selection. This article describes the requirements for this new band, the types of equipment available, and how it affects frequency control techniques.