Development of Narrow-Band Digital Land Mobile Radio

概要

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A narrow-band digital land mobilr system has been developed that operates in the frequency bands of 150 and 400MHz, which are commonly used by transportation-related companies, local government, and public-sector organizations- and are therefore very congested. The number of users that can be accommodated in these bands is almost doubled by reducing the channel separation to 6.25KHz, about half that of a conventional FM system. A carrier bit rate of 9.6kbps is achieved by using π/4 shift QPSK modulation with a roll-off factor of 0.2. Laboratory and field testing showed that : ・Without propagation delay spread, a BER of 10^<-2> was obtained without using space diversity. ・With a propagation delay spread of 10μs, a BER of 6×10^<-3> was obtained without space diversity. These measurements confirmed the technical feasibility of this narrow-band system. Its widespread implementation will help mitigate the congestion in private radio systems.
社団法人電子情報通信学会の論文
2000-05-25