Application Of Multi-channel Multiplexing And High-speed Modem Technology

With the rapid development of communication technology and increasing needs of maritime transportation, data exchange services between ship and shore stations have become increasingly frequent.People pay more attention about transmission reliability, timeliness and confidentiality as well as high rate. Currently ship to shore communication-technology is generally backward with the problem of low rate, high error rate, a single communication style and expensive cost in the way of satellite communication. All above mentioned makes it unable to be conducive to daily ship operations.A wide range of maritime operations and limited base-construction make a great effect on the distance and reliability of maritime communication.For the development needs of the contemporary coastal port logistics, it is particularly important to select both appropriate channel coding and modulation techniques and multiplexing to improve spectrum utilization and to improve communication rate in narrowband environment is particularly important. So that, business requirements of low-cost and high-speed ship-shore communication can be met and technical support for the realization of modern efficient port management is provided.For the low efficiency problem in current ship-shore data communication service, CRC check technique is used to correct transmission errors and FEC forward check is used to improve transmission reliability. At the same time, encoded data is digitally modulated in a way of GMSK. Thus the original data can be suitable for marine communication. A higher one-way communication rate of19.2kbps is achieved by using CML CMX7143chip for GMSK modulation. Finally, two carrier singles provided by quadrature phase shift circuit pass through MC1496analog multiplier to complete the two signals quadrature modulation multiplexed. A higher rate of38.4kbps is achieved. In a word, for the current ship-shore communication error rate can be effectively reduced, communication rate is highly improved and real-time feature is strengthened for maritime business.