Design And Implementation Of HF Frequency-selecting And Link-establishing Module

Because of adaptive technology,HF communication,an ancient communication method,is refreshing.However,with the explosive growth of communication services,the previous-generation HF communication systems are unable to meet user requirements in terms of link-establishing speed,channel utilization and compatibility.Therefore,based on existing hardware devices and software drivers in the laboratory,a new generation of HF adaptive communication system is developed.The frequency-selecting module and link-establishing protocol in the system are studied mainly,the achievements of which are as follows:1.The overall architecture of the system is given.Through the communication with the client,the hardware components,software structure and each module function are determined.2.The frequency-selecting scheme is designed and implemented.In order to guarantee the performance of frequency-selection,the research starts with two aspects,long-term frequency-selection and real-time frequency-selection.It first introduces the relevant content of VOACAP,which is compiled into a DLL file that can be called by the upper computer program.And then it designs frequency-selection based on history data independently,gives the design concept and algorithm flow,and programs the frequency-selection.If the effective history channel information accumulated during the operation of the system reaches a certain scale,because of the high correlation of the working frequency at a similar time near the same date,the system will preferentially select frequency-selection based on history data.Otherwise,the system will automatically switch to frequency-selection using VOACAP software.3.A link-establishing protocol is designed and implemented.The link-establishing protocol mainly contains the functions of link quality analysis,link establishment,link removal and system synchronization.The link-establishing protocol divided into 7 states,the format of protocol data units,the normal process of working and the abnormal are presented.Finally,the design scheme is implemented with embedded program on the ARM platform.4.The testing environment to test the function and the performance of the system is built.HF communication generally working in long-distance scenarios,this paper not only carries out the indoor testing in conjunction with laboratory-developed HF transceiver and channel simulation equipment,but also has a outdoor test on actual circuit with sites and equipment provided by the project client.The test results show that both the implementation programming of the frequency-selecting module and the link establishing protocol agree with the design scheme.The frequency-selecting scheme is effective and the link-establishing protocol also has reliability and high efficiency.