Design And Implementation Of HF Message Communication System Software

HF communication uses electromagnetic waves in the range of 3 to 30 MHz to transmit signals.It has the characteristics of long communication distance and strong antiinterference ability.It has a wide range of usage scenarios in marine navigation,civil aviation,military communications and other fields.Due to the changing characteristics of the ionosphere,how to choose an appropriate frequency and how to transmit data reliably has always been the focus of HF communication research.This paper is based on the research project "HF Message Communication System Development" of the research group,which aims to realize a HF communication system with functions such as link establishment,message transmission,and frequency selection.The research content of this paper is to use the existing hardware and software of the research group to design and implement the application layer software of the system.The main work is as follows:1.The existing system framework and hardware composition are analyzed,and the application layer software is divided into four modules: link establishment,message transmission,frequency management,and data storage,and the functional requirements of each module are given.2.Designed and realized the remote-control function.Aiming at the problems of reliable transmission,data encryption,integrity verification,identity authentication,etc.faced in the interaction between the application layer software and the communication controller,a secure interaction protocol is designed,which can improve the communication efficiency of messages on the Internet without affecting the upper-layer communication services.Transmission security.3.The frequency prediction function is designed and implemented.Aiming at the data of detection frequency,detection score and sunspot number accumulated by HF communication,a HF frequency prediction method based on LSTM is proposed,which regards the data as a time series,and predicts the frequency distribution of each frequency in the next day at each hour.value.The prediction results are evaluated from multiple dimensions such as the accuracy of prediction scores,the accuracy of frequency selection,and the accuracy of frequency ranking.In addition,short-term frequency prediction and REC533 frequency prediction are proposed as supplements for the case where the amount of data is small or there is no data.4.The link establishment function is designed and implemented.Two chain building methods,grouping connection and predictive connection,are proposed.In the case of cyclic monitoring on a pre-agreed frequency set,the packet connection detects several channels to be scanned by the link layer and establishes a link on the channel with the highest score.The prediction connection attempts to establish a link on several channels selected by the frequency prediction module.The success rate is high,but the time required is related to the current scanning state of the system and the accuracy of prediction.You can choose according to the actual situation to improve the success rate of chain building.5.The function of message transmission is designed and implemented.First define the message format,and then add adaptive variable speed and adaptive frequency conversion functions to the message transmission module according to the complex and changeable characteristics of HF channels.Adaptive variable speed can adjust the transmission rate in time according to the changes of the communication environment and make full use of the channel resources.The LQA frequency conversion is proposed for the temporary fluctuation of the communication environment,and the predictive frequency conversion is proposed for the large change of the communication environment.Both methods can cope with the deterioration of channel conditions and change the working frequency in time to improve the success rate of message transmission.6.The indoor test environment is built by using the HF channel simulator,and each module is tested in detail to verify the correctness of the remote control,link establishment,message transmission,frequency prediction and other schemes.