| Shortwave communication is radio communication with an operating frequency between3MHz to30MHz. Because shortwave communication is flexible, cheap and indestroyable, it’sbeing used extensively for metrorology, military and personal radio stations. HF channel is atime-varying dispersive channel. The delay and fading of HF channel varies with frequency,hours and many other factors. Shortwave frequency band is limited. Without a system tomanage them, different radio stations tend to interfere with each other. It has practicalsignificance to put shortwave frequencies under regulation.HF frequency management system can help improve transmission quality of shortwavecommunication link through coordination of HF frequencies. All countries in the world needreliable HF frequency management system very much and they’ve also put lots of money intodeveloping it. China started late and has no practical product so far.The frequency management software introduced in this paper can be useful in shortwavecommunication and forecast, frequency assignment and node frequency coverage analysis. Itcan calculate the distribution of beacon and service frequency. It can also display coverage ofnode frequencies on a map, introducing an innovating way of data visualization. This systemcontains four main components: frequency optimization module, data visualization, databasemodule and web service module. It uses the data calculated from ITS and the data gatheredduring former rounds of execution. Based on the coverage requirements specified by users ofthis system, it considers the current sun activity level and the time of the day, and then picksthe appropriate frequency set for the shortwave stations. It puts genetic algorithm into use andcan even calculate the future coverage level for specific stations. It learns from the results offormer round of execution and will adjust accordingly, thus posseses the ability to self-learnand decide the best frequency set for the requirement being specified. |
