Research On Key Technologies Of Shortwave Digital Transmission Radio Communication System

High Frequency Data Link(HFDL)is widely used and has broad space for development in military and civil fields of wireless communications,due to its advantages of mature technology,low cost,easy to use,and long range.The receiver should equalize processing,because of the multipath effect and interference in shortwave channel.If the channel conditions were terrible,the existing equalization technology would be in poor performance.So it's important to further study equalization technology with higher performance,which is Turbo equalization.The research object of this article is the shortwave digital radio communication system that is based on HFDL,its major objective is to realize efficient HFDL signal detection,and to provide technical means to ground monitoring stations for long-distance monitoring.On the basis of building the model of HFDL shortwave digital communication system,the key research is Turbo equalization,which is the multipath channel adaptation technology on HFDL shortwave digital communication system.The specific content can be summarized as follows:First of all,this article study the content and related agreement principle of HFDL protocol.The principle of system operation process and the key module is described through the study of the characteristics of signal and transmission scheme of the system,and established the model of the shortwave digital communication system based on HFDL.Then,this article analysis the impact on characteristics of shortwave channel to the shortwave digital communication system based on HFDL,through simulated and analyzed the performance of the existing system,using the traditional shortwave channel adaptation technologies,such as LMS equalization technology.The ability to resist multipath effect of Turbo equalization is better than conventional equalization technology,because of jointing equalization and decoding process in Turbo equalization.Next,to further enhance shortwave channel adaptability of the shortwave digital communication system based on HFDL,this paper studies the working principle of Turbo equalization,and the demanding of the key modules and structures on shortwave digital communication system based on HFDL.On this basis,completed the research and theoretical derivation and simulation of the algorithms of equalizer and decoder.Finally,we'll now add Turbo equalization application to HFDL system.We can puts forward the improved and optimal design of shortwave digital radio communication system,the king of information is soft in jointing equalization decoding processing,the structure of receiver is feedback loop iterative,so this article completed improving of soft decoding algorithm instead of the original hard decision algorithm,as well as changing the kind of information in interleaving/deinterleaving and scarmb/descarmb processing,by “hard” to “soft”,to complete the optimization design.Through completing simulation of the entire signal processing,to test the performance of Turbo equalizer and the improving system,verifying the performance of the improved system improvement,by comparing and analyze with the original system.At last,we can prove that the improvement of shortwave digital radio communication system can bring obvious performance improvement,and it can possess excellent practical realizability on engineering.