| The service of HF communication has experienced the development process of hand keys,analog speech,data service,digital speech throughout its history.HF communication is developing towards digitization,modularization,software implementation,networking,intellectualization,comprehensive services due to the extensive application of digital signal processing,software-defined radio,etc.In order to provide users with muti-channel services,9 different waveforms are designed based on the streaming media waveforms described in MIL-STD-188-110 C to enable digital voice services are of different transmitting bandwith and data rate.The 9 different HF digital voice waveforms are analysed and simulated.The BER performance simulated for the 9 waveforms both in AWGN channel and muti-path fading channel were given in graphs.In data service,the error-control techniques are used to improve the reliability of the communication system.The error-control technique based on ARQ+FEC may have to tansmit the data frame repeatedly when the channel is in poor condition,which will cause a massive channel resource consumption.In this thesis,fountain codes are aplied into HF communication to solve this problem.An error-control technique based on fountain codes are designed and simulated to compare the performance of the two different error-control techniques under the condition that the channel resource consumptions are the same.The hardware and software of the HF Muti-channel severices processing unit was introduced.The hardware framework based on double DSP+FPGA is given.One of the DSP is the main processer which is used to implement muti-channel services processing and management,the other one is the coprocesser which is used to implement software module related to digital voice.The FPGA is functioning as the equalizer,the decoder and several UART interfaces.Data transmission protocols,3G-ALE,data services and some other software modules are implemented based on the hardware framework. |
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