Broadband Shortwave Channel Simulator Key Technologies

People often need to test the performance of transmission equipment in the short-wave communication, which takes a heavy price in the actual process, and it is impossible to have the same tested condition and channel environment. In addition, it is difficult to change the channel parameters by manmade. Consequently, the development of channel simulator becomes increasingly crucial.At present, the research in short-wave channel simulator has become more sophisticated in foreign countries, but these studies focus on narrow band and low data-processing rate, and can't meet the needs of the development of broadband short-wave communication. These simulators are based on DSP implementation for narrow-band HF channel in domestic, and the parallel signal processing capabilities is relatively poor. The research goal of this paper is to achieve a reconfigurable wideband HF channel simulator, whose core processing unit is FPGA. The design and implementation of channel simulator's key modules are introduced mainly.In the second chapter, HF channel characteristics, channel model, the status and product features of the channel simulator have been introduced. Watterson channel model and ITS channel model have been analyzed, and ITS channel model was selected as the simulation model of the broadband HF channel.In the third chapter, according to needs analysis, the design has been presented, the architecture of the HF channel has been analyzed both from the hardware and software. Functions, work processes and the linkages of the various modules have been introduced in the system perspective.In the fourth chapter, the design and implementation of GUI application, middle tier program and FPGA program were introduced. The implementation of key modules were realized in the GUI application; basic function thread and PTT test thread were introduced in the middle tier program; the implementation of multipath-delay, large-scale fading, Doppler frequency spread and shift, AWGN channel were discussed in the FPGA program. In the fifth chapter, channel simulator testing methods have been given. The software and the functions of channel simulator have been tested. Those experiments show that the channel simulator can simulates multipath-delay, large-scale fading, Doppler frequency spread and shift, AWGN channel etc.The configurable HF channel simulator, which was based on the idea of Software Radio, was directly connected with the dual-radio to simulate the channel. The development of its methods, processes, and the methods of interface optimization gave some references in system development of the platform for the future.