Research On Intermediate Frequency Sampling System And Dither Technique In HF Radar

Based on the important question in the national 863 project-HF Ground Wave Radar and ocean environment measuring technique and No. 10 five-year plan-HF Ground Wave Radar monitoring technology for long rang System (2001AA631050). researched by the Radio Propagation Lab of Wuhan University telecommunication College, this paper study the data sampling Technique and the implement way .The data sampling system is one of the most part in the signal and information processing system . In the model Radar system . we process the Radar signal through the way of digital signal processing and extract the useful information by the data sampling system . The Agreement and coherence of the amplitude and phase is not very well in the traditional Radar receiver. For solving this problem . we think digital the signal in the Intermediate Frequency (IF) band even in the Radio Frequency band and then demodulate the signal in the digital frequency domain. Data sampling is the key step in the extracting the information about the velocity of ocean surface current ,wave heights and wind field .The data system's performance is very great deal with the signal processing and the realization of vary arithmetic.Adopting Software Define Radio technology for HF GWR is the trend in the research field, the project of IF band-pass sampling after one time mixing is adopted in HF GWR .In this paper first introduce the sampling theory in the Software Define Radio (SDR) . basing on the principle of the HF GWR under the method of FM1CW analyze the requirement of HF GWR for the ADC. And then present a new design for the HF GWR data sampling system based on the DSP chip as the core platform and it develop the IF sampling circuit using dither technology .Finally analyze the experiment results.