Interference Than The Phase Method Instantaneous Measured Frequency

Radar system plays an important role in modern electronic warfare.With the development of science and technology,frecquence agile technology is widely used on modern radar system. Whether the radar system can collect its frequences' change effectively or not when its pulse changes quickly has become a crucial factor in having the priority in modern war .Therefore, the instantaneous frequency measurement technology has a important research value in the modern electronic warfare.A classic Frequency Measurement method is called interferometer phase-comparison:the main idea of this method is to transform the signal's frequency to phase and then calculate its frequency through the measurement of the phase's range change.Having good transient performance,this kind of mothod has been widely used in practice.However ,its bottle-neck due to it can't supply enough precision in measurement.The digital signal processing parts of this paper has put forwards some concrete resolves from two aspect to enhance its precision. First:some improvements of the traditional filter method can avoid the errors caused by transitting two frequences betwwen the same group of datas and enhance its measure precision. Second: to avoid the common imbalance of the two-channal orthogonal IQ signal .this paper use CORDIC algorithm to get the signal's phase. The result shows this algorithm can have a good performance in balance the- two-channal orthogonal IQ signal,and increase the accuracy of the measurement greatly.This paper on the basis of research on instantaneous frequency measurement with practical projects,identified the resolution systematicly;digital signal processing parts have applied modular design and FPGA technology;analysis the effectivity of adopting the CORDIR algorithm's good performance in reducing the imbalance of the orthogonal two-channal IQ signal;analysis the frequency measure precision and time of the whole system and identified the feasibility of the resolve.The design of the digital circuit has been given at last.