FMCW Radaraltimeter Signal Processing Technology Research And Realization

The radar altimeter is an active remote sensing equipment, usually installed in the flight carrier, measuring the height of the flight carrier by measuring the emission of electromagnetic waves and echo time delay. Frequency Modulated Continuous Wave radar altimeter has a low transmission power, distance blind spot, distance resolution of advantages, widely used in a variety of aerospace, aviation and military equipment.The working principle of this article is based on FMCW radar altimeter, studied the signal processing method and realization, the main work includes the following three aspects:First of all, according to two kinds of FMCW radar altimeter system analysis with the FFT processing gain effect, puts forward a method to increase the frequency of quantitative points, make up for the disadvantages of constant signal-to-noise ratio (SNR) modulation cycle system difference, and the digital signal modulation cycle control and deviation method, overcoming the modulation cycle, and partial stability of the faults.Secondly, using the classic FFT method in signal processing, quantitative restrictions of frequency problems is inevitably. In demanding higher measuring precision, frequency domain analysis method with FFT is obviously unable to meet the requirements. In order to further improve the measurement precision, this paper proposes using Chirp_Z transform instead of FFT frequency in domain analysis. This algorithm overcomes the quantitative restrictions of frequency of FFT, and improve the frequency resolution.Again,this paper analyzes the characteristics of echo spectrum of the ground targets. Due to the spectrum of the ground targets is composed of many equal magnitude spectral lines,in order to detect echo spectrum highly front, constant false alarm detection method is proposed.Finally, based on the principle of FMCW radar altimeter and algorithm, this paper designs a new kind of FMCW radar altimeter signal processing module based on FPGA, and gives the system and the main technical indexes, implements the algorithm implementation of the whole system, hardware design and embedded software design. And they are verified through the altimeter experiment and field test, verify the correctness and validity of the proposed algorithm, achieved the system design requirements, greatly improve the measurement precision.