| Radar altimeter which was used to measure the altitude of an aircraft through measuring the time elapsing between the transmission of an electromagnetic wave and its return after reflected by the ground has the characteristics of high precision and small size. Since the development of radar altimeter, it has miscellaneous application these years from navigating to military.Frequency Modulation Continuous Wave radar altimeter has the excellence of low power,low probability of being detected,small solidification, wide time-bandwidth product,high anti-active-jamming and so on.while there always are some flaws in traditional method of signal processing:altimeter measuring using beat frequency is easy and effortlessly realizing,but the large quantization error brings on the low precision;measuring using harmonic improves the signal-to-noise but the utilization ratio of frequency spectrum is too low and measuring using the leading edge of frequency spectrum requires high filter characteristics.Because of these traits,a design and implementation of all-digital radar altimeter signal processor based on FFT and constant beat-frequency is proposed in this paper, and realized through FPGA.The simulation and actual experiments on PCB proved that this design positively improved the precision and minished the size. |
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