||Linear Frequency-modulated Continuous-wave (LFMCW) Radar has been widely applied in recent years for its advantages of low Probability of Interception, high range resolution, no blind range, and its simple structure. On the basis of the preliminary development of a height sensor Radar model designed by one research team, this paper aims to construct a method of using software algorithms to resolve the beat frequency signal from the relative altitude of the reflected target wave, and further, to implement the design of the range-finding system.|
Firstly, the paper introduces the work theory and the structure of FMCW Radar, elaborates on the analysis of the triangular wave FM signal, and then calculates the distance parameter. Furthermore, combining both theoretical and practical uses, the paper puts its emphasis on the problem of the height sensor not successfully calculating the proximal target (ground) signal. Through high distance detection experiments, the relevant data is gathered from the target echo, respectively in frequency domain and time domain.
Due to the problems of the LFMCW Radar structure, including transmitter signal leakage and limited hardware space of height sensor, it is hard to put the transmit-receive isolation into proper effect. The result of the measurements shows that the farther the target is positioned, the weaker the strength of the signal gradually becomes, even much lower than the near-field noise. This represents that when the height sensor system is close to the ground, it fails to resolve the altitude of the target correctly and undermines its ranging ability.
For the height sensor system improvement, the research team had developed a structure of Leaky-wave antenna array pairs, which increase the isolation between the transmitting and receiving antenna. This paper applies convolution, windows functions, FFT, and the characteristics of the square of the distance and ground targets with radar receiver power consumption to encounter the problems of signal attenuation. We establish the signal compensation by software algorithms and the simulation proves the design is valid. It not only reduces the near-field noise but also reinforces the strength of the target signal. The data is correct and the error is low. This design elevates the range-finding system to a higher level by refining the ranging accuracy.
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