A Frequency Extraction Algorithm Based on Frequency Modulated Continuous Wave Ranging

Frequency modulated continuous wave ranging has a higher ranging accuracy than traditional laser ranging. The principle is to make a linear modulation to the laser emitted by the laser, and then emit laser and reflection laser interference, measuring the frequency of signals and the distance of the solution. We usually use the Fast Fourier Transform (FFT) to get the frequency of the signal. But the traditional FFT is low in frequency resolution because of the fence effect, which leads to low ranging accuracy. This paper presents a frequency correction algorithm that can be applied to laser ranging based on all- phase FFT (ap-FFT). The all-phase FFT is measured in a general manner, and the frequency estimation algorithm is used to correct the frequency results. The problem of spectrum leakage is solved, the experiment proves that the algorithm is applied to laser ranging, which is less than 1 mm in the range of 0.1 to 60 meters.