A method of estimating frequency of a frequency-modulation continuous-wave (FM-CW) radar level gauge under low signal-noise-ratio background

The basic principle of FM-CW radar level gauge is analyzed briefly. A method of estimating its frequency difference is proposed based on 2¹⁹-point discrete Fourier transform (DFT) and interpolation. The frequency estimation includes two steps, called coarse-estimation and fine-estimation, both of which are based on 2¹⁹-point DFT. As a result, the method is applicable to estimate a frequency under serious noise background where signal-noise-ratio (SNR) is as low as -32 dB. Simulation results show that the method is adaptive to noise and has high computational accuracy and small computation necessary, which makes it suitable for an on-line use for frequency-estimation.