A novel low probability intercept radar altimeter based on FMCW and frequency hopping hybrid modulation

Among many types of modulation, the Frequency Modulated Continuous Wave (FMCW) was the most commonly used modulation technique in radar altimeter. Although FMCW radar altimeter has a good performance in range measurement for radar altimeter [1], it is easily intercepted by time-frequency analysis method such as short time Fourier transform (STFT) and Wigner-Ville Distribution (WVD) due to its simple signal form [2]. This paper proposes a novel low probability intercept (LPI) radar altimeter based on FMCW and Frequency hopping hybrid modulation, which has been not studied in the literature. FMCW ensures the high accuracy of altitude estimation while frequency hopping increases the complexity of signal form such that the proposed radar altimeter has the better property of LPI. The simulation results verify the proposed method.