An Accurate Altimetry Method for High-Altitude Airburst Fuze Based on Two-Dimensional Joint Extension Characteristics

Considering the challenge of precise altimetry for high-altitude airburst fuzes, this paper proposes a two-dimensional joint extension characteristic altimetry method based on an improved constant false alarm rate (CFAR) detection and an accurate feature region extraction approach. First, an improved CFAR detection method with secondary protection windows is introduced to effectively mitigate the masking effect caused by conventional CFAR algorithms. The fuze-to-ground distance-based height measurement is achieved by leveraging the geometric relationship between the maximum and minimum slant distances and the impact angle. Then, to enhance altimetry accuracy under low signal-to-noise ratio (SNR) conditions, a 2D joint accurate altimetry approach is implemented by integrating Doppler-dimension extension characteristics with the conventional range-based method. The estimated impact angle is further refined using the proposed feature region extraction method. The final results demonstrate that for high-altitude airburst fuzes operating at burst altitudes between 70 m and 100 m, the proposed 2D joint altimetry algorithm provides more accurate and robust distance measurements. Under an SNR of −10 dB, the root mean square error (RMSE) is less than 2.38 m, with an error rate of approximately 3%. Notably, even at an SNR of −15 dB, the RMSE remains below 4.76 m, with an error rate not exceeding 5%, highlighting the robustness of the proposed method under low-SNR conditions.