Joint algorithm for time of arrival estimation of S-mode baseband signals with low SNR
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摘要:
为提高接收低信噪比(SNR) S模式基带信号时广域多点定位(WAM)精确度,提出基于非相干积累的到达时间(TOA)估计联合算法。依托二次监视雷达(SSR)波束扫描驻留时间内目标应答信号具有的相关特性,提出并建立前导四脉冲匹配滤波、非相干积累的低信噪比基带脉冲信号上升沿估计方法,有效提升−15~5 dB范围低信噪比S模式基带信号TOA估计精确度。蒙特卡罗仿真结果显示,在−15~5 dB范围内的低信噪比S模式基带信号通过联合算法估计TOA的均方根误差(RMSE)优于25 ns。对于非理想S模式基带脉冲信号,信噪比低至−15 dB时,经过5个脉冲非相干积累的联合算法的TOA估计精确度达到22.245 ns,远优于WAM要求。
Abstract:To improve the wide area multilateration (WAM) accuracy when receiving S-mode baseband signals with low signal-to-noise ratio (SNR), a joint time of arrival (TOA) estimation algorithm based on non-coherent integration was proposed.According to the correlation characteristics of target reply signals during the beam scanning dwell time of the secondary surveillance radar (SSR), a low SNR baseband pulse signal rising edge estimation method with a four-pulse matched filter and amplitude squared operation and accumulation was proposed, which effectively improved the TOA estimation accuracy of S-mode baseband signals with a low SNR ranging from −15 dB to 5 dB. The Monte Carlo simulation results show that the root mean square error (RMSE) of TOA estimation by using the joint algorithm is less than 25 ns for S-mode signals with a low SNR ranging from −15 dB to 5 dB. For non-ideal S-mode baseband signals, when the SNR is as low as −15 dB, the TOA estimation accuracy of the joint algorithm after the non-coherent integration of five pulses can reach 22.245 ns, which is much better than the WAM requirement.
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表 1 −15 dB时达到25 ns以下估计精度所需运行时间
Table 1. Required operating time to achieve estimation accuracy below 25 ns at −15 dB
采样频率/MHz 最少积累信号数目 RMSE/ns 运行时间/µs 理想前导
四脉冲信号非理想前导
四脉冲信号理想前导
四脉冲信号非理想前导
四脉冲信号理想前导
四脉冲信号非理想前导
四脉冲信号40 8 13 24.475 24.140 190.0 277.0 53 6 9 23.640 24.811 232.0 363.9 80 4 6 23.433 23.563 228.1 333.1 100 3 5 24.182 22.245 211.3 241.2 -
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