Research On Key Technologies For Simulation Test Of Ultra-wideband Impulse Fuze

With the applications of ultra-wideband impulse fuzes (UWB-IF) in military fields, more efficient and accurate test methods are required in fuze production and maintenance procedures. For traditional fuzes, which are typically narrow-band, target echo simulators are usually utilized for their simulation test. Resulted from significant difference between the UWB impulse signals and narrow-band signals, the principle of UWB impulse fuzes is essentially distinct from narrow-band fuzes. The theories and technologies applied in traditional narrow-band fuze simulators are not suitable for UWB impulse fuze simulation, so new methods and technologies should be researched.First, the key technologies for simulation test of UWB-IF are introduced and analyzed. Based on the study of UWB-IF and UWB signals, the theory of target detection with UWB impulse signal is analyzed, and the effects of echo signal time jitters on target detection are revealed. Also, the nature of UWB-IF correlation accumulation is analyzed in-depth, and an important conclusion that correlation accumulation signal of UWB-IF is proportional to target echo in time and amplitude is drawn. Based on the above analysis, target echo signal calculation methods, UWB signal generation circuits, and high accurate echo signal transmission time control circuit are identified as three key technologies for simulation test of UWB-IF.Then, calculation methods for target echo signals of UWB-IFs are studied, including finite-difference time-domain (FDTD) algorithm, multidomain pseudospectral time-domain (MPSTD) algorithm, and hybrid algorithms of them. For electrically small and electrically medium problems, FDTD methods and unconditional stable method ADI-FDTD (alter direction iteration FDTD) algorithms are analyzed. An error reduced ADI-FDTD method (ER-ADI-FDTD) for Debye dispersive media is proposed by compensating truncation errors, and complete three dimensional equations are derived. Calculation results are checked and compared with traditional ADI-FDTD methods, which shows that the proposed method can maintain low error when increasing time steps. For large scale problems, parallel FDTD is studied, and a new efficient parallel ADI-FDTD method is proposed based on computation domain partition and decomposition of ADI-FDTD tridiagonal matrix of the whole domain. Compared to existing parallel ADI-FDTDs, the proposed method can provide flexible domain partition and CPU task arrangement in three dimensions, and can achieve higher efficiency by data exchanging needed only at boundary. For electrically large problems, the multi-domain pseudospectral time domain (MPSTD) method is studied and analyzed. A multidomain PSTD algorithm in Debye dispersive media is proposed and derived. Then this algorithm is applied in calculating UWB echoes from ground surface. For problem including both electrically small and large objects, the combination of FDTD and MPSTD is studied and an unconditionally stable FDTD-MPSTD hybrid algorithm is proposed. The algorithm combines ADI-FDTD and unconditionally stable MPSTD in three dimensions. Compared to existing methods, the new algorithm is completely unconditionally stable and the time step is only determined by accuracy. The algorithm is applied in mixed scale UWB antenna & ground echo simulation, and the results can provide basis for design of UWB echo signal generation circuits.Next, the design of UWB echo signal generation circuits and high accurate echo signal transmission time control circuit are studied. For generation of echos from simple targets, a UWB signal generation circuit consists of SRD (step recovery diode) and UWB BPF (band-pass filter) is proposed, experiment is performed to prove its validity. Then, in the attempt of designing a general purpose UWB signal circuit, a digitally controllable signal generation circuit based on CMOS (Complementary Metal Oxide Semiconductor) is proposed. Through accurate control of integration current and time, this circuit can get exactly the desired signal at output. Circuit simulations are performed to prove its validity. Then, a high accurate echo signal transmission time control circuit based on programmable delay chips is proposed. Large delay range and high accuracy are both achieved. Experiment results show that the delay error of the whole transmission time control circuit is below 10ps, which can meet the demands of UWB-IF simulation test.Finally, the design and implementation of UWB-IF simulation test system are presented. The design and implementation of softwares and hardwares are explained in detail. The FDTD algorithm is applied to the EM shielding black-box simulation, and effects of external EM interference are analyzed. Using the principle of perfectly matched layer, characteristics of absorbing material is simulated, and signal absorption effects on the internal simulation signals are also analyzed by simulation. To verify the reliability of the proposed simulation system, simulation test and range test are performed on same UWB-IFs. Test results are recorded and compared. By data validation and error analysis, we conclude that the proposed simulation test system is an accurate and reliable means for UWB-IF test.