未来空域窗射弹数量求解方法

为解决未来空域窗射弹数量配置问题,依据未来空域窗理论最优射击密度,推导未来空域窗各瞄准点配置多发射弹情况下的毁伤概率公式,并对该公式特点进行分析。同时,基于该毁伤概率公式,提出预定毁伤概率情况下及预定毁伤概率导数情况下的射弹数量求解方法和预定射弹数量情况下的瞄准点数量求解方法。仿真实验表明,在同一条件下,通过该毁伤概率公式求得的毁伤概率与解析法求得的毁伤概率基本相同,两种情况下的射弹数量求解结果对目标的毁伤概率通过仿真验证与理论值基本一致,具有一定的可行性。     

具有末制导搜索能力武器对概略目标的区域射击方法研究

区域射击方法可以充分利用具有末制导搜索能力武器的性能特点,有效搜捕并打击未准确定位目标。现有方法采用统计模拟法分析打击过程与毁伤效能,主要针对散布服从正态分布的目标,而对于误差情况更为恶劣的概略目标缺少深入研究。区域射击方法包含武器数量计算以及瞄准点配置两个核心问题。对于服从均匀分布的概略目标,通过建立并分析毁伤概率模型,求解最优射弹散布密度函数,构建预估校正方法,计算使给定瞄准点配置对应毁伤概率达到预定要求的武器数量;以毁伤概率上界为目标,提出瞄准点配置的优化求解方法。参考国外主流装备技术参数,通过仿真计算,验证了方法的有效性与时效性,并与现有方法进行了对比,结果表明所提方法优化程度更高,并且能够使区域射击方案达到预定毁伤概率的要求。     

未来空域窗弹丸散布中心配置方法

为对付机动目标,未来空域窗射击体制应运而生。未来空域窗的设计构造,是通过对弹丸散布中心进行合理配置实现的。提出了一种新的弹丸散布中心配置方法:散布角均分法,并提出了一种修正的空域窗半径计算公式,解决现有公式计算精度不高的问题。运用仿真算例对其效果进行验证,仿真结果表明,散布角均分法改善了空域窗内的平坦性、扩大了空域窗的有效面积,适于配置未来空域窗内的弹丸散布中心。     

莱塞盖格公司激光瞄准点指示器(LASIⅡ)

已研制成LASIⅡ型激光瞄准点指示器,它在教练快速操作、由高处射击和改善夜间射击条件的训练方面是理想的。LASIⅡ使射击者能标记目标并能看到待射击弹丸的精确弹着点。     

基于最大命中概率的新型舰炮对海射击火控解算技术

根据新型舰炮初速可控的特点,提出了一种基于最大命中概率的射击诸元解算方法。初速可控舰炮增加了弹丸初速作为射击诸元要素。对视距内目标进行打击时,命中概率与弹丸初速之间存在着非线性变化关系。通过建立弹丸外弹道模型和解命中方程,进行弹道解算,并基于黄金分割的概念,采用二分法求解弹丸初速。该方法以命中概率最大为约束,可有效进行新能源舰炮武器的射击诸元解算。     

多机对多机交战中目标分配方法与目标生存概率分析

讨论了空对空多机对多机交战中,攻击机采用不同的目标分配方法对毁伤目标概率(或生存概率)的影响。文中导出了3种不同目标分配情况下,被攻击目标的生存概率算法。这3种目标分配方法,分别是目标均匀分配、随机分配和"射击 观察 射击"分配。最后算出了3种分配方法产生的目标生存概率数据对照表。     

频谱检测门限与n-out-of-K融合规则的联合优化

为了减少计算复杂度,提出联合优化检测门限λ和n-out-of-K融合规则的算法.以λ和n为参数建立目标函数,并将参数以二进制形式表示,从而把算法转化为组合优化问题.接着,采用基于样值修改的互熵优化方法渐次逼近最优的参数.仿真表明,该算法在获得与已有算法几乎相当的总错误率情况下,可有效降低平均搜索次数,且随着K的增加搜索次数增加更平缓.     

基于时域有限元的近场单站导体柱微波成像

介绍了一种在自由空间中对导体柱近场单站电磁成像的时域数值方法.提出以不均匀分布的点--离散点描述法,来代替通常采用的有限项三角级数逼近的形状函数来描述散射体.在正过程中采用时域有限元法获得其近区散射场,逆过程则通过遗传算法来寻找最优解.以不均匀分布于导体表面点的矢径的模作为优化变量.以在整个迭代过程中,目标散射场和计算散射场的误差总和与目标散射场场值绝对值之和的比值作为目标函数,使目标函数达到最小值来获得导体柱在自由空间中的电磁成像.     

机载传感器管理中信息引导雷达搜索空域研究

当前机载传感器管理中,信息引导雷达搜索的空域规划问题由信息误差和经验公式确定,雷达搜索空域较大,使信息引导失去意义.根据雷达搜索空域规划的基本原则,结合目标高斯分布的假设和目标截获概率的推导,建立信息引导雷达空域搜索模型.模型以最小化搜索空域为目标,同时满足目标截获概率和雷达的探测约束,实现对不同截获概率需求的搜索空域规划.引入带约束条件的粒子群优化算法对模型进行求解,仿真结果证明了模型的有效性,并与传统方法、遗传算法和人工鱼群算法进行了对比.     

高斯小波变换的开关电流电路实现

提出了采用开关电流电路技术实现连续高斯小波变换的方法.建立了逼近高斯母小波的优化参数模型,用非线性最小二乘法求解模型参数最优解.设计了以开关电流积分器为积木块的小波变换电路,该电路由冲激响应为母小波逼近函数及其伸缩函数的滤波器组构成.此方法对于小波变换的模拟VLSI实现具有一定的理论价值与实际意义,仿真结果表明该方法的可行性.     

Probability of error in PAM systems with intersymbol interference and additive noise

The effect of intersymbol interference and additive noise on the performance of a digital data transmission system is considered. The data sequence is assumed to be independent and equiprobable. The additive noise is independent of the signal but is not restricted to be Gaussian. A simple lower bound, an upper bound, and a simple approximation to the upper bound, on the probability of error are derived. The approximation to the upper bound is twice the lower bound; hence, either can be taken as an approximation to the actual error probability.     

Intersymbol interference and probability of error in digital systems

Intersymbol interference and additive Gaussian noise are two important sources of distortion in digital systems, and a principal goal in the analysis of such systems is the determination of the resulting probability of error. Earlier related work has sought to estimate the error probability either by calculating an approximation based upon a truncated version of the random pulse train or by obtaining an upper bound which results from consideration of the worst case intersymbol interference. In this paper a new upper bound is derived for the probability of error which is computationally simpler than the truncated pulse-train approximation and which never exceeds the worst case bound. Moreover, the new bound is applicable in a number of cases where the worst case bound cannot be used. The bound is readily evaluated and depends upon three parameters: the usual signal-to-noise ratio; the ratio of intersymbol interference power to total distortion power; and the ratio of the maximum intersymbol interference amplitude to its rms value. To illustrate the utility of the bound, it is compared with the earlier methods in three cases which are representative of the most important situations occurring in practice.     

An Upper Bound on the Error Probability for Differential Phase-Shift Keying in the Presence of Additive Gaussian White Noise and Peak-Limited Interference

A new upper bound on the error probability for differential phase-shift keyed transmission in the presence of additive Gaussian white noise (AGWN) and peak-limited interference is estimated using numerical techniques. An error probability expression is evaluated for various interference angles and the maximum value found is chosen as the upper bound. A simple approximation is presented and found to be close to the upper bound. This upper bound is shown to be a realistic bound, hence it could be useful for practical design purposes.     

Multiple-access capability of frequency-hopped spread-spectrumrevisited: an analysis of the effect of unequal power levels

A method for the evaluation of the probability of error of uncoded asynchronous frequency-hopped spread-spectrum multiple-access communications is presented. For systems with binary FSK modulation this method provides an accurate approximation and a tight upper bound to the bit error probability; for systems with M-ary FSK modulation, it provides tight upper bounds to the symbol error probability. The method enables the computationally efficient averaging of the error probability with respect to the delays, phase angles, and data streams of the different users. It relies on the integration of the product of the characteristic function of the envelope of the branch of the BFSK demodulator, which carries the desired signal, and of the derivative of the characteristic function of the envelope of the other branch. For sufficient frequency separation between the BFSK tones, the method can achieve any desirable accuracy. Moreover, the computational effort required for its evaluation grows linearly with the number of interfering users. In the M-ary case, tight upper bounds based on the union bound and the results of the binary case are derived. The method allows the effect of unequal power levels on other-user interference in FH/SSMA systems to be quantified accurately for the first time. The results indicate that the FH/SSMA systems suffer from the near-far problem, although less seriously than direct-sequence SSMA systems     

An Upper Bound on Air Interface Blocking Probability in Multiservice CDMA Networks

We propose a novel approach to derive an upper bound for the air interface blocking probability in a multiservice CDMA network with soft handoff (SHO) as a function of network load. This method requires only general assumptions made for network design and dimensioning. We obtain an approximated upper bound and compare it with the calculated values for the upper bound and with real network simulation results to show that our method with a reduced computational complexity is also accurate.     

Performance of RCPC codes with soft-decision decoding overNakagami-m fading channels

The analytical upper bounds on the pairwise error probability of rate compatible punctured convolutional (RCPC) codes, using coherent BPSK signals over slow frequency nonselective Nakagami-m fading channels with AWGN, are evaluated. With perfect channel state information (CSI) assumption, we use a direct integral with the Nakagami-m probability density function to obtain a closed form upper bound. For the case without CSI, we find an approximated upper bound for the high SNR cases and the approximation can be justified for signal to noise ratio (SNR) E _s/N₀ ≫ 1.5 dB     

Performance bounds for coded free-space optical communications through atmospheric turbulence channels

Error-control codes can help to mitigate atmospheric turbulence-induced signal fading in free-space optical communication links using intensity modulation/direct detection (IM/DD). Error performance bound analysis can yield simple analytical upper bounds or approximations to the bit-error probability. We first derive an upper bound on the pairwise codeword-error probability for transmission through channels with correlated turbulence-induced fading, which involves complicated multidimensional integration. To simplify the computations, we derive an approximate upper bound under the assumption of weak turbulence. The accuracy of this approximation under weak turbulence is verified by numerical simulation. Its invalidity when applied to strong turbulence is also shown. This simple approximate upper bound to the pairwise codeword-error probability is then applied to derive an upper bound to the bit-error probability for block codes, convolutional codes, and turbo codes for free-space optical communication through weak atmospheric turbulence channels. We also discuss the choice of interleaver length in block codes and turbo codes based on numerical evaluation of our performance bounds.     

Signal Design for Low-Error Probability in Fading Dispersive Channels

The signal design problem for FSK communication via fading dispersive channels is considered. The channel is modeled as a linear filter whose time-varying impulse response is a sample function from a zero-mean Gaussian random field of arbitrary WSSUS type. The additive noise component in the received waveforms is supposed to be a zero-mean white Gaussian random process, and maximum likelihood demodulation is assumed. The signal design procedure here adopted consists of minimizing a known upper bound on the error probability, whereas the previous similar design method by Daly intended maximizing an upper bound on the detection probability for radar-astronomy targets. Though with slightly different optimal numerical values, here, as in Daly's problem, the signal design depends on a single parameter which is a simple functional of the channel timefrequency covariance function and of the signal envelope ambiguity function. A detailed example shows how the results of this concise paper can be used to optimize signal parameters and to predict the performance loss due to nonoptimal signal envelopes.     

Error probability for reduced-state sequence estimation

The performance of ideal reduced-state sequence estimation (RSSE) (without error propagation) is known as a good approximation to the performance of real RSSE. In the literature, the minimum distance of ideal RSSE has been employed for approximating the error probability of real RSSE. However, this approximation can be very poor, even though the system has a large signal-to-noise ratio. In this work, a union upper bound on the error probability for ideal RSSE is used to approximate the true error probability. This union bound provides a better approximation than the minimum distance. A new method based on a stack algorithm and a subset-error state diagram is proposed for calculating this union bound. The stack algorithm is employed because it provides a good tradeoff between computer memory and computing time     

An efficient method for computing cell loss probability for heterogeneous bursty traffic in ATM networks

In this paper, we present an approximation for the probability of cell loss of heterogeneous bursty traffic in broadband integrated packet networks based on the asynchronous transfer mode. The sources considered here alternate between active and silent periods and are characterized by their peak and average transmission rates. The cell loss probability is obtained by considering only the number of active sources at a given time and computing the amount of traffic that exceeds the link capacity. Since the amount of buffered excess traffic is not considered in this computation, this approximation is actually an upper bound of the cell loss probability. The numerical efficiency of this bound enables it to be used as a measure based on which robust and simple resource allocation strategies can be developed for bursty sources. Comparison of this bound with the simulation results has shown that the bound is close to the actual loss probabilities especially for large burst lengths and high utilizations.