A Note on the Noninvasive Estimation of Muscle Fiber Conduction Velocity

Average muscle action potential conduction velocity values were obtained during isometric constant-force contractions by a cross-correlation technique. To minimize the bias introduced by nondelayed activity appearing on the two myoelectric derivations, the signals were doubly differentiated. This arrangement effectively reduced the nondelayed activity and increased the accuracy of the estimate.     

The Measurement of Muscle Fiber Conduction Velocity Using a Gradient Threshold Zero-Crossing Method

The conduction velocity of myoelectric potential along muscle fiber is known to be an index of the degree of muscular fatigue or muscular disease. When detecting the myoelectric potential by means of surface electrodes, the conduction velocity must be extracted from an apparently random wave of a myoelectric signal. In this paper, a method for determining conduction velocity is proposed based upon a zero-crossing time delay measurement with reference to the derivative of a myoelectric signal. The slope value of the input signal provides an effective criterion for rejecting undesired zero crossing caused by noise. This method needs no spectral analysis nor correlation calculation. Compared to another previously reported zero-cossing approach using digital filter preprocessing, it shows a more accurate and rapid estimation of velocity.     

Direct On-Line Estimation of Muscle Fiber Conduction Velocity by Surface Electromyography

A new approach to the measurement of muscle fiber conduction velocity by surface electromyography (EMG) is developed, based upon a triple surface-electrode configuration. Unlike previously reported methods, it does not require the Fourier transformation of raw EMG data, and can be implemented on-line on a simple digital computer. Although programmed here on a PDP-11 machine, the algorithms developed are equally suited to a 16-bit microprocessor, without any need for hardware multiplication or floating-point facilities. Accurate conduction velocity estimates may be obtained every few seconds.     

A Microprocessor-Based Polarity Correlator for the On-Line Measurement of Muscle Fiber Conduction Velocity

The measurement of the average conduction velocity of action potentials along muscle fibers has important applications in muscle fatigue study and ergonomics. A cross-correlation-based method for the estimation of this velocity from surface electromyography (EMG) is presented. It is implemented on a standard low-cost 8-bit microprocessor. The use of cross correlation for such an on-line application has been made possible by the use of an efficient polarity correlation algorithm.     

一种新的频率步进信号速度估计方法

该文介绍了频率步进信号处理的基本原理,分析了相对运动速度对频率步进信号的影响,在此基础上提出了一种新的频率步进信号的速度估计方法,通过计算机仿真验证了上述方法的有效性。     

The Myoelectric Signal of Electrically Stimulated Muscle During Recruitment: An Inherent Feedback Pareter for a Closed-Loop Control Scheme

The myoelectric profile of an electrically stimulated muscle with separate and simultaneous control of firing rate and recruitment was determined. The signal consists of low amplitude, desynchronous discharge at low recruitment levels and exhibits monotonic, distinct compound action potentials at moderate to full recruitment. The myoelectric signal-force model is described by sigmoidal function when the signal is represented by its median frequency (MF), rms, or mean absolute value (MAV) at firing rates inducing just above fused force response (~28 pps). At firing rates corresponding to the maximal tetanic force of the muscle (~51 pps) the MES-force model is represented by a second-order polynomial for MF, rms, and MAV. Dynamic tracking of force induced by a sinusoidal recruitment/derecruitment of the muscle's motor unit pool at frequencies in the range of 0-1 Hz show that the MAV is independent, whereas the rms and MF are dependent on tracking frequency. The linearized MAV-force model was found superior for use as a sensorless force feedback measurement in a closed-loop control scheme aimed at restoration of regulated movement to a paralyzed limb joint.     

线性调频信号参数快速估计

线性调频(LFM)信号参数检测是对SAR对抗的一个重要问题,本文在对用Radon-Wign er变换、快速解线调和最大似然(ML)估计和分析LFM信号的基础上,给出一种消除ML估计带来旁瓣的方法,进一步提出了一种局部快速搜索的最大似然估计法,并用于LFM信号的起始频率和调频斜率等参数的估计。最后给出了三种快速算法的计算机模拟结果。     

部分样本雷达信号的参数估计

线性调频信号参数检测是SAR对抗的一个重要问题 ,其估计参数的方法有多种 ,但对于分析部分样本LFM信号而言 ,绝大多数估计方法的误差很大。在用快速相关解线调估计和分析部分样本LFM信号存有误差的基础上 ,提出了一种改进的快速相关解线调算法运用于部分样本LFM信号的起始频率和调频斜率参数的估计 ,减小了误差。最后对改进的算法进行了仿真 ,证实了改进后的有效性。     

Costas编码跳频信号自测速方法研究

Costas编码跳频信号对速度非常敏感,精确速度补偿是这种信号用来成像的关键。文中分析了速度对Costas跳频信号回波的影响,设计了一种综合测速方法,该方法将互相关测速、步进补偿和时间积累测速3种方法结合起来,逐步提高测速精度,不仅减少了计算量,满足了系统实时处理的要求,同时提高了测速精度,降低了因为速度影响引入的相位噪声。     

Some Aspects of Nonstationary Myoelectric Signal Processing

Nonstationary myoelectric signal processing is considered. A midpoint moving average estimator for the signal variance is developed. The performance of the estimator is analyzed and optimum window size criteria are derived. Comparison of the theoretical performance to experimental performance shows good agreement. The resultant estimation error is only moderately (2-3 percent) degraded from the equivalent stationary case. Finally, the developed estimator is compared to a typical squarer followed by a low-pass filter myoelectric processor. Provided that the low-pass filter has a linear phase characteristic in the passband, the two systems have essentially the same error performance.     

Limitations of Frequency Dependence as a Measure of Airway Obstruction

The purpose of this study is to develop a pulmonary model and determine the frequency response sensitivity of mechanical parameters such as impedance, dynamic compliance, and dynamic resistance as a function of individual airway properties. Computer simulations of a three compartment model of various physiological cases were used to determine lung parameters as a function of frequency, peripheral airway contribution to total airway resistance, and relative percent obstruction of the peripheral airways. Provided our present concepts of the lung are valid and adequately incorporated into the present model, our results indicate the utility of frequency dependence as a measure of airway obstruction.     

基于混频的二相编码信号参数估计

提出了一种对二相编码(BPSK)信号子脉冲宽度估计的新方法。通过获取BPSK信号的精确频率,构造相位相差π/2的正弦信号和BPSK进行混频,提取两次混频后信号的包络交叉点来对BPSK信号的相位跳变点进行估计,从而获得信号子脉冲宽度估计。仿真试验表明:在低信噪比(SNR)情况下可以较好地获得BPSK信号的子脉冲宽度估计值。     

调频步进信号的参数设计及高分辨合成算法

文章结合工程应用给出调频步进信号参数在满足通用设计原则Δf/Ba≤1的情况下,采样频率、跳频间隔之比fs/Δf为整数、非整数时对应的高分辨距离像合成算法.fs/Δf为整数时采用计算量较小的频域拼接法,非整数时采用时域滤波算法.仿真、实测数据验证了两种合成高分辨距离像算法的有效性.     

强地杂波背景下Chirp步进信号的运动补偿

Chirp子脉冲频率步进信号是一种距离高分辨率信号，目标运动对这种信号的影响很大，必须对其进行运动补偿。而现有的运动估计算法都要求具有较高的输入信杂比。在强地杂波背景下，文中采用了对消方法滤除地杂波。以满足后续的运动估计算法的要求，从而完成运动补偿，实现高距离分辨率。该文对这种方法进行了理论分析，并给出了仿真结果。     

三角调频脉冲信号参数测量方法

为精确测量三角调频脉冲信号参数,文中提出了一种联合时域、调制域测量的方法。时域分析时采用统计脉冲信号包络数值的方法估计判决门限,以实现脉冲个数、脉冲宽度等时域参数的测量。基于时域参数测量结果,调制域分析时采用相位差分法得到信号的瞬时频率曲线,进而获得准确的线性度等调制域参数。仿真结果表明,高信噪比下,该方法比现有其他方法运算量少、误差小。     

一种基于单帧数据的步进频信号运动补偿方法

介绍了频率步进雷达中多普勒效应对距离像的影响,根据频率步进雷达中常见运动补偿方法的优缺点,提出了一种仅利用单帧数据即可实现速度估计和补偿的方法,为了提高该方法的抗噪声性能,采取对算法进行迭代运算得出有效速度估计值的策略.理论分析和计算机仿真结果表明,该方法只需几次迭代(一般为3次或4次)即可得出有效速度估计值;该算法具有可行性.并兼有测速精度较高、运算量较小、抗噪声性能较强的优点.     

An Application of Signal Processing Techniques to the Study of Myoelectric Signals

This paper describes the use of power spectral density and cumulative power functions in the examination of the electromyogram (EMG). The EMG signals were obtained with surface electrodes from two muscles, the flexor pollicis brevis and the extensor digitorum, in four subjects. Each muscle was studied at two levels of contraction, both before and during fatigue. The power spectral density functions are compared, using a cumulative power difference function and the mean frequency of the spectrum, to determine differences between loading conditions in an individual muscle, before and during fatigue, between different muscles, between individuals (same muscle), and combinations of these conditions.     

用数字场强仪测量调制器应注意频率偏差

数字场强仪具有准确、耐用、方便等优点,因而得到了广泛应用,但是在实际使用中如果方法不当也会出现一些问题。 某村广播电视室新购一台ＶＳ９００数字场强仪,测得机房各频道输出电平正常,但发现严重的过调现象,怀疑场强仪有问题,但到县局校对时却正常。在这种情况下,笔者到该村电视室检查,发现该村使用的是非锁相环调制器,频率出现偏差。有些技术人员习惯于用厂家预置标准频道频率测量,未考虑调制器的频率偏差,因而所测量的值与实际电平值不同,故出现上面的现象。测量值与实际值如表１。 表中数据表明,偏差值有大有小,大的可…     

频率的精密测量方法应用

本文给出了一种利用单片机进行控制的精密测频方法，以及该方法克服测量误差的原理。并对传统的测频方法中存在的精度低的问题进行了简单分析。     

A Reliable Myoelectric Signal Detector Based on the Propagation Characteristics of Motor Unit Action Potentials

A method was proposed for detecting and rejecting motion artifacts superimposed on myoelectric (ME) signals which are used in the estimation of muscular activity, in the control of powered prostheses, and in other applications. The method is based on the propagation characteristics of motor unit action potentials derived with multiple surface electrodes placed along the muscle fibers. The contamination of artifacts was detected by the decrease of the normalized correlation coefficient calculated at the time shift corresponding to the potential propagation. The product of two correlated signals was found to be less affected by the artifacts and was a better estimate of muscular activity than the root mean square of the ME signal which is conventionally used in the applications of ME signals.