用小波变换的模极大值提取胎儿心率的方法

A Method of Extracting the Fetal Heart Rate by the Modulus Maxima of Wavelet Transform

对胎儿监护的主要方法是监听胎儿心率 ,而超声多普勒测量胎儿心率是一种很好的无创方法。但是 ,由于测量得到的原始信号成分非常复杂 ,干扰严重 ,从而使其对胎心率的提取造成很大困难。本文利用小波变换系数的模的平方值与信号奇异性指数之间的关系 ,从超声回波信号中提取出了胎儿的心率。由于噪声的小波变换系数随尺度的增大而减小 ,因此 ,该方法具有较高的抗干扰能力。通过模拟仿真和实际信号处理 ,证明该方法能准确地从超声多普勒信号中提取胎心率信号。

The main fetal-detecting method is used to monitor the fetal heart rate. The Doppler ultrasound is a good noninvasive way to detect the fetal heart rate. But the components of the original signal obtained from the detector are very complex and easily disturbed by many factors, which make it very difficult to abstract fetal heart rate. The fetal heart rate can be extracted from the returning signal of ultrasound by way of the connection between the modulus of the wavelet transform coefficient and the singular exponent. The wavelet transform coefficient of noise decreases with the increasing of the scale, so this method has the high ability of anti-interference. This method has been proved to be able to pick up the signal of fetal heart rate from Doppler ultrasound signal precisely by simulation and proceeding practical signals.