Initial Nonlinear Dynamics Of The Fetal Monitor, Multi-channel Research And Fetal Heart Rate Signal Analysis

It is convenient to diagnose the healthy state of fetus in the womb bymeans of examining the heart beat rate and heart beat rate variability. Themethods of traditional fetal monitor are mostly based on linear andstatistical qualitative on primary data analog, but the multichannel fetalmonitor based on non-linear dynamical principle comes forth under theendeavor of our group. At first, the heart beat rate signals are collected bythe ultrasonic Doppler heart beat probe, then they are treated with AnalogCircuit and Digital Circuit. We can get a square wave with differentoccupancy rate. Signals are inputted into computer through PC-6360Analog-to-Digital Converter. At the same time, the womb shrink signalsare collected by the womb shrink pressure sensor, then they are dealt withdifferential magnify and are inputted into computer through PC-6360Analog-to-Digital Converter. The quickening signals are also collected bymanual switch and are inputted into computer through PC-6360Analog-to-Digital Converter. In order to collect the signals, a controlinterface of Visual Basic is completed. This control interface canaccomplish real-time display and establish a file of case, at the same time,the numerical value of instantaneous heart beat rate is sent to displaycircuit of fetal monitor, the synchronous display realized by LED. Thecontrol interface can also realize the real-time data and plots display onthree signals of the instantaneous fetus heart beat rate, womb shrink andquickening, at the same time, the recurrence data and plots are realized,which can recur the instance of the measure working. If the instantaneousheart beat rate is out of the normal scope, the lamps of alarm will be started.Then we will do some statistical time and frequency and nonlinear analysis.We hope that we could approve a uniform criterion to the doctor by theanalysis of all kinds of cases. In this paper, signals of heart beat rate are collected from 142 healthyembryo, all of them are between 36 to 41 weeks old, the sampling time isabout 20 minutes. From the results of statistical,non-linear,time and 4frequency analysis, it can be found that most of the people's heart beat ratecentralize at 145~155 times/min. It's power spectrum is a continuousspectrum with a pinnacle, which shows that the heart beat rate signal isn'tsimple noise. It can be conclude from the results that the reconstruction inthe phase space of two –dimension instantaneous heart beat rate signal isstrange. It shows primarily that the heart beat rate signal isn't simple noise,it is high dimensional chaos obeys certain dynamical law.