The invention relates to a time-frequency-transformation-based blind extraction method of fetal
electrocardiography, which is based on the characteristic that the
time domain of an original
signal is relatively sparse. The method comprises the following steps: extracting a plurality of paths of mother-fetal mixed electrocardiosignals from different parts of mother's
abdomen, and preprocessing thecollected mixed
signal, wherein the preprocessing comprises the steps of correcting the
baseline shift of the signals, filtering off 50Hz
power frequency interference, filtering off high-
frequency noise interference such as myoelectricity and the like; selecting two paths of the mother-
fetus mixed electrocardiosignals according to the maximal
signal-to-
noise ratio and separately searching mother-fetal electrocardio
wave group positions of the two paths of mixed signals with an R-wave
positioning technology to obtain time intervals in which the mother-
fetus electrocardio in the two paths of mixed signals are relatively sparse, converting the obtained relatively sparse time intervals into a
time frequency domain by using a fuzzy function, calculating signal items and cross items in each
time frequency distribution, constructing a comparison function by using generalized Rayleigh's quotient, and finally separating fetal electrocardiosignals from the two paths of mother-fetal mixed electrocardiosignals. The method provided by the invention is tested on the basis of actual collected data, and can well separate fetal electrocardiosignals.