Real time processing algorithm for high resolution fetal heart rate estimation

Despite the simplicity of processing, a conventional autocorrelation function (ACF) method for the precise determination of fetal heart rate (FHR) has many problems. In case of weak or noise corrupted Doppler ultrasound signal, the ACF method is very sensitive to the threshold level and data window length. It is very troublesome to extract FHR when there is a data loss. To overcome these problems, the high resolution pitch detection algorithm is adopted to estimate the FHR. The period of fetal sound is determined from the cross-correlation of two interconnected segments by its maximum value with a constant threshold. However, this method requires intensive calculations. In this paper, we suggest the fast new algorithm for real time processing.