A digital signal processor for Doppler radar sensing of vital signs

摘要

A voltage waveform signal containing respiration and heartbeat signatures is low-pass filtered (0.7 Hz) for the respiration and band-pass filtered (1.0-3.0 Hz) for the heart signal. The autocorrelation function is used to calculate the rate per minute for each of these signals. To make the processor more robust, several signal processing techniques are applied. One of these techniques, a method commonly used on audio signals for formant removal, is called center clipping. Another technique is the use of a Hanning window. To reverse the distinct shape left by the Hanning window an "undo" window is applied. The processor is programmed in LabVIEW.