Abstract - A digital signal processor for Doppler radar sensing
of vital signs is described. 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.
Keywords - DSP, Doppler, heart rate, respiration rate,
autocorrelation, center clipping, Hanning window.