vitalradiopaper.pdf
wellknown property in signal processing
which states that: if the signal contains a single dominant fre
quency, then that frequency can be accurately measured by
performing a linear regression on the phase of the complex
timedomain signal [33]. Hence, we perform an additional
optimization step, whereby we filter the output of the FFT,
keeping only the peak and its two adjacent bins; this filtering
allows us to eliminate noise caused by extraneous and non
periodic movements. Then, we perform an inverse FFT to
obtain a complex timedomain signal
s
′
(
t
)
. The phase of
s
′
(
t
)
will be linear and its slope will correspond to the breathing
frequency, i.e., the breathing rate.
a human is not a point reflector, our experiments show that
a separation of 1–2 m is needed for high accuracy.
2.
Monitoring Range
Sat Jan 6 00:03:51 2018  permalink 

http://witrack.csail.mit.edu/vitalradio/content/vitalradiopaper.pdf