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The Radar Cross Section of the human heartbeat and respiration
Øyvind Aardal,PhD Student10 May 2010
Medical UWB radar at FFI overviewMedical UWB radar at FFI overview
Activities and laboratory
Calibration of UWB physiological recordings
Human heartbeat and respiration Radar Cross Section
Radar laboratory for low-clutter ycalibrated measurements
With focus on UWB, we research the use of radar for heartbeat and respiration monitoring
Ongoing research:
-Developing robust detection and processing algorithms.
-Determine the radar cross section (RCS) of heartbeats and respirationheartbeats and respiration.
Calibrated radar recordings of gphysiological motion
H ?
Frequency domain measurement modelFrequency domain measurement model
tV ( ) aH ( )
CH ( ) TH ( )
aH ( )V( ) +
2T t a C TV ( ) V ( )H ( )[H ( ) H ( )]
Frequency domain calibration routineFrequency domain calibration routine
Step 1: Remove clutter from sphere and person measurements:p p p
2T T C t a TV ( ) V ( ) V ( ) V ( )H ( )H ( )
S S S2
C t aV ( ) V ( ) V ( ) V ( )H ( )H ( )
Frequency domain calibration routineFrequency domain calibration routine
Step 2: Software gating in the fast time domain:p g g
Tv ( ) Tv̂ ( )T ( ) T ( )
Frequency domain calibration routineFrequency domain calibration routine
Step 3: Calibration in frequency domain:p q y
Tl
V̂ ( )V ( ) cal
S
V ( ) 1V̂ ( )SNR( )
With sphere and person the same range from the radar:p p g
2 T ( )| V ( ) | T
calS (
| V ( ) |)
Slow time variations at the range where gthe person is sitting
A sitting person holding his breath.
A sitting person breathing.g
Processing to separate physiological g p p y gmovement from stationary targets
calv ( )Raw signal Linear trends removed
Processing to separate physiological g p p y gmovement from stationary targets
calv̂ ( )
Further processed by bandpass filtering in slow time
Radar Cross Section (RCS) of human ( )heartbeat and respiration
2ˆ| ( ) |cal S2| v ( ) |
Remember:
( )2 Tcal
S
((
)| V ( ) |)
Radar Cross Section (RCS) of human ( )heartbeats, processed with various passbands
2ˆ| ( ) |cal S2| v ( ) |
Radar Cross Section (RCS) of human ( )respiration, processed with various passbands
2ˆ| ( ) |cal S2| v ( ) |
Radar heartbeat recordings agrees with g gECG recordings
In conclusion: The human heartbeat and respiration RCS have been found for 2-3GHz
Questions?