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?