A system to remotely identify a person by utilizing a microwave cardiogram, where some embodiments segment a signal representing cardiac beats into segments, extract features from the segments, and perform pattern identification of the segments and features with a pre-existing data set. Other embodiments are described and claimed

McGrath, William R.

Talukder, Ashit

NASA Technical Reports Server

mu uuuu ui iiui iiui mil uui uui uui imi lull uuii uu uii mi
(12) United States Patent
McGrath et al.
(54) REMOTE, NON -CONTACTING PERSONNEL
BIO-IDENTIFICATION USING MICROWAVE
RADIATION
(75) Inventors: William R. McGrath, Monrovia, CA
(US); Ashit Talukder, Pasadena, CA
(US)
(73) Assignee: California Institute of Technology,
Pasadena, CA (US)
(*) Notice: Subject to any disclaimer, the term of this
patent is extended or adjusted under 35
U.S.C. 154(b) by 163 days.
(21) Appl. No.: 11/784,207
(22) Filed:	 Apr. 5, 2007
(65)	 Prior Publication Data
US 2007/0257787 Al	 Nov. 8, 2007
Related U.S. Application Data
(60) Provisional application No. 60/789,458, filed on Apr.
5, 2006.
(51) Int. Cl.
G05B 19100	 (2006.01)
G05B 23100	 (2006.01)
G06F 7/00	 (2006.01)
G06F 7104	 (2006.01)
G08B 29100	 (2006.01)
H04B 1/00	 (2006.01)
H04B 3100	 (2006.01)
H04Q 1/00	 (2006.01)
H04Q 9100	 (2006.01)
G08C 19100	 (2006.01)
(52) U.S. Cl . ...................... 340/5.82; 340/5.1; 340/5.21;
340/5.8; 340/5.81; 340/505
(58) Field of Classification Search ......... 340/5.1-5.21,
340/5.7, 5.8-5.82, 10.1, 825.77, 505, 5.3,
340/5.53, 825.36; 342/22, 28, 114, 115,
342/160, 162
See application file for complete search history.
(1o) Patent No.:	 US 7,889,053 B2
(45) Date of Patent:	 Feb. 15, 2011
(56) References Cited
U.S. PATENT DOCUMENTS
5,448,501 A * 9/1995 Hablov et al ............. 340/573.1
5,507,291 A * 4/1996 Stirbl et al .	 ................. 600/407
5,760,687 A * 6/1998 Cousy	 ........................ 340/554
6,031,482 A * 2/2000 Lemaitre et al .	 .............. 342/22
6,057,761 A * 5/2000 Yukl	 ....................... 340/568.1
6,307,475 B1 * 10/2001 Kelley	 ..................... 340/573.1
6,313,743 B1 * 11/2001 Abraham-Fuchs et al. .. 340/505
6,909,397 B1 * 6/2005 Greneker, III et al........ 342/173
6,927,691 132 * 8/2005 Yukl	 ....................... 340/568.1
7,135,980 132 * 11/2006 Moore et al .............. 340/573.1
7,199,749 132 * 4/2007 Greneker et al .	 .............. 342/22
2002/0138768 Al* 9/2002 Murakami et al. 	 .......... 713/202
2003/0130697 Al* 7/2003 Halperin et al ................. 607/2
2003/0135097 Al 7/2003 Wiederhold et al.
2003/0178034 Al* 9/2003 Yuki	 .......................... 128/922
(Continued)
FOREIGN PATENT DOCUMENTS
WO	 2008054490 A2	 5/2008
Primary Examiner Daniel Wu
Assistant Examiner Son M Tang
(74) Attorney, Agent, or Firm—Christie, Parker & Hale, LLP
(57) ABSTRACT
A system to remotely identify a person by utilizing a micro-
wave cardiogram, where some embodiments segment a sig-
nal representing cardiac beats into segments, extract features
from the segments, and perform pattern identification of the
segments and features with a pre-existing data set. Other
embodiments are described and claimed.
8 Claims, 1 Drawing Sheet
PRE-PROCESSING
NOISE REMOVAL
SEGMENTATION TO SEGMENT
OUT HEART BEATS
FEATURE EXTRACTION
PATTERN IDENTIFICATION
https://ntrs.nasa.gov/search.jsp?R=20110006873 2019-08-30T14:34:24+00:00Z
US 7,889,053 B2
Page 2
U.S. PATENT DOCUMENTS	 2007/0066904 At * 3/2007 Wiesmann et al. .......... 600/508
2008/0045832 At *	 2/2008 McGrath .................... 600/427
2004/0123667 At	 7/2004 McGrath
2006/0028389  At *	 2/2006 Yukl .......................... 343/853 	 * cited by examiner
U.S. Patent	 Feb.15, 2011	 US 7,889,053 B2
PRE-PROCESSING
NOISE REMOVAL
SEGMENTATION TO SEGMENT
OUT HEART BEATS
FEATURE EXTRACTION
IF
PATTERN IDENTIFICATION
FIG. 1
US 7,889,053 B2
1
REMOTE, NON -CONTACTING PERSONNEL
BIO-IDENTIFICATION USING MICROWAVE
RADIATION
BENEFIT OF PROVISIONAL APPLICATION
2
electrocardiographic waveform and an impedance-cardio-
graphic waveform, extracting features from the segments,
and performing pattern identification of the features in the
individual segments with a pre-existing data set.
5
BRIEF DESCRIPTION OF THE DRAWINGS
This application claims the benefit of U.S. Provisional
Application No. 60/789,458, filed Apr. 5, 2006, which is	 FIG. 1 illustrates an embodiment of the present invention.
herein incorporated by reference.
to	 DESCRIPTION OF EMBODIMENTS
GOVERNMENT INTEREST
In the description that follows, the scope of the term "some
The invention described herein was made in the perfor- 	 embodiments" is not to be so limited as to mean more than
mance of work under a NASA contract, and is subject to the 	 one embodiment, but rather, the scope may include one
provisions of Public Law 96-517 (35 USC 202) in which the 15 embodiment, more than one embodiment, or perhaps all
Contractor has elected to retain title. 	 embodiments.
In the past few years, it has been demonstrated that an
FIELD	 electrocardiographic (ECG) waveform may be used to iden-
tify a person, with an accuracy of about 95%. This is signifi-
Thepresent invention relates to bio -identification of people 20 cantly better than the typical accuracy of a fingerprint. How-
using microwave radiation.	 ever, an ECG usually requires at least 2 electrodes attached to
the person, which has limited its usefulness in real world
BACKGROUND	 applications. A recently developed microwave cardiogram,
disclosed in a published US patent application (publication
Accurate identification of people is critical for law enforce- 25 number 20040123667), may be employed to provide a unique
ment, as well as for many security and fraud-detection appli- 	 bio-signature for a person. This approach uses a specially
cations in the public and private sectors. Current methods	 designed microwave transceiver to form a narrow beam
employ high-resolution optical and infrared cameras or scan- 	 directed at the person of interest. The reflected microwave
ners to image the face, or read finger prints or iris patterns in	 signal contains both the electrocardiographic waveform and
the eye. These approaches work with reasonable accuracy but 30 the impedance-cardiographic (ICG) waveform of a person.
usually require direct (or extremely close) contact with the 	 This technique works over large distances, up to tens of
person to be identified: for example, by placing a hand on the	 meters, and it is very difficult to alter or disguise the ECG and
scanner plate to record fingerprints, or placing one's head
	 ICG waveforms because they are a fundamental aspect of a
against a positioning-frame to allow a lens to produce a high- 	 person's physiology. The microwave signal may penetrate
resolution image of the eye. 	 35 barriers such as walls and doors, allowing fornew capabilities
Identification based on fingerprints has been widely 	 in human identification.
deployed in recent years for security and immigration appli- 	 Embodiments use a microwave cardiogram as a bio-signa-
cations, and is even being used in some computer systems for 	 ture for an individual. The microwave cardiogram may be
user login identification. However, such systems are sensitive 	 measured over distances of several meters, and through bar-
to the presence of dirt on the fingers, often require reapplica- 40 riers such as doors and walls using a microwave signal, to
tion of the finger, and are sensitive to variants such as the 	 provide a non-contacting, remote sensing method to accu-
pressure of the finger during the fingerprint acquisition pro- 	 rately identify specific individuals.
cess. Fingerprint identification may also be fooled by using 	 Embodiments process in real time the reflected microwave
artificially gummy fingers. Facial recognition methods on the 	 signal, which contains the cardiac signature of the person,
other hand, are not necessarily limited to very-close range, 45 using digital signal processing techniques. Embodiments use
but the subject must be facing in the direction of a camera 	 machine learning-template methods to segment out each car-
since a clear, well-lit image is required. Thus it is relatively	 diac beat, and then statistically compare a few beats of the
easy to evade such systems by wearing a disguise, a face	 microwave cardiogram to a pre-existing data set in order to
mask, or tilting the head down to avoid providing a clear 	 identify the individual.
image of the face. Visual face recognition methods of course 50 A remote microwave cardiogram human identification sys-
depend critically on the quality of the image, which renders 	 tem according to some embodiments may be comprised of
such systems sensitive to range and illumination. 	 two primary subsystems: an active microwave system to
In one embodiment, the invention relates to a system for 	 remotely measure the cardiac related waveforms of an indi-
biometrically identifying a person using microwave radia- 	 vidual, and a back-end signal processing system to determine
tion, the system including at least one processor configured to 55 the identity of an individual based on his or her microwave
segment a microwave cardiac signal including cardiac beats	 reflection signal. As discussed above, the measurement of the
into segments, to extract features from the segments, and to 	 microwave cardiogram is the subject matter of a published
perform pattern identification of the segments and features 	 patent application (publication number 20040123667). An
with a pre-existing data set, where the microwave cardiac	 example of a remote cardiogram human identification system
signal is obtained from reflected microwave radiation includ-  6o according to an embodiment may be described as follows. An
ing an electrocardiographic waveform and an impedance-	 RE (Radio Frequency) oscillator generates a microwave sig-
cardiographic waveform. In another embodiment, the inven- 	 nal that is coupled to a high-directivity antenna by a circula-
tion relates to a method for biometrically identifying a person 	 tor. This antenna forms a narrow beam directed at the person
using microwave radiation, the method including segmenting 	 to be identified. A fraction of the incident signal is reflected
a microwave cardiac signal including cardiac beats into indi-  65 back from the person and picked up by the same antenna. The
vidual segments, where the microwave cardiac signal is 	 received signal is amplified, bandpass filtered, and the signal
obtained from reflected microwave radiation including an	 power level is measured with a conventional detector. This
US 7,889,053 B2
3
signal power waveform is supplied to a back-end signal pro-
cessing system for real time analysis. The microwave power
levels used are typically less than I milliwatt, and are
expected to be hundreds to thousands of times lower than the
maximum permissible dose level considered safe by the IEEE
Standards Committee on RE Exposure.
The amplitude of the reflected signal will have a relatively
large DC (Direct Current, or static) component due to the
static, or basal, impedance of the illuminated tissue, and a
small, unique time-varying component due the time-depen-
dent impedance of the tissue. The microwave beam penetrates
several millimeters of skin tissue only, and thus is affected
primarily by changes in the impedance of the dennis, which
contains blood vessels, as well as a significant amount of
extracellular fluid in the supporting matrix, There are at least
two contributions to the total time dependent impedance of
interest: the volume of blood present in the tissue, and the
concentration of ions (Na+, Cl—and others) in the extracel-
lular fluid. Both of these contributions are periodic in time,
and are driven by the mechanical and electrical action of the
heart. These cardiac-related time-dependent changes are rela-
tively very small, about 0.5% or less of the basal impedance.
However, these changes in the volume of blood and extracel-
lular ion concentration uniquely modulate the amplitude of
the reflected microwave signal to provide simultaneously the
electrocardiographic waveform and impedance cardio-
graphic waveform of the individual. This composite wave-
form may be referred to as the microwave cardiogram.
Embodiments perform signal processing to process the
microwave cardiogram signals and to determine the identity
of the individual. The identification process may comprise
two phases (sub-processes): an offline phase where a library
of microwave cardiograms of known individuals are built up,
and an on-line phase where the microwave cardiogram from
an unknown individual is preprocessed, segmented, and
matched against the library of known individuals constructed
in the off-line phase.
For some embodiments, the signal processing may include,
but is not limited to, a preprocessing noise removal step; a
segmentation procedure to segment out each beat in the car-
diac signal; a feature extraction procedure to derive salient
features from each beat; and a pattern identification proce-
dure using the segmented signals and the salient features. A
flow diagram outlining the signal processing is illustrated in
FIG. 1. For some embodiments, the boxes in FIG. 1 may
represent one or more software-controlled processes running
4
on a computer system, special purpose or programmable
modules, or perhaps combinations thereof.
Various modifications may be made to the disclosed
embodiments without departing from the scope of the inven-
5 tion as claimed below.
What is claimed is:
1. A system for biometrically identifying a person using
microwave radiation, the system comprising at least one pro-
cessor configured to segment a microwave cardiac signal
io comprising cardiac beats into segments, to extract features
from the segments, and to perform pattern identification of
the segments and features with a pre-existing data set;
wherein the microwave cardiac signal is obtained from
reflected microwave radiation comprising an electrocardio-
15 graphic waveform and an impedance-cardiographic wave-
form.
2. The system of claim 1, further comprising:
a receiver configured to receive a microwave signal, where
the microwave cardiac signal comprising the cardiac
20	 beats is derived from the received microwave signal.
3. The system of claim 2, wherein each cardiac beat is
segmented into one of the segments.
4. The system of claim 1, wherein the microwave cardiac
signal comprises information indicative of a volume of blood
25 of the person.
5. The system of claim 4, wherein the microwave cardiac
signal comprises information indicative of an extracellular
ion concentration of the person.
6. A method for biometrically identifying a person using
30 microwave radiation, the method comprising:
segmenting a microwave cardiac signal comprising cardiac
beats into individual segments, wherein the microwave
cardiac signal is obtained from reflected microwave
radiation comprising an electrocardiographic waveform
35	 and an impedance-cardiographic waveform;
extracting features from the segments; and
performing pattern identification of the features in the indi-
vidual segments with a pre-existing data set.
7. The method of claim 6, further comprising:
40 receiving a microwave signal reflected from a person; and
deriving the microwave cardiac signal from the received
microwave signal.
8. The method of claim 7, wherein each segment corre-
sponds to one of the cardiac beats.
45


Remote, non-contacting personnel bio-identification using microwave radiation

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server