as) United States
`a2) Patent Application Publication 0) Pub. No.: US 2004/0220488 Al
`(43) Pub. Date: Nov.4, 2004
`
`Vyshedskiy etal.
`
`US 20040220488A1
`
`(54) METHOD AND APPARATUS FOR
`PHYSIOLOGICAL DATA ACQUISITION VIA
`SOUND INPUT PORT OF COMPUTING
`DEVICE
`
`(76)
`
`Inventors: Andrey Vyshedskiy, Boston, MA (US);
`William Kania, Westborough, MA
`(US); Raymond Murphy, Wellesley,
`MA(US)
`
`Correspondence Address:
`Andrey Vyshedskiy
`Suite 4990
`1153 Centre St.
`Boston, MA 02130 (US)
`
`(21) Appl. No.:
`
`10/694,910
`
`(22)
`
`Filed:
`
`Oct. 29, 2003
`
`Related U.S. Application Data
`
`(60) Provisional application No. 60/466,242, filed on Apr.
`29, 2003.
`
`Publication Classification
`
`(51) Ute C17 ccecccccscssecsenseee A61B 5/04; AGIB 5/02
`
`(52) U.S. C1. ee ececeeceteeseenee 600/513; 600/528; 381/67
`
`(57)
`
`ABSTRACT
`
`A sound input port is ubiquitously present in many types of
`devices including PCs, PDAs, cell phones, land line phones,
`and voice recorders thereafter referred to as “computing
`devices”. A sound port allows data input into a computing
`device for further computation, visualization and data trans-
`mission. Unfortunately most computing devices only allow
`one channel of data acquisition via the sound port. Further,
`the acquired data are highpassfiltered. A method of extend-
`ing the signal range to very low frequencies and recording
`a plurality of data channels via a single sound port
`is
`disclosed here. This method uses amplitude modulation of
`carrier frequencies to create a composite signal. The com-
`posite signal is then transmitted into the computing device
`either via wire or wirelessly. Demodulation occurs in the
`computing device. In the preferred embodiment the audio
`signal from an electronic stethoscope and the amplitude
`modulated EKGare transmitted into a computer via a single
`microphoneport. In an alternative embodiment physiologi-
`cal data from multiple sensors are transmitted into a com-
`puter via a single microphone port.
`
`204
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`206
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`207
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`201
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`203
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`203
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`203
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`C)
`
`Signal
`Conditioning
`and
`Modulation
`
`Circuit
`
`Microphone
`Input of
`Computing
`Device
`
`205
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`APPLE 1008
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`APPLE 1008
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`1
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`

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`Patent Application Publication Nov. 4, 2004 Sheet 1 of 8
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`US 2004/0220488 Al
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`107
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`108
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`109
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`110
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`111
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`2
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`Cai
`Frequency
`1
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`Carr
`Frequency
`
`Amplifier
`2
`
`Lowpass
`Filter 2
`
`Corr
`Frequency
`N
`
`Amplifier
`N
`
`Lowpass
`Filter N
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`Figure 1A.
`
`Amplifier
`1
`
`Lowpass
`Filter 1
`
`0
`
`102
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`103
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`104
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`105
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`106
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`Analog
`Multiplier 1
`
`Analog
`Multiplier 2
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`Analog
`Multiplier N
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`Summing
`Amplifier
`
`Composite
`Signal Output
`
`2
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`

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`Patent Application Publication Nov. 4, 2004 Sheet 2 of 8
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`US 2004/0220488 Al
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`Figure 1B
`
`121
`
`Composite
`Signal from
`microphone
`
`port
`
`Carrier
`Digital
`Carrier
`Digital
`Carrier
`Digital
`
`
`Bandpass||Frequency Bandpass||Frequency Bandpass|}Frequency
`Filter 1
`1
`Filter 2
`2
`Filter N
`N
`
`
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`123
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`124
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`125
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`126
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`127
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`122
`
`Digital
`Multiplier
`
`Digital
`Multiplier
`
`Digital
`Multiplier
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`128
`
`129
`
`
`130 [OutputN
`131 )
`132
`
`
`
`Output 2
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`Output N
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`Output1
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`3
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`

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`Patent Application Publication Nov. 4, 2004 Sheet 3 of 8
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`US 2004/0220488 Al
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`Figure 2.
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`201
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`203
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`203
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`204
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`206
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`207
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`503
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`©)
`
`:
`Signal
`Conditioning
`and
`Modulation
`
`Circuit
`
`:
`Microphone
`Input of
`Computing
`Device
`
`205
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`4
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`Patent Application Publication Nov. 4, 2004 Sheet 4 of 8
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`US 2004/0220488 Al
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`Figure 3
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`301
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`302
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`304
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`305
`
`306
`
`307
`
`Carrier
`Frequency
`
`EKGInput
`
`EKG
`Amplifier
`
`Analog
`Multiplier
`
`Audio Input
`
`Audio
`Amplifier
`
`308
`
`309
`
`LowpassFilter
`
`310
`
`Summing
`Amplifier
`
`Composite
`Signal Output
`
`5
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`Patent Application Publication Nov. 4, 2004 Sheet 5 of 8
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`US 2004/0220488 Al
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`Figure 4.
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`404
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`402
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`401
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`403
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`6
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`Patent Application Publication Nov. 4, 2004 Sheet 6 of 8
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`US 2004/0220488 Al
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`Figure 5.
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`501
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`:
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`502
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`TES 17500 ‘seconds_18.0001600. 16500 17.000 18:
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`7
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`Patent Application Publication Nov. 4, 2004 Sheet 7 of 8
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`Figure 6.
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`8
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`Patent Application Publication Nov. 4, 2004 Sheet 8 of 8
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`Figure 7.
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`US 2004/0220488 Al
`
`Nov.4, 2004
`
`METHOD AND APPARATUS FOR
`PHYSIOLOGICAL DATA ACQUISITION VIA
`SOUND INPUT PORT OF COMPUTING DEVICE
`
`[0001] Priority is claimed by provisional application No.
`60/466,242 filed on Apr. 29, 2003 entitled Method of data
`acquisition via microphone port of a computer.
`
`FIELD OF THE INVENTION
`
`[0002] The invention relates to systems used for physi-
`ological data acquisition. It also relates to diagnostic sys-
`tems.
`
`BACKGROUND OF THE INVENTION
`
`[0003] A-sound input port is ubiquitously present in many
`types of devices including PCs, PDAs,cell phones,land line
`phones, voice recorders, etc., hereafter referred to as com-
`puting devices. This sound input port can be primarily of 3
`types: 1) a microphoneport, 2) a line port, and 3) a wireless
`port (e.g. Bluetooth Headset). These ports are similar in their
`frequency characteristics with two notable differences. A
`line port is designed for stronger “line-level” signals with
`peak-to-peak amplitude of approximately 10V. Furthermore
`a line port does not supply bias DC voltage. A microphone
`port is designed to receive smaller signals with peak-to-peak
`amplitude of approximately 100 mV. In addition, a micro-
`phone port normally provides a bias DC voltage. Micro-
`phones lacking their own power supply rely on bias DC
`voltage for their power source. The invention disclosed
`herein can be used with either line, microphone, or wireless
`ports. Consequently, all sound input ports are hereafter
`referred to as “a microphone port” or “a sound port”.
`
`[0004] A microphone port allows analog data input into
`computing devices for further computation, visualization
`and data transmission. Unfortunately most computing
`devices only allow one channel of data acquisition via a
`microphone port. Standard multiplexing methods for trans-
`mitting a plurality of data channels via a single channel do
`not work since the microphone port has a hardware lowpass
`filter. The invention disclosed herein does not use a multi-
`plexing method. Rather, the invention uses amplitude modu-
`lation of a plurality of data channels to transmit the com-
`posite signal into a microphoneport of a computing device.
`All signals can be demodulated in the computing device
`with no loss of data.
`
`[0005] Devices for concurrent recording of two or more
`channels of physiological data are well known. US. Pat.
`Nos. 5,165,417, 5,844,997, 6,139,505, 6,394,967 to Ray-
`mond Murphy, the inventor herein, disclose multichannel
`sound recording system based on a multichannel A/D board.
`
`[0006] U.S. Pat. No. 4,053,951, to Hudspeth,et al. entitled
`Data acquisition, storage and display system discloses the
`device for medical data acquisition including temperature,
`respiration rate and pulse rate are measured andstored in an
`acquisition unit incorporating a circulating register for stor-
`ing data covering many patients.
`
`[0007] U.S. Pat. No. 5,701,904 to Simmons,et al., entitled
`Telemedicine instrumentation pack discloses a portable
`medical diagnostic apparatus which includes three types of
`data-gathering instruments: (1) visual instruments (eg, oto-
`scope, ophthalmoscope, rhino-laryngoscope, macro lens and
`fundus camera); (2) an audio instrument (eg, electronic
`
`stethoscope); and (3) data-gathering instruments (eg, pulse
`oximeter and ECG monitor). The signals are transmitted to
`a remote site for analysis by medical personnel.
`
`[0008] Although these devices fulfill the purpose of mul-
`tichannel data acquisition they all rely on special data
`acquisition hardware which makes them expensive and
`cumbersome. Recording two or more channels of data via
`the ubiquitous microphone port is advantageous for many
`reasons. The multichannel sound recording system disclosed
`herein is based on the existing microphone port and conse-
`quently does not require an addition of data acquisition
`hardware resulting in a cheaper and less cumbersomesys-
`tem.
`
`[0009] Further, a highpass filter on the input of the micro-
`phoneport prevents recording of data below 20 Hz. Many
`physiological signals below 20 Hzare of great importance,
`for example EKG and seismocardiogram. The invention
`disclosed herein uses amplitude modulation of a carrier
`frequency. The particular carrier frequencies are chosen
`from frequency range that is unaffected by the microphone
`port hardwarefilters. This allows recording of low frequency
`signals, that is signals below 20 Hz, via the microphone port
`of the computing device.
`
`BRIEF SUMMARY OF THE INVENTION
`
`[0010] The invention disclosed herein extends the record-
`ing frequency range of a microphone port
`to very low
`frequencies and allows a plurality of data channels to be
`transmitted into a computing device via the microphoneport
`using multiple frequency bands. Briefly, amplitude modu-
`lation occurs in the hardware using a set of carrier frequen-
`cies. The resulting amplitude modulated signals are summed
`into a composite signal which is transmitted into the micro-
`phoneport of the computing device. Demodulation occurs in
`the software. The composite signal can be transmitted to the
`computing device by wires, by wireless data communica-
`tions, by a network of computing devices or by a combina-
`tion of these means.
`
`[0011] The stethoscopes are widely used by medical per-
`sonnel to listen to body sounds. Unfortunately the stetho-
`scopes do not allow recording or visualization of sounds, nor
`do they allow to easily relate heart sounds to the events of
`the heart cycle apparent on the EKG.
`In the preferred
`embodiment, referred thereafter as “EKG Stethoscope”, the
`disclosed method is used to simultaneously transmit the
`audio signal from an electronic stethoscope and the corre-
`sponding electrical EKG signal into a computing device via
`the microphone port of the computing device.
`In other
`words, the EKG Stethoscope allows the medical practitioner
`to perform auscultation and obtain electrocardiogram at the
`same time. The recording/visualization device could be a
`personal computer, a PDA, a mobile phone, a land line
`phoneor a voice recorder. The data can be transmitted via
`wire or wirelessly (for example using Bluetooth technol-
`ogy).
`
`[0012] The EKG Stethoscope has the following advan-
`tages:
`[0013] A phonocardiogram can be visualized simul-
`taneously with an electrocardiogram.
`[0014] Auscultation of heart soundsis greatly facili-
`tated by knowing the event of the heart cycle visu-
`alized on the EKG.
`
`10
`
`10
`
`

`

`US 2004/0220488 Al
`
`Nov.4, 2004
`
`is computer based, heart
`that
`[0015] Automatic,
`sound analysis is facilitated by identification of
`events on the electrocardiogram.
`
`106. The composite signal can be then transmitted into the
`microphone port of the computing device via wire or wire-
`lessly.
`
`[0016] The EKG Stethoscope system uses the fact that
`neither the EKG nor the audio signal requires the full
`bandwidth of the microphoneport (which is 20 Hz to 44,100
`Hz). Normally the EKG signal is between 0.5 Hz and 300
`Hz, and body sounds are between 20 Hz and 2000 Hz.
`Therefore, there is sufficient bandwidth to transmit both
`EKGand sound into the microphoneport of the computing
`device.
`
`In an alternative embodiment physiological data
`[0017]
`from multiple sensors, such as acoustic pick-up sensors, are
`transmitted into the computing device via a single micro-
`phoneport. Similarly, body soundsare limited in bandwidth
`to 2000 Hz. Therefore, theoretically, up to 11 channels can
`be modulated and concurrently transmitted into a micro-
`phone port with bandwidth of 44,000 Hz.
`
`BRIEF DESCRIPTION OF THE DRAWING
`
`[0018] FIG. 1A is a flow chart of a system for implement-
`ing data acquisition from a plurality of data channels via a
`single microphone port of a computing device;
`
`[0019] FIG. 1Bis a flow chart of a system for implement-
`ing demodulation of a composite signal of FIG. 1A;
`
`[0020] FIG. 2 is a block diagram of a system for imple-
`menting a preferred embodimentof the present invention;
`
`[0021] FIG. 3 is a flow chart of the steps performed in
`Signal Conditioning and Modulation Circuit of FIG.2.
`
`[0022] FIG. 4 shows overall design of the EKG Stetho-
`scope with EKG electrodes embeddedinto the chest piece as
`viewed from the bottom.
`
`FIG.5 is a data plot of the composite signal (top)
`[0023]
`separated by filtering into modulated EKG (middle) and
`audio signal (bottom).
`
`[0024] FIG. 6 is a data plot of the amplitude modulated
`EKG(top), the EKG multiplied by carrier signal (middle)
`and the EKG lowpassfiltered with a cutoff frequency equal
`to 25 Hz resulting in a clean EKGsignal (bottom).
`
`FIG.7 is a data plot of the composite signal (top)
`[0025]
`and the recovered signals. The EKG signal is shown in the
`middle and heart sound is shown in the bottom.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`[0026] FIG. 1A isa flow chart of a system for implement-
`ing data acquisition from a plurality of data channels via a
`microphone port of a computing device. Input 1101is first
`amplified by an Amplifier 102 and then is filtered by a
`LowpassFilter 103 with cutoff frequency of fu... Further
`the resulting signal is multiplied by the carrier frequency
`fe, 207 in an Analog Multiplier 104. The resulting modu-
`lated input 1 signal is moved up on the frequency scale to
`occupy the interval from fy.ierfeutore 10 fearriertloutot
`
`[0027] A plurality of inputs from Input 2108 to Input N
`110 can be modulated by the corresponding carrier frequen-
`cies 109, 111. All modulated signals are summed by a
`Summing Amplifier 105 to derive a composite signal output
`
`[0028] Consider an 8 channel data acquisition system
`transmitting data into a standard computer sound card with
`sampling rate of 44,100 Hz. Each input channel of the 8
`channel data acquisition system records data from a sensor
`with a bandwidth of 0 Hz to 1,000 Hz. All eight lowpass
`filters can be chosen to have cutoff frequency equal to 1,000
`Hz. Eight carrier frequencies can be chosen as follows:
`f1=2,500 Hz, f2=5,000 Hz, f3=7.500 Hz, f4=10,000 Hz,
`f5=12,500 Hz, {6=15,000 Hz, {7=17,500 Hz, £8=20,000 Hz.
`Amplitude modulation allows to distribute 8 data channels
`over the frequency range of the sound card. The carrier f1
`modulated by input 1 occupies interval from 1,500 Hz to
`3,500 Hz,
`the carrier f2 modulated by input 2 occupies
`interval from 4,000 Hz to 6,000 Hz, ... , the carrier £8
`modulated by input 8 occupies interval from 19,000 Hz to
`21,000 Hz. The summing amplifier then sums eight ampli-
`tude modulated carrier frequencies into a composite signal.
`
`[0029] The composite signal is then transmitted into the
`microphone port of the computing device via wire or wire-
`lessly.
`
`Inside the computing device the composite signal is
`[0030]
`demodulated. As long as intervals occupied by modulated
`signals in the frequency domain are separated,it is possible
`to recover original signals with no loss. The demodulation
`flow chart is shown in FIG. 11B. The composite signal 121
`is digitized by the computing device sound card. A digital
`bandpassfilter 1122 is used to separate the frequency band
`around the carrier frequency 1123 from f,,,.ic,-foutor to
`sarrierttoutore Lhe resulting signal is multiplied by a digitally
`generated carrier frequency 1123 in a digital multiplier 128.
`The resulting signal is filtered by a Digital Lowpass Filter
`129. As long as the carrier frequency 123 is equal to the
`carrier frequency 107 of FIG. 1A,
`the resulting Output
`signal 1130 is equal to the Input 1101 of FIG. 1A.
`
`[0031] Similarly, the composite signal 121 can be broken
`downinto a plurality of frequency bandsby digital bandpass
`filters 2124 through N 126. Each bandis multiplied by the
`corresponding carrier frequency 125 through 127 and con-
`sequently filtered with lowpass
`filters. The
`resulting
`demodulated output signals 2131 through N 132 are indis-
`tinguishable from the corresponding inputs 108 through 110.
`These outputs can now berecorded, visualized, and ana-
`lyzed by the computing device.
`
`Inthe example of the eight channel data acquisition
`[0032]
`system mentioned abovethe digital bandpassfilter 1 can be
`a Hamming bandpassfilter with 512 taps and pass band from
`1,500 Hz to 3,500 Hz; the digital bandpassfilter 2 can be a
`Hamming bandpassfilter with 512 taps and pass band from
`4,000 Hz to 6,000 Hz; ... ; the digital bandpassfilter 8 can
`be a Hamming Window bandpassfilter with 512 taps and
`pass band from 19,000 Hz to 21,000 Hz. Further each
`channel is digitally multiplied by the corresponding carrier
`frequency. The output of the digital bandpass filter 1 is
`multiplied by the carrier frequency 1 equal to 2,500 Hz; the
`output of the digital bandpass filter 2 is multiplied by the
`carrier frequency 2 equal to 5,000 Hz, ... ; the output of the
`digital bandpass filter 8 is multiplied by the carrier fre-
`quency 8 equal to 20,000 Hz. Further the result of multi-
`plication is filtered by a digital lowpass filter. All digital
`
`11
`
`11
`
`

`

`US 2004/0220488 Al
`
`Nov.4, 2004
`
`lowpass filters can be Hamming Window lowpass filters
`with 512 taps and pass band between 0 Hz and 1000 Hz.
`
`[0033] FIG. 2 shows a block diagram of a system for
`implementing a preferred embodimentof the present inven-
`tion, the EKG Stethoscope. The chest piece 201 picks up an
`acoustic signal from the body, converts the acoustic energy
`into an electrical signal and than transmits the signal via wire
`or wirelessly 204 into a Signal Conditioning and Modulation
`Box 206. Further the electrocardiographic signal from the
`patient’s skin is picked up by EKG electrodes 203 and
`transmitted via wire or wirelessly 205 into a Signal Condi-
`tioning and Modulation Box 206. The composite signal from
`the Signal Conditioning and Modulation Box 206 is trans-
`mitted to the MicrophonePort of the computing device 207.
`
`[0034] FIG. 3 describes the flow chart of the steps per-
`formed in the Signal Conditioning and Modulation Box 206
`of FIG. 2. The EKG input 301 from EKG electrodes placed
`on patient’s skin is amplified by a standard EKG amplifier
`302 with a gain of 1 V/mV. Furtherit is filtered by a bandpass
`filter 0.5 to 120 Hz and 60 Hz notch filter (-23 dB). The
`resulting amplified and filtered EKG is multiplied by the
`carrier signal 307 with frequency 3,000 Hz in the Analog
`Multiplier 304. Note that
`the resulting modulated EKG
`signal is located in the frequency band centered around the
`carrier frequency, that is between 2,700 Hz and 3,300 Hz.
`
`[0035] The audio input 308 from sound pickup placed on
`the patient’s skin is amplified by the Audio Amplifier 309
`and filtered by a LowpassFilter 310 with a cutoff frequency
`of 2,000 Hz. The modulated EKG signal is then summed
`with the amplified and filtered audio signal by the Summing
`amplifier 305. The resulting composite signal output 306 is
`transmitted via wire or wirelessly into the computing device.
`
`[0036] FIG. 4 shows the overall design of the EKG
`Stethoscope with three EKG electrodes 403 mounted on the
`chest piece 401 around the diaphragm 402. The physician
`can move chest piece around the chest to collect data at
`different sites. The suitable EKG electrodes can be made of
`electroconductive material and have an area of 1 cm®. The
`sound amplification can be either electronic via wire or
`acoustic via tubing 404. The suitable microphone for the
`electronic sound amplification can be omnidirectional elec-
`tret microphone embedded into the chest piece. The EKG
`Stethoscope allows a medical practitioner to avoid applica-
`tion of separate EKG electrodes. The result is a faster and
`less cumbersome procedure.
`
`[0037] The computing device of the EKG Stethoscope can
`be a PDA such as Compaq iPAQ5450 Pocket PC. The
`composite signal 306 of FIG.3 is transmitted to the PDA’s
`microphoneinput port. The transmission can be via the wire
`connected to an external 3.5 mm microphonejack or wire-
`lessly via bluetooth headset protocol. No modification or
`special hardware is required with iPAQ5450. The PDA can
`be programmed to conduct the demodulation of the com-
`posite signal. The PDA can display the results of demodu-
`lation on its screen and store the data for later retrieval/
`transfer. Also, the PDA can be programmed to perform the
`automatic analysis of the EKG andacoustic signals.
`
`Inside the computing device the composite signal
`[0038]
`306 of FIG.3 is demodulated into an EKG and audio signals
`for further recording, visualization, and analysis. FIG. 5 is
`a data plot of a composite signal 501 recorded from a
`
`subject. The composite signal 501 is first filtered by a
`lowpassfilter with cutoff frequency of 2000 Hz. The result-
`ing signal is a pure audio signal 503, FIG. 5. Further, the
`composite signal 501 is filtered by a bandpass filter with
`cutoff frequencies of 2700 Hz and 3300 Hz. The resulting
`signal is the modulated EKG signal 502.
`
`[0039] FIG. 6 shows the process of demodulation of the
`EKGsignal 502 of FIG. 5. The modulated EKG signal 601
`is multiplied by the carrier frequency. The result of digital
`multiplication is the signal marked 602. Further, the signal
`602 is filtered by a lowpassfilter with a cutoff frequency of
`25 Hz. The resulting signal is a clean EKG signal 603.
`
`[0040] FIG. 7 is a data plot of the composite signal 701,
`same as 501 of FIG.5, and the demodulated EKG 702, same
`as 603 of FIG.6, and sound signal 703, same as 503 of FIG.
`5, shown in the stack mode.
`
`Weclaim:
`1. A method of wired or wireless physiological data
`acquisition via sound input port of a computing device using
`amplitude modulation of data with one or more carrier
`frequencies.
`2. The computing device of claim 1 selected from a group
`consisting of a desktop computer, a notebook,a tablet PC, a
`PDA,a mobile phone, a land line phone, a tape recorder, and
`a digital voice recorder.
`3. The computing device of claim 1 transmitting data to a
`secondary computing device, such as a servereither via wire
`or wirelessly.
`4. The data of claim 1 including a plurality of channels
`modulated by multiple carrier frequencies.
`5. The carrier frequencies of claim 1 distributed over the
`permissible sound port frequency range in such a manner
`that neither frequency band overlaps with any other fre-
`quency band.
`6. The carrier frequencies of claim 1 supplied by the audio
`output of the computing device or generated by circuitry
`outside of the computing device.
`7. The sound input port of claim 1 wherein sound input
`port is a microphoneport, a line port, or the wireless sound
`port of a computing device.
`8. The wireless sound port of claim 7 wherein wireless
`protocol selected from a group consisting of a bluetooth
`protocol and a Wi-Fi protocol.
`9. The bluetooth protocol of claim 8 wherein a headset
`profile is used to transmit data to and from the computing
`device.
`
`10. The physiological data acquisition system using said
`amplitude modulation method of claim 1 to transmit mul-
`tiple cannels of physiological data to said microphoneport
`of said computing device.
`11. The computing device of claim 1 wherein the demodu-
`lation of the composite signal by software occurs in real
`time.
`
`12. The EKG Stethoscope using said amplitude modula-
`tion method of claim 1 comprised of:
`
`(a) a stethoscope,
`
`(b) an electrocardiograph, and
`
`(c) EKG electrodes,
`
`whereby a medical practitioner is enabled perform
`simultaneous auscultation and electrocardiography.
`
`12
`
`12
`
`

`

`US 2004/0220488 Al
`
`Nov.4, 2004
`
`13. The EKG Stethoscope of claim 12 wherein the EKG
`is modulated by a carrier frequency and added to an audio
`signal resulting in a composite signal that is transmitted to
`the sound port of a computing device.
`14. The EKG Stethoscope of claim 12 visualizing both
`phonocardiogram and EKG concurrently on the screen of
`the computing device in the stack mode or superimposed.
`15. The EKG electrodes of claim 12 located on the chest
`piece to simplify application of said EKG Stethoscope on
`patients.
`16. The EKG electrodes of claim 12 attached to the
`
`subject’s skin connected to the said EKG Stethoscope via
`standard wired EKGleads.
`
`17. The EKG Stethoscope of claim 12 having meansfor
`visualizing the EKG and audio waveform on a read-out
`display located on the chest piece.
`18. The EKG Stethoscope of claim 12 having means to
`signal the operator events of the EKG cycle, whereby said
`event will include the QRS complex, which corresponds to
`
`the start of systole, the P-wave, which corresponds to the
`start of atrial depolarization, and T-wave, which corresponds
`to the start of diastole.
`19. The EKG Stethoscope of claim 12 having meansfor
`transmitting sounds from the chest piece to the operators
`ears.
`
`20. The EKG Stethoscope of claim 12 having the chest
`piece mounted on a computing device, such as a PDA.
`21. The EKG Stethoscope of claim 12 incorporating
`means for automatic identification of respiratory cycle,
`automatic identification of events on EKG, and automatic
`identification of heart sounds components.
`22. The physiological data acquisition system using said
`amplitude modulation method of claim 1 to transmit sound
`recordings from 2 or more sound pick-up sensors into said
`sound input port of the computing device whereby each
`channel is modulated by its own carrier frequency.
`*
`*
`*
`*
`*
`
`13
`
`13
`
`