ECG Tester

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AMMAN ALAHLIA UNIVERSITY
Al-Ahliyya Amman UniversityFaculty of
EngineeringBiomedical Engineering Department
AMMAN ALAHLIA UNIVERSITY
DESIGN IMPLEMENTATIN OF A Wireless
Electrocardiogram monitor By
Eng.Alaa Abu Ayyash Eng
.Yazan Al-Qawasmi Supervised by Dr. Jamal
Nazzal June, 2006
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WIRELESS ECG
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Electrocardiographs

• Heart activity causes electrical changes
  throughout the body, with every heartbeat.
• ECG can detect these voltage changes on the skin.
• Output is printed in paper
• or on a computer screen.

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INTRODUCTION

• The electrocardiogram (ECG or EKG) is a
• noninvasive test that is used to reflect
• underlying heart conditions by measuring
• the electrical activity of the heart. By
• positioning leads (electrical sensing devices)
  on the body in standardized locations,

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INTRODUCTION

• ECG can be used to
• the rate and regularity of heartbeats
• The position of the chambers
• the presence of any damage to the heart
• effects of drugs and devices used to regulate the
  heart
• provide diagnosis when someone has chest pains or
  palpitations.

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ECG WAVEFORM

• The QRS complex is where the stronger ventricles
• fire, pushing blood through the pulmonary
• artery to the lungs, and through the aorta to the
  
• Body.

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ECG WAVEFORM

• The P wave is seen. This corresponds to
• both the atrium contracting (depolarizing) and
• priming the ventricle with blood.
• The T wave is the time at which the
• ventricles repolarize themselves for the next
• beat

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How to detect ECG Waveform

• Leads are placed on the body in several
• pre-determined locations, usually the extremities
  or the front of the chest, to provide information
  about heart conditions.

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ECG-12 LEAD
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TYPICAL ELECTROCARDIOGAM
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PROJECT

• For our final project, we implemented a
• wireless electrocardiogram monitor

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High-Level Design
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INPUT SIGNAL

• Three leads are placed on the subject
• usually one on each side of the chest and
• on the lower abdomen, This signal is sent
• to the amplifier .

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Amplifier Circuit
G150K\RG
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Cont.. Amplifier Circuit

• Signal is sent to the amplifier where it
• is amplified by a factor of one thousand.
• With the reference lead of the subject
• placed to ground.

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Cont.. Amplifier Circuit

• Also we can calculate the Gain from this
• equation G150K\RG By Using a 4.7k
• resistor, a gain of 11.7 results from this
• Stage.

INA121
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Cont.. Amplifier Circuit

• Following the instrumentation amp, the signal is
  passed through two 10 uF capacitors, placed back
  to back. The capacitors are used to prevent
  baseline drift in the ECG signal.

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VOLTAGE TO FREQUENCY CONVERTER

• The signal is then sent to the voltage to
• frequency converter (VFC), which converts
• the signal to a frequency so that it can be
• transmitted

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VOLTAGE TO FREQUENCY CIRCUIT
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Cont.. VOLTAGE TO FREQUENCY CONVERTER

• The LM231/LM331 family of voltage-to-
• frequency converters.
• The output when used as a voltage-to-
• frequency converter is a pulse train at a
• frequency precisely proportional to the
• applied input voltage.

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TRANSMITTER CIRCUIT

• The following schematic describes the
• source-splitting and transmitter section of
• our project

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TRANSMITTER CIRCUIT
FM transmitter, turning a wire 4 times around the
pen allows the signal to be transmitted at 90 MHz.
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RECEIVER CIRCUIT

• This section consists a summing amplifier
• with a gain of one cascaded with an
• inverting amplifier with a gain of
• approximately two.

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RECEIVER CIRCUIT

• The summer takes the input obtained from
• the receiver (a FM radio tuned at
• approximately 90 MHz) and adds it to a
• constant voltage obtained using a simple
• voltage divider.

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RECEIVER CIRCUIT
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FREQUENCY TO VOLTAGE CONVERTER

• The following figure shows the FVC circuit.

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FREQUENCY TO VOLTAGE CONVERTER
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FREQUENCY TO VOLTAGE CONVERTER

• Equation used to calculated the voltage
• output due to the frequency response
• obtained from the LM231 data sheet

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RESULT

• the output signal is displayed on an oscilloscope

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OUTPUT SIGNAL
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Al-Ahliyya Amman UniversityFaculty of
engineeringbiomedical engineering department
Special thanks for
Dr.Jamal Nazzal Dr.Sameh
Al-Sharo Dr. Ousama Aamar By Eng.Alaa Abu
Ayyash Eng.Yazan Al-Qawasmi June, 2006