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For Measurement of ECG. m5151117 Yumiko Kimezawa. Outline. Our Architecture Important Things in Measurement of ECG Signal Book Knowledge Question Requirements for Measurement of ECG Future Work. Our Architecture. Processing results are sent through the Ethernet. Sensor. A/D
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RPS For Measurement of ECG m5151117 Yumiko Kimezawa
Outline RPS • Our Architecture • Important Things in Measurement of ECG Signal • Book Knowledge • Question • Requirements for Measurement of ECG • Future Work
Our Architecture RPS Processing results are sent through the Ethernet Sensor A/D converter Processing Filter RAM Results From patient
Important Things in Measurement of ECG Signal RPS • Clinically-important frequency component of ECG signal • - 0 ~ 250Hz Change in voltage inside this range must be faithfully reproduced • Change in voltage in chest wall • Less than 3mV (very weak) • Measurement in environments with much noise Voltage gain of high signal-to-noise ratio (250 to 1000 times) must be gained • Signal-to-noise ratio: The ratio of signal power to the noise power
Book Knowledge RPS • An example of block diagram illustrating cardiography equipment Lead Code Head amplifier Isolation circuit Impedance converter Lead network Power Circuit Main amplifier Micro computer ADC Output equipment
Book Knowledge RPS • An example of block diagram illustrating cardiography equipment Lead Code Head amplifier Isolation circuit Impedance converter Lead network Power Circuit • This circuit prevents body’s impedance from being lower than input circuit’s impedance Main amplifier Micro computer ADC Output equipment
Book Knowledge RPS • An example of block diagram illustrating cardiography equipment Lead Code Head amplifier Isolation circuit Impedance converter Lead network Power Circuit • Constitution of 12-lead from the combination of sensors • A~J : Sensors • Example • Ⅰ: Output between A and E • aVR: Output between A and F Main amplifier Micro computer ADC Output equipment
Book Knowledge RPS • ECG signal is very weak • The signal must not be amplified suddenly • Differential amplifier is usedas head amplifier • An example of block diagram illustrating cardiography equipment An amplifier is needed Lead Code Head amplifier Isolation circuit Impedance converter Lead network The signal is amplified in stages Power Circuit • Noises are reduced • signal-to-noise ratio is improved Main amplifier Micro computer ADC Output equipment
Book Knowledge RPS • An example of block diagram illustrating cardiography equipment Lead Code Head amplifier Isolation circuit Impedance converter Lead network Power Circuit • For securing of security, impedance converter, lead network and head amplifier have to be isolated from main amplifier, power circuit and A/D converter Main amplifier Micro computer ADC Output equipment
Question RPS • A/D converter (AD9254) is included in HSMC • Pipelined switched capacitor ADC • Sampling frequency: 150MHz • Resolution: 14-bit • Power: 430mW HSMC Performance is overmuch • Clinically-important frequency component of ECG signal is from 0 to 250Hz 500Hz is enough for sampling frequency • Using a lot of electricity • Conversion process is complex • Using A/D converter in HSMC is of questionable value
Requirements for Measurement of ECG RPS • An amplifier is needed • Securing of security also have to be considered
Future Work RPS • Studying cardiography equipment using digital filtering techniques
心電計の回路を表すブロック図の例 RPS 誘導コード インピーダンス変換器 前置 増幅器 アイソレーション回路 誘導ネットワーク 電源回路 主増幅器 マイクロコンピュータ AD変換器 出力装置
標準12誘導を作るための誘導ネットワークの原理標準12誘導を作るための誘導ネットワークの原理 RPS B C D A~Jの各点の出力を組み合わせる。 例えば、第Ⅰ誘導はAとE、aVRはAとFを組み合わせたものとなる。 A E J F I H G