SonoSite MicroMaxx, Руководство по обслуживанию

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16 Chapter 3: System Overview
ECG Module
The ECG module allows a representation of the heart electrical activity to be displayed in real time with ultrasound
images acquired and displayed on the System video display.
The ECG module interfaces to the patient through three (3) ECG leads: Right Arm ECG lead (RA), Left Arm ECG lead
(LA), and Left Leg ECG lead (LL). The ECG received signal from the ECG electrodes are isolated, amplified, and
filtered by the ECG module before it is sent to the System for further processing and display.
The ECG module and cable are an integrated assembly. The module receives power from the System. Patient
isolation is provided by the ECG module, allowing the connection and signals to the System to be System-ground
referenced. The isolation between the patient and the System meets the requirements of IEC 601-1 for Type BF
equipment.
The top-level functional block diagram is shown in Figure 3.3 .
Figure 3.3 ECG Module Block Diagram
The ECG module can be partitioned into six (6) different blocks:
• Pre-amplifier block
• Isolation block
• High pass filter block
• Variable amplifier block
• Low pass filter block
• Power supplies block
Pre-Amplifier The pre-amplifier block provides the interface to the ECG leads. It provides high levels of
common mode rejection and the initial gain for the ECG signal. This block also provides a
high pass function to eliminate any large direct current (DC) offsets to allow a
moderately high gain to be set before isolation, allowing the front end to set the input
equivalent noise of the electrical ECG signal path.
Isolation The isolation block provides voltage isolation for the analog signal. The voltage isolation
between the patient and the system meets the requirement of the ANSI/AAMI EC13
specification.
High Pass Filter The high pass filter block removes the low frequency components and biases the opt
coupler output for the received ECG signal.
Variable
Amplifier The variable amplifier blocks provide additional gain for the received ECG signal. The
blocks are used to boost the signal. There are three gain settings for the variable
amplifier, controlled by the system through the control bus.
ECG Module
Analog out
Sense
To system
ECG leads
To patient
3
VPWR I2C BUS FLTR_CLK PWR_CLK
From system
2