GE S5 Owners Manual

Patient Side Module, E-PSM, E-PSMP (Rev. 01) 15
Document no. M1215098-002
2.2.3 ECG board in 12-lead measurement
The 12-lead ECG measurement consists of the  functions shown in Figure 7 on page 15. All 
functions are located in the ECG board except the ECG input unit.
Figure 7 12-lead ECG measurement block diagram
ECG input unit
The ECG input unit consists of the front panel connector and the ECG input connector board 
with the high voltage protection resistors. Th e connector for the 12-lead ECG cable...

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ECG preamplifiers
The buffer amplifiers are used for each lead. The “Leads off” detection is implemented by 
measuring the output level of the input buffer amplifiers with the A/D converter of the CPU. The 
ECG signals are measured using differential amplifiers.
ECG amplifiers and baseline restoration
The function of the ECG amplifiers and baseline restoration is to amplify the signal and to 
restore the baseline of the signal in the middle of the display after the...

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The high-pass filters 0.5 Hz and 0.05 Hz are done with software. The monitor sends a command 
to the hemodynamic module determining which of  the corner frequencies 0.5 Hz or 0.05 Hz is 
to be used.
The 50 Hz and 60 Hz reject filters are both lo w-pass filters with zero at 50 Hz or 60 Hz 
correspondingly. They are software based filters used for the mains supply filtering. With these 
filters the 3 dB value for low-pass filter is...

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Temperature measurement unit
The NTC-resistor value in the probe depends on the patient’s temperature. It is measured with 
the following principle described below.
The constant current source is supplied about 38 μA current through the temperature sensor 
(YSI 400-series NTC resistor). The constant current is caused a voltage over the temperature 
sensor (NTC resistor). The voltage over the temperature sensor is amplified in a differential 
amplifier stage. The...

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Pressure amplification is realized in the instrumentation amplifier. The gain of the amplifier is 
set to keep the level of the signal transferred to the A/D converter within the measurement 
range even when there are circumstantial offsets or offsets caused by the transducer. There is 
a filter before the amplifier to attenuate high frequency disturbances.
Figure 10 Pressure measurement principle
Pulse oximetry measurement...

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Figure 11 Pulse oximetry measurement block diagram
Red and infrared channel separation
It is possible to multiplex the detector signal to four different channels depending on the 
content of the signal. The detector signal must at least multiplex into infrared and red signals. 
Other channels are e.g. for diagnostic purposes.
Serial communication
An RS485 type bus driver makes the serial communication between the module and the frame. 
The data transmission rate is...

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Figure 12 Serial communication of E-PSM(P) module
Signals and isolation barrier
The communication signals transfer over the isol ation barrier by using high isolation voltage 
(6kV) opto isolators. 
Power supply section
The power for the electronics on the floating pa rt of the STP and the ECG boards is made on 
each board with the switching power supplie s connected to a high voltage isolated 
transformer. The switching power...

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2.3 Connectors and signals
2.3.1 Module bus connector
Table 8 Module bus connector description
2.3.2 Front panel connectors
Table 9 ECG connector
5 pin connectorPin No.Signal
1
2
3
4
5 GND
Vmod 13.8 - 16 V
Data +
Data -
Shield
ECG Connector Pin No. Signal Name
1
2
3
4
5
6
7
8
9
10
11 R/RA; Right arm electrode
C2/V2; Chest electrode
C3/V3; Chest electrode
L/LA; Left arm electrode
N/RL; Neutral/Right Leg Drive electrode
C1/V1; Chest electrode
C4/V4; Chest electrode...

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Table 10 SpO2 connector
Table 11 Invasive blood pressure connectors (P1, P2)
SpO2 connector  Pin No. Signal Description
1 DET_A Photodiode anode
2 DET_C Photodiode cathode
3DATA-
4Wire 1/3LED connection
5 IR_C IR LED cathode
6OUTER SHIELD
7 DET_SHIELD
8 PRB_ID Bin/ID Resistor+
9 Wire 3/5 LED Connection
10 RED_C RED LED cathode
11 DATA+
Invasive blood pressure 
connectors (Dual BP) Pin 
No.Signal Description
1BP_+V
REFBP transducer...

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Table 12 Temp connector (T1, T2)
Temp connector Pin No Signal
1 Sensor drive current
2 Input from temperature sensor, channel 1
3Not connected
4Not connected
5 Thermistor ID (LOW= Temperature error,  HIGH=YSI 400 series)
6 Cable shield
7 Analog ground
8 Input from temperature sensor, channel 2
9Not connected
10 Not connected
11 Digital ground