GE Cardiocap 5 Service Manual

Measurement Parameters 
Before each stimulation, the sequence offset, noise, and threshold for response detection is 
measured. Offset is a baseline of the noise measurement. Noise is calculated by the same algorithm 
as the response signal itself. The response detection threshold is calculated based on the noise. If the 
response is not greater than the threshold, it is interpreted as no response. 
The EMG response is measured as integrated muscle activity. The EMG measurement starts 3 ms after 
the...

Cardiocap/5 Technical Reference Manual 
6.4 Components for NESTPR hemodynamic parameters 
6.4.1 Serial communication 
NESTPR 
 
Figure 6-11. Serial communication and opto isolation 
Serial communication between the NESTPR unit and the CPU is done by a RS485-type bus whose 
buffers get their supply voltage (+5 VDC) from the DC/DC board. In the isolation section, their supply 
voltage (+5 V) is obtained from the isolated power supply. The data transmission rate is 500 kbps. 
The serial communication...

Measurement Parameters 
6.4.2 NIBP board 
Address Bus
 
Figure 6-12. NIBP board functional block diagram 
Pressure transducers 
The NIBP board contains two piezo-resistive pressure transducers (B1 and B2). Transducer B1 
measures the pressure of the blood pressure cuff and the pressure fluctuations caused by arterial wall 
movement. Transducer B2 detects the cuff hose type as well as Cuff loose and Cuff occlusion 
conditions. The transducers are temperature-compensated internally. They are supplied by a...

Cardiocap/5 Technical Reference Manual 
Software control 
Software controls the valves and pump. In addition to ON/OFF signals for each component, a common 
power switch for the valves and the pump is used at pump/valve failures. 
Memory 
NIBP program memory (EPROM) size is 128k × 8. The RAM (32k × 8 bit) stores variable NIBP 
measurement values. The EEPROM (64 × 16 bit) stores the calibration values for the pressure 
transducers, the pulse valve constants gained during measurements, the PC board...

Measurement Parameters 
6.4.3 ECG board 
Patient signals are connected to overload protection circuits (resistors and gas-filled surge arresters) 
and analog switches to instrumentation amplifiers. The signals are amplified by 480 and limited by 
slew rate. Then they are A/D-converted, analyzed, and transferred to the module bus in digital form. 
 
Figure 6-13. ECG board block diagram 
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Cardiocap/5 Technical Reference Manual 
Analog ECG section 
The ECG cable is connected to connector pins E1 to E6 on the input board, which contains an overload 
protection circuit. 
Analog switches connect leads to amplifiers. The state of the switches depends on the cable type. 
Lead-off, noise, and pacemaker are detected by a slew rate detector. 
Lower frequency is determined by a high-pass (HP) filter 0.5 Hz (monitor bandwidth) or 0.05 Hz 
(diagnostic or ST bandwidth). 
ECG filtering 
The...

Measurement Parameters 
When the 5-lead cable is used, the current source is between L-F and the signal is measured from the 
N, independently on the lead selection. 
The respiration amplifier consists of the operational amplifiers and the components around them. An 
analog switch controls the gain of the first stage of the preamplifier. 
The synchronous rectifier consists of the analog switches, which detect the respiration signal from 31 
kHz amplitude modulated raw signal. 
The amplifier stage...

Cardiocap/5 Technical Reference Manual 
6.4.4 STP board 
 
To NIBP Board  
Figure 6-14. STP board block diagram 
Microprocessor unit 
The STP board uses an Intel 80C196KC-16 processor with three A/D converters, external memories, 
an 8-bit data bus, a 16 MHz oscillator, an open collector reset, and a watchdog timer. The processors 
internal UART communicates with the CPU board. High speed I/O obtains the pulse control sequence 
for pulse oximetry measurement. The oscillator provides its timing clock....

Measurement Parameters 
Isolation section 
The outputs of the two opto isolators are analog signals in the isolated section, however, the signal is 
processed on logical high-low level. Reset line is an open collector type with a pull-up resistor, 
allowing the processor to use its internal watchdog function. 
Power supply section 
Isolated supply voltages of the boards are developed from +15 Vdirty voltage from the DC/DC board. 
The power supply is a switched mode circuit, where the FET transistor...

Cardiocap/5 Technical Reference Manual 
LED driving circuit 
The differential amplifier circuit measures the voltage difference that corresponds to the LED current. 
Its output is sent back to the processor in 0 to 5 V level. There are feedback circuits from LED current 
measurement and LED intensity control. 
Background light is measured by picking up a sample from the signal. The sample is modified to 0 to 5 
V level and sent to the processor. 
Measured signal preamplification 
The preamplifier is a...