GE TruSat Product manual

GE Healthcare
TruSat™ Pulse Oximeter
Technical Reference Manual

GE Healthcare
TruSat™ Pulse Oximeter
Technical Reference Manual
6050-0006-81
March 2005

Important
Rx Only (USA)
Attention! Consult the accompanying instructions, including all safety
precautions, before using or servicing this device.
Responsibility of the manufacturer
The safety, reliability, and performance of this device can be assured by the
manufacturer only under the following conditions:
• Assembly, extensions, readjustments, modifications, and repairs are carried out by
authorized personnel.
• The electrical installation complies with relevant standards and regulations.
• The device is used in accordance with the TruSat User’s Guide and is serviced and
maintained in accordance with this manual.
Service and repair
Service and repair procedures must be performed by authorized service personnel.
Repair this device or its parts only in accordance with instructions provided by the
manufacturer. To order replacement parts or for assistance, contact an authorized
service office. When shipping the monitor for repair, clean the monitor, allow it to dry
completely, and pack it for shipment in the original shipping container, if possible.
Trademarks
Datex®, Ohmeda®, TruSat™ and other trademarks (ComWheel™, OxyTip®, PIr®,
TruSignal™, TruTrak®) are the property of GE Healthcare Finland Oy. All other product
and company names are the property of their respective owners.
0537
GE Healthcare Finland Oy
Helsinki, Finland
+ 58 10 94 11
www.gehealthcare.com
© 2005 General Electric Company. All rights reserved.

ontents
i
1. Product Description and Specifications .........................................1–1
1.1 General description.......................................................................................................... 1–1
Related information..........................................................................................................................1–1
Technical competence....................................................................................................................1–1
1.2 Monitor features ................................................................................................................ 1–2
Screen display, controls, and indicators ................................................................................1–2
Connectors............................................................................................................................................1–
Information label and symbols...................................................................................................1–
1.3 Safety precautions............................................................................................................ 1–4
Warnings................................................................................................................................................1–4
Cautions..................................................................................................................................................1–4
Disposal ..................................................................................................................................................1–4
1.4 Specifications....................................................................................................................... 1–5
Factory settings..................................................................................................................................1–5
Measurement.......................................................................................................................................1–5
Monitor....................................................................................................................................................1–6
1.5 ompliance ........................................................................................................................... 1–8
Related standards and tests ........................................................................................................1–8
Electromagnetic compatibility (EMC).......................................................................................1–9
2. Theory of Operations ..............................................................................2–1
2.1 Functional block diagram.............................................................................................. 2–1
2.2 Measurement principles ................................................................................................ 2–2
TruSignal Enhanced SpO2.............................................................................................................2–2
PIr pulsatile value...............................................................................................................................2–2
Signal processing...............................................................................................................................2–2
2.3 Power supply and battery ............................................................................................ 2–2
2.4 System board....................................................................................................................... 2–3
Microcontroller....................................................................................................................................2–4
2.5 Display board....................................................................................................................... 2–4
2.6 Trend Download board (RS-232)................................................................................ 2–5
Alarm event relay ..............................................................................................................................2–6
3. Troubleshooting.........................................................................................3–1
3.1 Troubleshooting guide.................................................................................................... 3–1
Error numbers...................................................................................................................................... –
3.2 System board components .......................................................................................... 3–4
System board test points............................................................................................................... –5
System board connectors............................................................................................................. –5
ID connector (X1)....................................................................................................................... –5
ComWheel connector (X2).................................................................................................... –5
Speaker connector (X4).......................................................................................................... –5
Pulse oximetry connector (X5) ........................................................................................... –6
Battery connector (X6)........................................................................................................... –6
DC line power connector (X7) ............................................................................................. –6
Trend Download board connector (X8).......................................................................... –7

ontents
ii
Software upgrade connector (X11)................................................................................. –7
Display board connector (X12).......................................................................................... –8
3.3 Display board components...........................................................................................3–9
Display board test points .............................................................................................................. –9
Display board connector............................................................................................................. –10
System board connector (X1)........................................................................................... –10
3.4 Trend Download board (RS-232) components ................................................. 3–11
Trend Download board connectors....................................................................................... –11
System board connector (X1)........................................................................................... –11
RS-2 2 connector (X2) ......................................................................................................... –12
ID connector (X ) .................................................................................................................... –12
4. Service Procedures...................................................................................4–1
4.1 Functional check ..................................................................................................................4–1
Changing the line power filter..................................................................................................... 4–2
Setting the clock................................................................................................................................. 4–
Electrical safety check.................................................................................................................... 4–
Ground resistance test.......................................................................................................... 4–
4.2 Planned Maintenance........................................................................................................4–4
Battery.................................................................................................................................................... 4–4
Cleaning ................................................................................................................................................. 4–4
4.3 Software upgrade................................................................................................................4–5
Checking the current software versions................................................................................ 4–5
Installing the software upgrade................................................................................................. 4–5
4.4 Trend Download upgrade................................................................................................4–6
Installing the Trend Download board...................................................................................... 4–7
4.5 Alarm annunciation............................................................................................................4–8
Customizing a cable......................................................................................................................... 4–8
Enabling alarm annunciation...................................................................................................... 4–9
Before installing the Trend Download board............................................................. 4–9
After installing the Trend Download board...............................................................4–10
Relay switch fuse replacement................................................................................................4–11
4.6 Repair procedures............................................................................................................ 4–12
Monitor disassembly .....................................................................................................................4–12
Right (ComWheel) side disassembly.............................................................................4–12
Left side disassembly...........................................................................................................4–12
Housing disassembly...........................................................................................................4–1
Monitor assembly............................................................................................................................4–1
Housing assembly.................................................................................................................4–1
Left side assembly.................................................................................................................4–14
Right side assembly..............................................................................................................4–14
5. Service Parts................................................................................................5–1
5.1 Miscellaneous parts............................................................................................................5–1
5.2 TruSat assembly...................................................................................................................5–2
TruSat parts and service kits ....................................................................................................... 5–2
TruSat assembly drawing ............................................................................................................. 5–

1–1
1. PRODU T DES RIPTION AND SPE IFI ATIONS
This manual provides instructions for servicing the TruSat™ pulse oximeter.
This chapter contains:
• A general description of the monitor.
• Illustrations of the monitor.
• Safety precautions.
• Specifications.
• Details regarding compliance with standards for Medical Electrical Equipment.
1.1 General description
The TruSat pulse oximeter is a durable and portable monitor that measures oxygen
saturation, pulse rate, and PIr®, a relative perfusion index. The monitor is powered
by an internal battery, which is charged through an external power supply.
Important: When using the monitor for the first time or after removing it from
extended storage, charge the battery for three hours BEFORE you power ON.
The monitor contains an easy-to-read liquid crystal display (LCD) with a backlight
for low-light conditions. The monitor also contains on-screen controls for changing
monitor settings, a lock function, and an alarm system that generates audible and
visual alarm signals.
The optional Trend Download board allows users to set the monitor clock, print, and
download trends to a computer. Monitors can be factory-configured with this option.
An upgrade kit is also available.
Important: Only OxyTip®+ sensors can be used with this monitor.
Related information
For a detailed description of the functions and general operating guidelines of the
monitor, refer to the TruSat User’s Guide.
For information related to sensors (sensor application and cleaning, for example),
refer to the instructions for the sensor.
Technical competence
AUTION: Only qualified service personnel should perform the procedures
described in this manual.
Only authorized service personnel or competent individuals who are experienced
with servicing medical devices of this nature should perform the procedures
described in this manual.

TruSat Technical Reference Manual
1–2
1.2 Monitor features
Screen display, controls, and indicators
NOTE: The monitor is shown without the handle.
Figure 1-1. Monitor features
1 Oxygen saturation (SpO2) measurement value
2 SpO2 high and low alarm limit settings, adjustable
Pulse rate measurement value
4 Pulse rate high and low alarm limit settings, adjustable
5 Plethysmographic pulse bar (pleth bar)
6 Alarm LED
7 Alarm Silence button
8 ComWheel navigation and selection knob for changing monitor settings
9 Display area for on-screen control symbols (set pulse beep volume, set alarm
volume, switch backlight ON/OFF, display PIr, print) and the lock symbol
10 Battery indicator
11 Power button and external power LED
Refer to the TruSat User’s Guide for detailed descriptions of all controls and
indicators.

Product Description and Specifications
1–
onnectors
WARNING: When you connect equipment to the monitor, you are
configuring a medical system and are responsible for ensuring that the
system complies with IE 60601–1–1 and with local requirements. onnect
only external devices specified for use with the monitor.
WARNING: Use only sensors and cables authorized for use with this monitor.
Failure to do so may cause interference with the measurement or result in
increased emissions, decreased immunity, or damage to the equipment or
system.
Figure 1-2. Monitor connectors
Information label and symbols
A label on the underside of the monitor contains the model number, serial number,
date of manufacture, and other information about the monitor. The following
symbols also appear on this label and/or on the packaging for the monitor:
Sensor connector; defibrillation-
proof type BF applied part
DC current
RS-2 2 connector for the Trend
Download option
Manufacturer
Power supply connector;
external power in
Other symbols on the monitor or the screen are described in the TruSat User’s Guide.
Sensor connector
Connect an OxyTip+ sensor
or cable only.
Trend Download connector (RS-232)
Connect the TruSat/PC RS-2 2 cable or the
TruSat/serial printer cable.
Power connector
Plug the power supply cable into this connector. Then, plug the
power cord into the power supply and into the AC power outlet.

TruSat Technical Reference Manual
1–4
1.3 Safety precautions
Precautions associated with following safe practices while using the monitor appear
throughout this manual. General precautions are listed below. Carefully read all
precautions in this manual before repairing or using the monitor.
NOTE: For complete information about the safe and appropriate use of a sensor,
consult the instructions for that sensor.
Warnings
WARNINGS indicate potentially harmful situations that may cause injury to
a patient or operator.
• Do not use the monitor if the startup tones do not sound, the validity of data is
questionable, or if the monitor fails to function as described. Refer to the
appropriate sections of this manual to identify and correct the malfunction.
• Do not use the monitor in the presence of any flammable anesthetic mixture.
• Use only hospital-grade, grounded power outlets.
• Use only sensors and cables specified for use with this monitor. Failure to do so
may cause interference with the measurement or result in increased emissions,
decreased immunity, or damage to the equipment or system.
• This monitor is not intended for use in a magnetic resonance imaging (MRI)
environment.
• When you connect equipment to the monitor, you are configuring a medical
system and are responsible for ensuring that the system complies with
IEC 60601–1–1 and with local requirements. Connect only external devices
specified for use with this monitor.
• Power OFF and disconnect the monitor from external power before performing
any procedure that involves disassembly of the monitor.
autions
AUTIONS indicate conditions that may lead to equipment damage or
malfunction.
• Internal electronic components are susceptible to damage by electrostatic
discharge. To avoid damage when disassembling the monitor, observe the
standard precautions and procedures for handling static-sensitive components.
• Do not store or use the monitor outside the temperature and humidity ranges
stated in the Specifications section of this manual.
• Never use a battery if its insulative wrap is ripped, torn, or has other visible
damage. A damaged battery wrap can cause internal shorting, overheating, or
other equipment damage.
Disposal
Recycle or dispose of this medical device, its components, and its packing materials
in accordance with local environmental and waste disposal regulations.

Product Description and Specifications
1–5
1.4 Specifications
Specifications are nominal and are subject to change without notice.
Factory settings
Setting Range Factory setting
High SpO2 alarm limit 51 to 100% or OFF (— —) OFF
Low SpO2 alarm limit 50 to 99% or OFF (— —) 85
High pulse rate alarm limit 0 to 2 5 bpm or OFF (— — —) 1 0
Low pulse rate alarm limit 0 to 2 5 bpm or OFF (— — —) 40
Backlight ON or OFF ON
Pulse beep volume 0 (OFF), 1, 2, , or 4 * 2
Alarm volume 1 (low), 2, , or 4 * 2
Line power filter 50 Hz or 60 Hz 60 Hz
* For more information, see Audio later in this section.
Measurement
General
Pulse oximetry sensors: OxyTip+ sensors only
Method: red and infrared light absorption
Red LED wavelength range: 650 to 670 nm
Infrared (IR) LED wavelength range: 9 0 to 950 nm
Average power: ≤ 1 mW
SpO 2
Calibrated for functional oxygen saturation
Calibration range: 70 to 100%
Measurement and display range: 1 to 100%
Display resolution: 1%
First reading, full accuracy: ≤ 10 seconds
Accuracy, Arms
(root mean square of paired values; previously represented by ± 1 SD):
70 to 100% ± 2 digits (without motion)
70 to 100% ± digits (during clinical motion)1
70 to 100% ± 2 digits (during clinical low perfusion)
Below 70% unspecified
SpO2 measurement accuracy is based on deep hypoxia studies using OxyTip+
sensors on volunteer subjects. Arterial blood samples were analyzed simultaneously
on multiple CO-oximeters.
NOTE: Accuracy may vary for some sensors; always check the instructions for the
sensor.
1
Applicability: OxyTip+ Adult/Pediatric and AllFit sensors.

TruSat Technical Reference Manual
1–6
Pulse rate
Measurement and display range: 0 to 250 beats per minute (bpm)
Display resolution: 1 bpm
First reading, full accuracy: ≤ 15 seconds
Accuracy
0 to 250 bpm: ± 2 digits or ± 2%, whichever is greater (without motion)
0 to 250 bpm: ± 5 digits (during motion)
0 to 250 bpm: ± digits (during low perfusion)
PIr pulsatile value
Measurement and display range: 0.01 to 9.99
Display resolution: 0.01 PIr
Monitor
General
Lock function: locks/unlocks alarm limits and other settings
Factory calibrated; power-on self-test with calibration check
Recovery time after exposure to defibrillation voltage: ≤ 0 seconds
Display
Liquid crystal display (LCD)
Backlight LED: ON or OFF
Plethysmographic pulse bar (pleth bar): ten-segment column; pulsates to indicate
pulse rate and signal strength
Display update time
SpO2, pulse rate, and PIr values: 1 second ± 0.25 second
Plethysmographic pulse bar: 20 Hz minimum (.05 second)
Alarms
Visual and audible indicators for physiological alarms (SpO2 and pulse rate limit
alarms) and technical alarms (sensor condition, battery condition, internal
malfunction)
Visual alarm indicator, red/yellow LED
High priority alarm: red ON or red flashing ON/OFF
Medium priority alarm: yellow flashing ON/OFF
Visibility (operator positioned in front of monitor: 4 m (1 ft.) at 0° angle in any
direction
NOTE: When an SpO2 or pulse rate alarm limit is violated, the related
measurement flashes ON/OFF.
Audible alarm indicator: pattern varies according to alarm type and priority
Alarm Silence button: silences alarms for 2 minutes (press once; screen symbol is
displayed) or indefinitely (press times; screen symbol flashes ON/OFF)
NOTE: If an alarm condition is not present, the alarm LED is lit yellow to indicate
future alarms will be silenced.

Product Description and Specifications
1–7
Audio
Pulse rate beep: tone rises as oxygen saturation increases and falls as it decreases
Adjustable alarm volume and pulse beep volume: 4-segment on-screen controls
Volume intensity at distance of 1 m ( .28 ft.): 45 dB minimum to 85 dB maximum
External power
Power supply (AC to DC converter)
AC power input: 100–240 V, 0.5 A, 50–60 Hz
Power supply (DC to DC)
DC power input from vehicle cigarette lighter: 12 V
Power supply output to monitor: 12 VDC, 1.25 A, 15 watt
Power indicator (green LED): ON while monitor is connected to external power
Line power filter (monitor setting): 50 Hz or 60 Hz
Internal battery power
Type: Internal, rechargeable, nickel metal hydride (NiMH), AH, 12 VDC, 150 mA
Self-discharge when stored at room temperature (typical for all NiMH batteries):
at least 0% of a full charge remains after months of storage
Capacity, fully charged, operating at room temperature:
Without Trend Download option: 5 hours
With Trend Download option: 24 hours
NOTE: Continuous use of the backlight reduces the time approximately 50%.
Charging time (full capacity): .5 hours typical
Battery indicator: 4-segment symbol; shaded segments represent battery charge
(0 shaded = low or depleted; 4 shaded = fully charged)
Automatic power OFF to conserve battery: 20 minutes after monitoring stops
Trend Download option
Trend data storage: 48 hours with a data storage resolution of 1 data point every
4 seconds
RS-2 2 serial port: DIN 6 circular connector
19.2K baud, 8 data bits, 1 start bit, 1 stop bit
Handshaking (RTS, CTS), full duplex, no parity
Environmental conditions
NOTE: To maximize battery life, store the monitor at room temperature.
Operating Transport and Storage
Temperature 10 to 40 ºC
(50 to 104 ºF)
–40 to 70 ºC
(–40 to 158 ºF)
Relative humidity,
noncondensing
20 to 95% 5 to 95%
Atmospheric pressure 1060 to 697 hPa 1060 to 188 hPa
Approximate elevation – 78 to 048 m
(–1240 to 10,000 ft.)
– 78 m to 12.2 km
(–1240 to 40,000 ft.)
Dimensions and weight
Width/Depth/Height including handle = 21.8 x 11.5 x 10. cm (8.5 x 4.5 x 4 inches)
Weight = 1.25 kg (2.76 pounds)
1.47 kg ( .26 pounds) with Trend Download option

TruSat Technical Reference Manual
1–8
1.5 ompliance
European Union Medical Device Directive 93/42/EE : Class IIb
EN 60601-1 Medical electrical equipment – Part 1 General requirements for safety
(including Amendments 1 and 2)
• Type of protection against electric shock: Class I equipment/Internal electrical
power source
• Degree of protection against electric shock: Defibrillation-proof type BF applied
part
• Degree of protection against ingress of water (EN 60529): IPX2
• Not suitable for use in the presence of flammable anesthetic mixtures
• Mode of operation: Continuous
EN 60601-1-2 (2nd Edition) Electromagnetic compatibility – Requirements and tests For
details, see Electromagnetic compatibility (EMC) later in this section.
ISPR 11/EN 55011 (Protection against emissions): Group I, Class B
IE 60601-1-8 Alarm systems – General requirements, tests and guidance for alarm
systems in medical electrical equipment and systems
Medical electrical equipment classified in the US and Canada with respect
to electric shock, fire, and mechanical hazards only, in accordance with
the Canadian Standards Association CAN/CSA C22.2 No. 601.1 and
Underwriters Laboratories Inc. UL 2601–1.
Related standards and tests
Standard Description
EN 60601-1, clause 21 Rigidity, strength, handle loading drop test
EN 60601-1, clause 42 Temperature
EN 60601-1, clause 48 Non-toxic materials used for surface of case
EN 60601-1, sub-clause 59.2(b) Resistance of case to heat and fire
EN 865, clause 44 Overflow, spillage, ingress of liquids, cleaning
and disinfection
IEC 61000- -2 Harmonic emissions
IEC 61000- - Voltage fluctuations and flicker emissions
IEC 61000-4-2, level Electrostatic discharge immunity
IEC 61000-4- , level 2 Radiated RF electromagnetic field immunity
IEC 61000-4-4, level Electrical fast transient and burst immunity
IEC 61000-4-5, level Surge immunity
IEC 61000-4-6 Susceptibility to conducted EMI
IEC 61000-4-8 Power frequency magnetic fields
IEC 61000-4-11, Table 7 Operation during line voltage variations
IEC 60068-2- 2 Operation during physical shock/drop and
repetitive drop
UL 2601-1, clause 55 Impact test

Product Description and Specifications
1–9
Electromagnetic compatibility (EM )
When using this monitor, take precautions to ensure electromagnetic compatibility.
Indications that the monitor is experiencing electromagnetic interference include,
for example, a dashed display or sudden changes in the pleth bar height that do not
correlate to the physiological condition of the patient. This interference may be
intermittent and careful correlation between the effect and its possible source is
important. Indications of interference should not occur if the monitor is used within
its intended electromagnetic environment.
Electromagnetic interference, including interference from portable and mobile radio
frequency (RF) communications equipment, can affect this monitor. When using the
monitor, take precautions to ensure electromagnetic compatibility.
Recommended Separation Distances between
Portable and Mobile RF ommunications Equipment and the TruSat
The TruSat pulse oximeter is intended for use in an electromagnetic environment in which RF disturbances are
controlled. The customer or the user of the monitor can prevent electromagnetic interference by maintaining a
minimum distance between portable and mobile RF communications equipment (transmitters) and the monitor as
recommended below, according to the maximum output power of the communications equipment.
Separation distance according to the frequency of the transmitter
m
Rated maximum output
power of the transmitter
W150 kHz to 80 MHz 80 MHz to 800 MHz 800 MHz to 2,5 GHz
0.01 0.07 0.07 0.07
0.1 0.22 0.22 0.22
1 0.70 0.70 0.70
10 2.2 2.2 2.2
100 7.0 7.0 7.0
For transmitters rated at a maximum output power not listed above, the recommended separation distance d in
meters (m) can be estimated using the equation applicable to the frequency of the transmitter, where P is the
maximum output power rating of the transmitter in watts (W) according to the transmitter manufacturer.
NOTE 1: At 80 MHz and 800 MHz, the separation distance for the higher frequency range applies.
NOTE 2: These guidelines may not apply in all situations. Electromagnetic propagation is affected by absorption
and reflection from structures, objects, and people.
Guidance and manufacturer’s declaration - electromagnetic emissions
The TruSat pulse oximeter is suitable for use in the electromagnetic environment specified below. The customer or the
user of the monitor should assure that it is used in such an environment.
Emissions test ompliance Electromagnetic environment - guidance
RF emissions
CISPR 11 Group 1
The TruSat uses RF energy only for its internal function.
Therefore, its RF emissions are very low and are not likely to
cause any interference in nearby electronic equipment.
RF emissions
CISPR 11 Class B
Harmonic emissions
IEC 61000- -2 Class A
Voltage fluctuations/flicker emissions
IEC 61000- - Complies
The TruSat is suitable for use in all establishments, including
domestic establishments and those directly connected to
the public low-voltage power supply network that supplies
buildings used for domestic purposes.

TruSat Technical Reference Manual
1–10
Guidance and manufacturer’s declaration - electromagnetic immunity
The TruSat pulse oximeter is intended for use in the electromagnetic environment specified below. The customer or
the user of the monitor should assure that it is used in such an environment.
Immunity test EN 60601-1-2 test level ompliance level Electromagnetic environment -
guidance
Electrostatic
discharge (ESD)
IEC 61000-4-2
± 6 kV contact
± 8 kV air
± 6 kV contact
± 8 kV air
Floors should be wood,
concrete, or ceramic tile. If
floors are covered with
synthetic material, the relative
humidity should be at least
0%.
Electrical fast
transient/burst
IEC 61000-4-4
± 2 kV for power supply lines
± 1 kV for input/output lines
± 2 kV for power supply lines
± 1 kV for input/output lines
Mains power quality should be
that of a typical commercial
or hospital environment
Surge
IEC 61000-4-5
± 1 kV differential mode
± 2 kV common mode
± 1 kV differential mode
± 2 kV common mode
Mains power quality should be
that of a typical commercial
or hospital environment.
Voltage dips,
short
interruptions
and voltage
variations on
power supply
input lines
IEC 61000-4-11
< 5 % UT
(> 95 % dip in U T) for 0,5 cycle
40 % UT
(60 % dip in UT) for 5 cycles
70 % UT
( 0 % dip in UT) for 25 cycles
< 5 % UT
(> 95 % dip in U T) for 5 sec.
< 5 % UT
(> 95 % dip in U T) for 0,5 cycle
40 % UT
(60 % dip in UT) for 5 cycles
70 % UT
( 0 % dip in UT) for 25 cycles
< 5 % UT
(> 95 % dip in U T) for 5 sec.
Mains power quality should be
that of a typical commercial
or hospital environment. If the
user requires continued
operation during power mains
interruptions, it is
recommended that the TruSat
be powered from an
uninterruptible power supply
or a battery.
Power frequency
(50/60 Hz)
magnetic field
IEC 61000-4-8
10 A/m A/m Power frequency magnetic
fields should be at levels
characteristic of a typical
location in a typical
commercial or hospital
environment.
NOTE: UT is the AC mains voltage prior to application of the test level.

Product Description and Specifications
1–11
Guidance and manufacturer’s declaration - electromagnetic immunity
The TruSat pulse oximeter is intended for use in the electromagnetic environment specified below. The customer or
the user of the monitor should assure that it is used in such an environment.
Electromagnetic environment - guidance
Portable and mobile RF communications equipment should be used no closer to any part of the monitor, including
cables, than the recommended separation distance calculated from the equation applicable for the frequency of the
transmitter.
NOTE: These guidelines may not apply in all situations. Electromagnetic propagation is affected by absorption and
reflection from structures, objects, and people.
Immunity test EN 60601 test level ompliance
level Recommended Separation Distance
Conducted RF
IEC 61000-4-6
Vrms
150 kHz to 80 MHz
5 V
Radiated RF
IEC 61000-4-
V/m
80 MHz to 2.5 GHz
5 V/m
10 V/m
80 MHz to 800 MHz
800 MHz to 2.5 GHz
where P is the maximum output power rat ing of the
transmitter in watts (W) according to the transmitter
manufacturer and d is the recommended separation
dis tance in meters (m).
NOTE: At 80 MHz and 800 MHz, the separation distance
for the higher frequency range applies.
Interference may occur in the vicinity of equipment marked with this symbol.
Field strengths from fixed RF transmitters, as determined by an electromagnetic site survey,a should be less than the
compliance level in each frequency range.b
aField strengths from fixed transmitters, such as base stations for radio (cellular/cordless) telephones and land
mobile radios, amateur radio, AM and FM radio broadcast, and TV broadcast cannot be predicted theoretically
with accuracy. To assess the electromagnetic environment due to fixed RF transmitters, an electromagnetic site
survey should be considered. If the measured field strength in the location in which the TruSat is used exceeds the
applicable RF compliance level above, the TruSat should be observed to verify normal operation. If abnormal
performance is observed, additional measures may be necessary, such as re-orienting or relocating the TruSat.
bOver the frequency range 150 kHz to 80 MHz, field strengths should be less than 5 V/m.

TruSat Technical Reference Manual
1–12

2–1
2. THEORY OF OPERATIONS
This chapter contains:
• Functional block diagram.
• SpO2, pulse rate, and PIr measurement principles.
• Functional descriptions of the power supply, System board, Display board, and
the Trend Download board (RS-2 2).
2.1 Functional block diagram
A/D
converter
Data & Clocks
Sensor
Digital
isolators
Isolated
power supply
Data & status info
DSP
VDD
LED ti ing
Code & data
e ory
Voltage
regulators
Battery charger
Clock
Display board connector
Co Wheel
Backlight
4.2 V regulator
LCD
AC & alar LEDs
V-CORE
regulator
Backlight
supply
Watchdog
icro
Keys
Display control
Microprocessor
Speaker
driver
LED drive
Analog
front end
AUX A/D
converter
CPLD
Line power supply
ON/OFF &
alar switches
Display
drivers
Trend Download
board
Alar
Figure 2-1. Functional block diagram

TruSat Technical Reference Manual
2–2
2.2 Measurement principles
TruSignal™ Enhanced SpO2
TruSignal Enhanced SpO2 offers improved performance, especially during
challenging conditions of clinical motion and low perfusion. With ultra-low-noise
technology, TruSignal selects the appropriate clinically-developed algorithm to
compensate for weak or motion-induced signals and generate reliable saturation
readings.
PIr pulsatile value
The perfusion index measurement—the PIr pulsatile value—is a quick and easy-to-
use clinical tool that provides a dynamic numeric reflection of perfusion at the
sensor site. PIr is a relative value that varies from patient to patient.
The PIr pulsatile value indicates the strength of the pulse signal at the sensor
site—the higher the PIr value, the stronger the pulse signal. A strong pulse signal
increases the validity of SpO2 and pulse rate data. Clinicians can use the PIr value to
compare the strength of the pulse signal at different sites on a patient in order to
locate the best site for the sensor—the site with the strongest pulse signal.
Signal processing
This pulse oximeter uses a two-wavelength pulsatile system—red and infrared
light—to distinguish between oxyhemoglobin (O2Hb) and reduced hemoglobin (HHb).
The light is emitted from the oximeter sensor, which contains a light source and a
photodetector.
• The light source consists of red and infrared light-emitting diodes (LEDs).
• The photodetector is an electronic device that produces an electrical current
proportional to incident light intensity.
The two light wavelengths generated by the LEDs are transmitted through the tissue
at the sensor site and are modulated by arterial blood pulsation. The photodetector
in the sensor converts the light intensity information into an electronic signal that is
processed by the monitor.
The TruSat pulse oximeter uses the functional calibration method.
2.3 Power supply and battery
A Globetek power supply converts power from an AC power source (100 to 240 V, 0.5 A,
50-60 Hz) and outputs power to the monitor (+12 VDC, 1.25 A, 15 watts). It also
provides the necessary isolation between the patient and the AC power supply.
An optional 12 VDC to 12 VDC power supply is available. It can be connected to an
auxiliary power source, such as a vehicle cigarette lighter.
When the monitor is not connected to an external power supply, it is powered by an
internal rechargeable NiMH battery ( AH, 12 VDC, 150 mA). The battery connects to
the System board.