Functional Components; Figure 1-1. Signal Processing Block Diagram - GE TruTrak+ 3900 User Manual

•
Ability to print or transmit the data in trend memory, along with custom
patient labels, alarm limit violations, and time stamps.
•
Viewable SpO
•
Custom patient labels that appear on printer, fax, modem, and serial
communication output.
•
Two analog output channels, SpO
recorder or polysomnography machine.
•
An automatic self-test and calibration check at start-up. After start up, the
oximeter continuously performs background self-tests.
•
Rechargeable, sealed, lead-acid battery operation, including battery status
reporting.
•
A lock button function that prevents unintended changes to settings while
monitoring a patient.

Functional components

The 3900/3900P oximeter uses the following key electrical component elements to
determine SpO
•
The sensor
•
Sensor-signal processing
•
Microprocessor calculations
The sensor consists of
•
The light source—red and infrared light-emitting diodes (LEDs)
•
The photodetector—an electronic device that produces an electrical current
proportional to incident light intensity
Sensor

Figure 1-1. Signal processing block diagram

The two light wavelengths generated by the LEDs pass through the tissue at the
sensor site. The photodetector collects this light (partially absorbed and modu-
lated) and converts it into an electronic signal that is sent to the oximeter for
further processing.
The electronic circuitry receives the photodetector's electronic signal, processes it,
and passes it on to the microprocessor for calculation of the SpO
the PI pulsatile value.
r
or PI pulsatile value trend data.
2 r
, pulse rate, and PI
2
Timing
Control
Analog
Processing Converter
and pulse rate, for connecting a chart
2
pulsatile values:
r
A/D Digital
Processing
1/Overview
Input/
Output
, pulse rate, and
2
1-3