Service manual

112 Technical Overview Welch Allyn Propaq Encore Vital Signs Monitor
can then be digitized. The data from the ADC is processed by the CPU and then sent to
the SCP board for transmission to the Propaq Encore monitor's CPU.
SpO
2
signal level is controlled through the variable gain stage of the inverting amplifier
and the output current of the LED current driver. By controlling both signal gain and
current drive, the CPU can maintain the best possible signal level for processing.
Amplifiers sense the SpO
2
signal levels at two points, directly sending their outputs to the
CPU. The CPU monitors these levels as it sets the gain stages of the inverting amplifier
and LED current driver.