Revision D 250 Series Maternal/Fetal Monitor 2-25
2020551-001
Equipment Overview: Theory of Operation
FECG signals as well as the MECG mode lines. The MECG analog signals are
routed separately from the front panel to the MECG daughter PWA. The MSpO
2
input signals enter the SpO
2
carrier PWA directly.
Video Decoder PWA
The decoder PWA interfaces between the DSP/display PWA and the LCD panel. The
video decoder performs the translation of 18 bit color required by the LCD panel to 1 bit
color. This gives the LCD panel two distinct colors (foreground/background) controlled
by one digital signal from the DSP PWA video generator. The translation is done by
setting the unique bit patterns on the 18 video control lines. This PWA has video
transmission line receivers to receive the high speed video from the DSP PWA.
Recorder PWA
The recorder PWA is responsible for driving the recorder motor and the recorder
printhead device along with providing the main system PWA with paper out/low/
misload status. To drive the motor it receives pulses from the main system PWA and
provides the proper drive circuitry to drive the stepper motor 4 phase windings. To
drive the printhead an adjustable power supply is provided which is set to the
printhead specifications (each printhead is unique). Data to be printed and control
information is received from the main system PWA, buffered and presented to the
printhead. Sensors from the recorder assembly to detect paper low/out/misload are
received and translated to digital status lines to be sent to the main system PWA.
Communications PWA
The Communications PWA contains three basic interfaces. It supports the analog
interface (J102) to the legacy Spectra 400 surveillance system as well as other
manufacturers centrals, a 2116 external keyboard interface for strip chart annotation,
and an analog telemetry interface to the 340 telemetry system. The communications
PWA communicates to the system by directly plugging into the main system PWA.
Digital data from the keypad interface and telemetry (modes only) is transferred
through a data bus and analog signals (MECG, FECG, Ultrasound, TOCO) from the
telemetry are separately routed through the main PWA to the DSP for processing
similarly to the existing front panel patient data.
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