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Technical Description
The RD2 incorporates a photoplethysmographic sensor which uses a sensitive infra-red sensor
to assess, non-invasively, venous incompetency of the lower limb, in response to a calf muscle
exercise.
The electronics for the PPG is enclosed within a pod to which the PPG sensor is attached by a
lightweight straight cable.
4.10 PPG
The data output feature on the FD2-P and MD2-P allows fetal heart rate data to be sent to the
Dopplex Printa in real time.
The MD2-P and RD2 units send fetal heart rate data via the data socket to the Dopplex Printa in
real time OR vascular data to the Dopplex Reporter/Dopplex Printa.
The FD2-P, MD2-P and RD2 will flash the data symbol ( )during information transfer.
The MD2-P and RD2 will output bi directional waveform information in an analogue format via
the data socket.
4.11 Data Output
The D900-P, D920-P, D930-P, FD2-P, SD2-P, MD2-P, FD1-P, FD3-P and RD2 units use a 4 bit
microcontroller to carry out "house keeping" duties, such as driving the LCD display and auto
shut-off timer.
In addition to the 4 bit microcontroller, the FD2-P, SD2-P, MD2-P, FD1-P, FD3-P and RD2 have a
second 8/16 bit microcontroller. This performs FHR processing (including auto-correlation),
controls the data output, probe decoding and waveform generation.
4.12 Microcontrollers
The FD2-P and MD2-P can display FHR in Standard or Smoothed mode. Smoothed mode
FHR uses 8 beat averaging while Standard mode FHR uses 4 beats averaging.
4.13 Standard/Smoothed Mode FHR
The manual mode on the FD2-P and MD2-P can be used when the heart sound can be heard,
but is too weak or noisy for the microcontroller to calculate the heart rate automatically.
In this mode, the Dopplex unit operates as a stop watch calibrated in BPM (beats per minute).
The stop watch is activated by depressing the "Start/Stop" button, 10 heart beats should then be
counted and the button released. The display will then show the average heart rate over the
last 10 beats.
4.14 Manual Mode FHR