Decg Module Principle; The System Principle Block Diagram - EDAN F9 Service Manual

F9 Fetal & maternal Monitor Service Manual
and R8 to change, one increases the other decreases, and the increment equals to the decrement.
Apply voltage at E1 and E4, change of resistance becomes change of voltage. The formula is:
In the formula, R denotes the resistance of R1 and R8 when there is no distortion (R1=R8).
Amplify the difference between E2 and E3 with an apparatus amplifier, now the change of
pressure has become change of voltage, which is simple for the system to measure.

7.1.4 DECG Module Principle

DECG measuring principle: collect DECG signals through spiral electrode; amplify and filter
them with Front-End circuit; the microprocessor calculates the fetal heart rate; transfer the fetal
heart rate and original wave data to the main control board through serial port.
IUP measuring principle: sense the pressure of inner uterine with the IUP transducer; transform
the pressure signals into electricity signals; amplify and filter them with Front-End circuit; the
microprocessor calculates the pressure; transfer the result to the main control board through serial
port.

7.2 The System Principle Block Diagram

F9 monitor consists of the main control board, fetal monitor (FM) module, DECG module, print
board, power module, key board, LCD and corresponding interface boards. Here is the system
principle block diagram:
Δ
R
=
2
E
+ Δ + −
1 8
R R R
Figure 7-1 Internal circuit in TOCO transducer
Δ
R
− =
( 1 ) 4 (
E E
Δ
2
R R
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Principle Introduction
−
1 ) 4
E E