Hioki BT3554-51 - Synchronous Detection

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Synchronous Detection
11.5 Synchronous Detection
The gure below provides an equivalent circuit for a battery. If an
object under measurement include other components other than
pure resistance component, as shown in this gure, synchronous
detection can be used to obtain the e󰀨ective resistance of the object
under measurement. The synchronous detection is also used to
separate faint signals from noise.
E
L
R
1
R
2
C
The synchronous detection is a detection method that can separate
the signal component having the same frequency as the reference
signal’s frequency from a signal. The gure below illustrates a
simplied schematic diagram of the synchronous detection method.
The system consists of the multiply circuit, which multiplies two
signals, and the low-pass lter (LPF), which allows only DC
components of the multiply circuit output to pass.
+1
−1
Non-inversion
amplier
Inversion
amplier
LPF
Low-pass lter
Multiplier circuit
Reference
signal
HIOKI BT3554F961-00HIOKI BT3554F961-00