161
Synchronous Detection
Where the reference signal voltage of the AC current generated
in the instrument is v1, the signal voltage for use in synchronous
detection is v2. These parameters may be expressed by the
equation given below. A phase dierence from vi, due to a reactance
component, is represented as
θ
in the equation for v2.
v1 = A sin
ω
t
v2 = B sin(
ω
t +
θ
)
When synchronous detection applies to both v1 and v2, they are
expressed as follows:
v1 × v2 =
1
2
B cos
θ
−
1
2
AB cos(2
ω
t +
θ
)
The rst term indicates the voltage drop due to the eective
resistance. The second term is attenuated by the LPF. The
instrument exhibits the rst term.
HIOKI BT3554F961-00HIOKI BT3554F961-00
To Next Page
Loading...
