10.5 Synchronous Detection System
Given "v1," a reference signal voltage for the AC current gener-
ated in the instrument, and "v2," the signal voltage for use in
synchronous detection, these parameters may be expressed by
the equation given below. θ of v2 shows the phase difference
against v1 and is generated by the reactance.
v1 = Asinωt
v2 = Bsin (ωt + θ)
When synchronous detection is applied to both v1 and v2, they
are expressed as follows:
v1 X v2 = 1/2ABcosθ - 1/2ABcos (2ωt + θ)
The first term indicates effective resistance. The second term is
attenuated by the LPF. The instrument displays the first term.
To Next Page
Loading...
