Anfatec AMU2.4, Руководство пользователя

Страница: 32 / 70

Variation of time constant :
t = 5 ms, 50 ms, 500 ms
U
ac
= 10 mV
RollOff = 12 dB
Harmonic = 1
Phase = 0°
Coupling: ac
The shorter the time constant,
the higher is the noise of the
detected signal.
Variation of Amplitude
t = 10 ms
U
ac
= 10 mV, 100 mV, 1 V
Smaller excitations cause
smaller signals, so that the
effect of intrinsic noise increases.
frequency [Hz]
1E3 2E3 3E3 4E3 5E3 6E3
1
2
3
4
5
10 mV
100 mV
1 V
AC/DC
t =
20 ms
In addition to this, the effect of an
dc offset on the input signal can
be discussed at this example.
The microphone delivers a signal with
a certain DC offset. With short
time constants, this signal at
f = 0 Hz is not suppressed enough
and thus one finds a strong
signal increase towards
small frequencies.
AC coupling, as shown in the
other measurements suppresses
this effect.
frequency [Hz]
1E3 2E3 3E3 4E3 5E3 6E3
0,5
1
1,5
2
2,5
3
DC
AC
Manual Anfatec PCI-Lockin Amplifier AMU2.4 – Rev. 1.10 dated 30/09/20 Page 32 (70)
frequency [Hz]
1E3 2E3 3E3 4E3 5E3 6E3
0,01
0,02
0,03
0,04
0,05
0,06
5 ms
50 ms
500 ms