Anfatec eLockIn 203, Руководство пользователя

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R oll-Off or Slope
[ LockIn / Input / Slope ]
This parameter is related to the order of the low pass filter. We can select among
6 dB/oct, 12 dB/oct and 24 dB/oct. The 6 dB/oct selection equals a low pass filter slope
of 1
st order, while the 12 dB/oct and 24 dB/oct equal the 2 nd and 4 th order, respectively.
Config
[ LockIn / Input / Config ]
This entry switches between the different input modes, if available from the model
configuration.
Mode Description
A
The input A is amplified in two different stages and given to the two ADC
inputs of the digital lockin amplifier design, simultaneously. This reduces the
noise. The 4-phase lockin evaluates two phases at the 1
st harmonic and two
phases at any higher harmonic.
A-B
Models
203,
204/2,
205/2
The two inputs A and B are amplified separately in a 1 st stage. Then, the
difference between them is built electronically by a differential amplifier. The
2
nd amplification stage is applied to this difference and fed into the input
ADC2. The lockin measures two phases at the 1 st harmonic and two phases
at any higher harmonic.
A&B
Models
203,
204/2,
205/2
The two inputs A and B are amplified separately and fed into the two inputs
ADC1 and ADC2. One measures with two phases at the input A and with two
further phases at the input B. Both inputs operated at the same frequency
(1
st or higher harmonic) with the same input amplification (input gain).
I
current
input
Switches to the current input, if available. In this input type, only two
amplification stages are available. Thus, 0.1 V and 1 V input range equal
each other.
No matter which input mode in chosen, the
Time
Constan
t in [ LockIn / Input /
Time ] and the
Slope
in [ LockIn / Input / Slope ]
apply to all measured
signals (all four phases).
3.2.2 R
EFERENCE
O
UTPUT
[ L
OCK
I
N
/ R
EF
]
The internal digital sine stream is built from a look-up table. The building process
depends on three parameters: The main frequency, the phase and the harmonic. The
generated reference output signal relates to this internal stream through these three
parameters. In addition to that, the reference output has the amplitude as an
independent parameter.
Reference Output Amplitude
[ LockIn / Ref / Uac ]
The reference output is a sine signal. The parameter Vac is its RMS amplitude.
Reference Output Frequency
[ LockIn / Ref / f [Hz] ]
The frequency selected here is the reference frequency f
Ref
of the reference output and
middle frequency of the lock-in amplifier. The analysis of the signal is done at the h th of
its harmonics f
m
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