Anfatec eLockIn 203 User manual

eLockIn 203
dual input 4-phase DSP lock-in amplifier
models produced after 01/2014
– Manual –
L
L CK CK-I -IN N A AMPLIFIER MPLIFIER 10 10 m mH HZ Z T T 250 250 k kH HZ Z
S
SPECTRUM PECTRUM A ANALYZER NALYZER
D
DATA ATA A ACQUISITI N CQUISITI N
D
DIGITAL IGITAL SCILL SC PE SCILL SC PE
November 2014
Anfatec Instruments AG
Melanchthonstr. 28
08606 elsnitz /V.
Tel.: [phone]
Tel.: [phone]
http://www.anfatec.de
email: mailb[email protected]
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TABLE OF CONTENTS
1 Introduction..................................................................................................................5
1.1 General Functions..................................................................................................5
1.2 Specifications eLockIn203.......................................................................................7
1.2.1 Lock-In Amplifier...........................................................................................................7
1.2.2 scilloscope:................................................................................................................9
1.2.3 AUX In:........................................................................................................................9
1.2.4 AUX ut:......................................................................................................................9
2 Lock-In Basics..............................................................................................................10
2.1 Lock-In Amplification............................................................................................10
2.2 Mathematical Description......................................................................................10
2.3 Characteristical Curves of a Lock-In Amplifier.........................................................12
2.4 Noise Measurements.............................................................................................13
2.5 Example: Electrical Force Microscope.....................................................................14
3 Users manual...............................................................................................................16
3.1 Technical introduction...........................................................................................16
3.1.1 Front Panel.................................................................................................................16
3.1.2 Screen rganization....................................................................................................17
3.1.3 The Menu Tree...........................................................................................................18
3.1.4 Rear Panel..................................................................................................................20
3.2 The LockIn Menu [ LockIn ]..................................................................................20
3.2.1 Input Settings [ LockIn / Input ]..................................................................................20
3.2.2 Reference utput [ LockIn / Ref ]................................................................................23
3.2.3 Display Settings [ LockIn / Display ].............................................................................24
3.2.4 AUX ut [ LockIn / ut ].............................................................................................25
3.3 The Spectra Menu [Spectra]..................................................................................26
3.3.1 Run/Stop [ Spectra / Run ] or [ Spectra / Stop ]...........................................................26
3.3.2 Display [ Spectra / Display ].........................................................................................26
3.3.3 Acquire [ Spectra / Acquire ]........................................................................................27
3.3.4 Save [ Spectra / Save ]................................................................................................28
3.4 scilloscope [ Scope ]...........................................................................................28
3.4.1 Run/Stop [ Scope / Run ] or [ Scope / Stop ]................................................................28
3.4.2 Display [ Scope / Display ]...........................................................................................29
3.4.3 Acquire [ Scope / Acquire]...........................................................................................29
3.4.4 Save [ Scope / Save ]..................................................................................................29
3.5 Measure [ Measure ].............................................................................................29
3.6 Setup [ Setup ]....................................................................................................30
3.7 Handling of parameter settings.............................................................................31
3.8 FTP Data Access...................................................................................................31
3.9 HTTP Web Access.................................................................................................31
3.10 Known Problems.................................................................................................32
4 Remote Control............................................................................................................33
4.1 General Accessing via CGI- Interface.....................................................................33
4.1.1 Technical Requirements...............................................................................................33
4.1.2 Authentication............................................................................................................33
4.1.3 Sending Key Codes to the eLockIn...............................................................................34
4.1.4 Setting Any Values......................................................................................................36
4.1.5 Examples For Keycode peration.................................................................................40
4.1.6 Retrieving Screenshots................................................................................................41
4.1.7 Retrieving Channel Values...........................................................................................41
4.1.8 Get Internal Settings and Status Information................................................................41
4.1.9 Example Program: LockInRemote.................................................................................42
4.2 Use CGI-Functions via Web Browser......................................................................44
4.3 Exported functions of the eLockin.dll......................................................................44
4.4 Remote by Matlab................................................................................................45
4.5 Remote control for the eLockIn in LabView............................................................46
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4.5.1 TCP/IP access by LabView...........................................................................................46
4.5.2 DLL based access by LabView......................................................................................48
5 Software-Update..........................................................................................................50
6 Revision History...........................................................................................................51
6.1 Manual Revisions..................................................................................................51
6.2 Hardware Revisions..............................................................................................51
6.3 Software revision..................................................................................................51
7 Appendices..................................................................................................................52
7.1 Schematic diagram of the signal paths...................................................................52
7.2 Diagram of the lockin amplification paths...............................................................53
7.3 Frontpanel Dimensions.........................................................................................54
7.4 Instrument Specific Test Sheets............................................................................55
7.5 Preamplifier Connector Pinout...............................................................................56
7.6 CE Certificate.......................................................................................................57
7.7 Traceability Chart.................................................................................................58
The manual uses the following style declarations to visualize certain meanings:
This style describes shortly, how to reach a parameter in the
menus. The list of buttons to be pressed is written usually in
these brackets: [ ... ] .
Parameter names changeable in the menus are written in this style.
The parameter values have this style.
In contrast to parameters which are hidden behind some menu entries, the
main menus as LockIn, Measure, ... are directly accessible by buttons, which
are written in this style. Also, file names used for the remote programming
are written in this style.
Examples are written like this.
otes to the user that might be helpful are shown in this style.
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Copyright 2002-2014 Anfatec Instruments AG. All rights reserved. Anfatec, AMU and
eLockIn are trademarks of Anfatec. ther product and brand names may be trademarks
or registered trademarks of their respective owners.
Anfatec Instruments AG assumes no responsibility for any damage or loss resulting from
use of this handbook.
Anfatec Instruments AG assumes no responsibility for any damage or loss resulting from
use of the software. Anfatec Instruments AG assumes no responsibility for any damage
or loss by deletion of data as a result of malfunction, dead battery, or repairs. Be sure to
make backup copies of all important data on other media to protect against data loss.
Using any part of the software indicates that you accept the terms of Anfatec Software
License Agreement.
Manual date: 11/14/14
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1 INTRODUCTION
1.1 GENERAL FUNCTIONS
The eLockIn203 is a versatile scientific instrument that supports the following functions:
LockIn Amplifier
Digital scilloscope
Spectrum Analyzer
Data Acquisition
The instrument works as a stand-alone device with a 5.6 inches TFT display. Its internal
functionality is best described with the following overall schematics:
The two input signals A and B can be used in three different input modes:
Mode A : the input A is given to both AD-converters simultaneously.
Mode A-B : after a first amplification, the difference between A and B is formed
electronically. The resulting signal A-B is given to both AD-converters
simultaneously.
Mode A & B : the two inputs are amplified separately with the same amplification
factor and feed independently into the two AD-converters.
Note: When the H a r m onic is set to 1 and the input c o n f i g uration
A-B or A is chosen, the signals Xn, Yn, Rn and Phin are displayed as
X, Y, R, and Phi and equal the results provided as X1, Y1, R1 and Phi1.
The different stages of input amplification and switching between the three input modes
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Figure 1: Schematic diagram with the basic components of the lock-in amplifier (see page
52).

The signals which have to be analyzed run through analogue amplification stages whose
3 dB bandwidth is 250 kHz. They are converted with a 40 MHz sampling rate. The whole
lock-in analysis is realized in a fully digital design. The digital oscillator output signal is
D/A-converted with a rate of 40 MHz and amplified to provide the reference output for
the user.
All internal signals marked in green (output) or blue (input) color are handled with
approx. 40 kHz rate, so that the shortest time constant available in the system is 25 µs.
Further 96 bit digital low-pass filters extend the time constant range up to 1 ks. The
user has access to all lock-in inputs and lock-in outputs as well as to 8 additional
analogue input channels AUX-In which are converted with 24 bit @ 40 kHz.
ut of this signal variety, the user selects 4 signals in order to display them in acquired
frequency spectra or in the oscilloscope screen.
Besides these general functions, the eLockIn203 provides:
32 Megabytes of internal data storage
USB connection for external flash memory (USB flash drive)
Remote Control via Ethernet access
HTTP-Server
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Figure 2: Schematic of the input stage describing the switching between the three input
modes A, A-B and A &B as well as the position of the input amplification stages in order
to realize the three different input gains.

1.2 SPECIFICATIONS ELOCKIN203
1.2.1 LOCK-IN AMPLIFIER
General
Digital Quad-Phase Lock-In Amplifier
Dynamic Reserve 135 dB
Noise (single ended A) < 5 nVrms/Hz0.5 @ 100kHz
Remote Control Ethernet
Time Constants 0.1 ms ... 1 ks
Full Scale Sensitivity 10 nV ... 10 V in 1-2-5 sequence
Phase Resolution 0.0001°
Signal Input
Voltage Input (A and B) BNC, single-ended (A) or dual
(A&B) or differential (A-B)
Input Coupling DC or AC (f -3dB = 2 Hz)
Damage Threshold +/- 12 V
Full Scale Input Ranges ±3.6 Vrms, ±360 mVrms, ±35 mVrms
Roll- ff 6 dB/oct, 12 dB/oct, 24 dB/oct
Time Constants 0.1 ms to 1 ks in1-2-5 steps or in
Sync-Mode:
1/f to 200/f in 1-2-5 steps
Gain Deviations between Dynamic Ranges: < 1 %
Gain accuracy @ 22°C ±(0.0004 % of range
+ 0.5 % measurement)
Input Impedance ~ 1 MΩ || 10 pF
Bandwidth dc to 250 kHz
Input Noise @ Uout = 0 V, τ = 1 ms with 50 Ω @ input
@ 100 kHz, high dynamic < 300 nVrms/Hz0.5
@ 100 kHz, normal dynamic < 30 nVrms/Hz0.5
@ 100 kHz, low dynamic < 5 nVrms/Hz0.5
Harmonic distorsion - 80 dB
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Current Input (Optional)
Current Input (optional) BNC (for A-input, only)
Input Coupling DC
Damage Threshold 0.12 mA
Full Scale Input Ranges ± 350 nArms, ± 3.5 µArms
Input amplifications 1 MΩ
Bandwidth dc to 1 MHz
Current Input Noise @ Uout = 0 V, τ = 1 ms
@ 100 kHz, < 1 pArms/Hz0.5
Reference Output (for access to the TTL Ref. output see Appendix)
Internal scillator 10 mHz .. > 250 kHz
Internal Frequency Resolution 3 mHz
Frequency Accuracy +/- 50 ppm from 0 °C to 70 °C
Reference utput Voltage < 0.1 mVrms ... 7 Vrms
utput Noise @ Uout = 1 mVrms, τ = 1 ms
@ 100 kHz < 230 nVrms/Hz0.5
Reference Input
Frequency Range 1 Hz .. 250 kHz
PLL Locking Time < (100 ms+ 10 Cycle)
Phase Error < 4 deg @ f = 1 kHz
Input Amplitude TTL or sine signal > 100 mVrms
Input Impedance for TTL 1 MΩ
Input Impedance for sine 1 MΩ (small signals)
1 kΩ (large signals)
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1.2.2 OSCILLOSCOPE:
Available Channels
Lock-in channels of 1st input RA, ϕΑ, XA, YA
external A/D-channels AD1 to AD8
internal data channels f, Uac, In
internal D/A-channels DA5 to DA8
Lock-in channels of 2nd input RB, ϕΒ, XB, YB in “A&B”
Rn, ϕn, Xn, Yn in “A” & “A-B”
Mathematical Channel Noise
Maximum Number of Simultaneously
Displayed Channels 4
Sampling Rate 39.062 kHz
1.2.3 AUX IN:
Number of Available Channels 8
Input Range ± 10 V
Sampling Rate 39.062 kHz
Resolution 24 Bit
1.2. AUX OUT:
Number of Available Channels 8
utput Range ± 10 V
Sampling Rate 156 kHz
Resolution 24 Bit
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2 LOCK-IN BASICS
2.1 LOCK-IN AMPLIFICATION
The lock-in amplifier is a measuring instrument for extracting and amplifying low signals
from noise by means of a correlation analysis. For this method, it is necessary to know
about the time dependence of the signal to be measured. Practically this signal is
modulated at a certain reference frequency ω
ref
and the resulting frequency spectrum is
simultaneously analyzed at ω
ref
. For analyzing the input signal the lock-in amplifier
transforms the time-dependent signal at ω
ref
into the frequency domain and averages it
during the time τ. In other words, the lock-in amplifier can be described as a narrow-
band amplifier with the center frequency ωref and a bandwidth that is determined by the
time constant τ.
A schematic diagram with the basic components of the lock-in amplifier is shown in
Figure 1 on page 5. First of all the received signal is amplified and digitized. Divided into
two separate channels, the signal is multiplied by the mentioned reference signal (with
frequency ω
ref
) and the 90° phase-shifted reference signal respectively. The reference
signal is generated with the lock-in's digital oscillator. An additional implemented phase
displacement Ψ enables to compensate phase differences
caused by the measuring equipment. After multiplication, the
resulting signals are low-pass filtered and provide now
information about the real part X and the imaginary part Y of
the analyzed signal relating to the phase position of the
reference signal. ut of them the amplitude R as well as the
relative phase shift φ are calculated.
2.2 MATHEMATICAL DESCRIPTION
In this chapter, a short mathematical description of the multiplication and integration
steps as the key procedures of a digital lock-in amplifier is given.
For instance, one tries to analyze the noisy signal s ( t ) that depends on a value v ( t ). v ( t )
itself may consist of a constant part v0 and an additional periodic time-dependent part
with the amplitude v1 and the frequency ωref :
vt = v0v1cosref t
. The latter
term modulates the analyzed signal amplitude
svt
.
Then,
svt
can be developed into a Taylor series:
sv0v1cosref t = ∑
k=0
∞
skv0⋅v1
k
k!⋅coskref t
(1a)
with the derivatives
skv0 = dks
dvk
v=v0
k∈ ℕ
. (1b)
Inside the lock-in amplifier
svt
is multiplied by the reference signal with frequency
ωref and integrated over the time τ. That means, in order to determine the value of s(t)
at the time t, all measured values in the past time interval τ have to be taken into
account. Therefore τ should be a multiple of 2π/ ω
ref or bigger because it should contain
at least one period of oscillation to receive correct results.
Beside the modulation at ωref, modulations of s(t) at the frequencies m·ωref with m = 1, 2,
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
R
X
Y

... (1st, 2nd, ... harmonic) are expected. For that reason the lock-in amplifier calculates
the following Fourier components S(m·ωref) in the frequency domain from the input
signal s(t) in the time domain:
Sm⋅ref  = 1
∫
−/2
/ 2
svt⋅e−i mref tdt
. (2)
Together with equation (1) one receives the desired dependency of the measured signal
on the value of v0 at the frequencies m· ω
ref:
Sm⋅ref  = ∑
k=0
∞
skv0v1
k
k ! Km
k
(3a)
with
Km
k=1
∫
−/ 2
/ 2
coskref t⋅e−i m ref tdt
. (3b)
Although the factors
Km
k
converge to zero for k to infinity, some factors remain
different from zero. Series elements of the nth order are also negligible if the
corresponding nth derivative of s ( v0 ) is negligible, too.
The factors
Km
k
for the first four harmonics are shown in the table below:
k =
m12345678910
1
2
3
4
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1
2
3
8
5
16
35
128
63
256
1
1
15
6
7
32
105
512
1
8
5
32
21
128
21
128
1
16
3
32
7
6
15
128

2.3 CHARACTERISTICAL CURVES OF A LOCK-IN AMPLIFIER
For filtering different information out of a received signal the corresponding frequency
ranges ought not to overlap. The following experiment shows how small the difference
between the frequencies should be that they can be analyzed independently:
A sinusoidal signal with a frequency of 100 kHz and an amplitude of 20 mVrms is fed in to
the input of the lock-in amplifier. By sweeping the lock-in's reference frequency ωref
around 100 kHz the frequency spectrum of the input signal is analyzed. In Figure 3, the
output of the lock-in amplifier is plotted in dependence on ωref for different values of
damping (Roll- ff = 6 dB/octave, 12 dB/octave and 24 dB/octave). The time constant τ
has been kept constant.
For a damping of 6 dB/oct, the measured amplitude at 95 kHz drops to approximately
1 % regarding to the maximal value at 100 kHz. For 24 dB/oct, the amplitude at 95 kHz
is practically not measurable. So the curves show that the lock-in amplifier uses a very
narrow frequency band for signal detection.
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Figure 3 utput signal of a lock-in amplifier for a single frequency input signal of
100 kHz and 20 mVrms amplitude at the input. The time constants have been kept
constant.
Signal: 100 kHz, 20 mV Amplitude
Roll Offs:
6 dB
12 dB
24 dB
100 k5 k0 k85 k
102
103
104
105
106
105 k 110 k 115 k
Frequency [Hz]
Amplitude [nV]

2. NOISE MEASUREMENTS
Lock-in amplifiers are capable to measure noise. They detect a signal at a certain center
frequency ωref with an equivalent noise bandwidth. For a Gaussian noise, the equivalent
noise bandwidth of a real low pass filter is the bandwidth which passes the same
amount of noise as a perfect rectangular filter with the equivalent noise band width.
The equivalent noise bandwidth of the eLockIn is determined by the time constant
and the slope of the used Butterworth filter. It is calculated by
Bn=∫0
∞1
12n d
. (4)
The normalized Butterworth filter noise bandwidths are:
Filter order Bandwidth / τ
1 1,570796
2 1,110721
4 1,026172
In order to measure noise spectra, the resulting data should be divided by the square-
root of the used bandwidth.
The integrated spectrum is taken with a time constant of 10 ms
and a slope of 4 dB (4th order) – bandwidth factor ~ 1,03. The
related bandwidth is then 1/10 ms = 100 Hz. In order to interpret
the result as noise in units of V/Hz0.5, the spectrum should be
divided by 10 Hz0.5 (= sqrt(100 Hz)).
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2.5 EXAMPLE: ELECTRICAL FORCE MICROSCOPE
In this chapter electrical force microscopy (EFM) is briefly presented as an example for
the application of lock-in amplifiers.
EFM is a related technique to the well-established atomic force microscopy (AFM). Its
special aim is to detect electrical forces to learn something about the electrical
properties of a surface, for example about the local distribution of surface potentials on
electronic devices or different dopant concentrations in semi-conducting materials.
The fundamental experimental setup shown in Figure 4 is based on a conventional
atomic force microscope: In the non-destructive dynamic non-contact mode, an
oscillating metallic tip fixed to a cantilever is scanning over the surface by means of a
piezo scanning device. The distance between tip and sample can be controlled by
monitoring the oscillation amplitude of the cantilever, because its value is influenced by
short-range van der Waals forces. Therefore a reflected laser beam and a position-
sensitive photo-detector are used. A lock-in amplifier analyzes the detector signal at the
cantilever resonance frequency ωr and passes the determined amplitude value to a
feedback control system that re-adjusts the tip-sample distance. The required
displacement of the z-piezo can be recorded as topography signal.
In addition to the topography, EFM detects electrical forces, too. These forces are
proportional to the derivative of the capacitance C of the tip-sample arrangement with
respect to the tip-sample distance z and proportional to the potential difference U
squared:
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Figure 4: Schematic diagram of the EFM experimental setup.

Fel = − 1
2
dC
dzU2
. (5)
A possible voltage dependency of C is neglected in this consideration.
The voltage U contains a direct voltage part UDC and an alternating voltage part UAC :
U=UDC UAC ⋅cos ref t
. (6)
UDC consists of an additional applied bias voltage and, what is especially interesting from
the physical point of view, potential differences caused by different electronic work
functions and charges. For separating the impact of these electrical forces from other
forces (e.g. van der Waals forces), U has to be modulated at the frequency ωref. As a
result of this, the measurable photo-detector signal is modulated, too.
Inserting equation (6) in (5) and using power-reduction formulas of trigonometric
functions one can expect a force between tip and sample at the frequency ωref as well as
at 2·ωref. Figure 5 confirms this prediction: It shows the frequency spectrum of the
cantilever oscillation with clear signals at the mechanical excitation frequency ωr and at
the frequencies of the first and second harmonic of the electrical excitation.
Now two additional lock-in amplifiers (see Figure 4) can be used to analyze the photo-
detector signal at the frequency ωref and 2·ωref simultaneously. The measured amplitudes
of the signals are proportional to the strength of the electrical forces.
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Figure 5: Frequency spectrum of the oscillating cantilever

3 USERS MANUAL
This manual part describes where to find and how to change a parameter. It also gives
an overview of the front panel and rear panel structure. An abbreviation like
[LockIn / Ref / f] means that the user has to press the buttons “LockIn” → “Ref”
→ “f“ one after the other.
3.1 TECHNICAL INTRODUCTION
3.1.1 FRONT PANEL
Connectors / Switches:
In: Signal input of the lock-in amplifier,
Power: Main on/off button of the instrument,
Ref ut: The lock-in amplifier reference output.
Fixed avigation Buttons:
Knob: Use this knob to change the selected parameter fast. When the knob is
turned in a clockwise direction, the selected parameter will be increased. When it is
turned counterclockwise, the selected parameter will be decreased. Use the
pushbutton in the knob to switch between menu meanings.
Up / Down: These two buttons increase / decrease the value of the selected
parameter stepwise.
Left / Right: These buttons move the cursor in the selected parameter input field
one digit to the left or to the right. The digit that can be changed with the Up and
Down buttons is always the marked digit.
Variable avigation Buttons:
Button o. 1 to 5 : Selects the function left besides the button.
Back: Goes one step upwards in the menu structure.
Menu Selection Buttons:
LockIn: This is the control key to enter the LockIn mode. In the LockIn mode,
parameters connected with the LockIn function can be changed. In addition, the
channels to be displayed in the oscilloscope and spectra mode as well as the output
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Figure 6: The front panel.

signal and the scaling of the DA-channels can be modified here.
Spectra: This is the control key for the Spectra acquisition mode. The displayed
channels are selected in the LockIn mode.
Scope: Press this button to turn the instrument into scillos cope mode. The
displayed channels are selected in the LockIn mode.
Measure: This menu provides certain functions which make the usage of the
instrument easier, such as the frequency selection in a recorded spectrum.
Setup: In this menu the user can change some basic setup parameters, such as
the IP address of the device or the warning signal.
ote: When the parameters reach their maximum or minimum value, the
increase or the decrease actions have no effect.
3.1.2 SCREEN ORGANIZATION
The screen is divided into three parts:
the main screen
the menu display and
the parameter display.
While the menu display helps to navigate through the parameter menus, the main
screen contains information, which is specific for the selected mode of the device. The
parameter display provides information, which is usually hidden behind several menu
entries.
The main screen shows:
current values of selected channels in LockIn mode,
acquired data in Spectra mode and scillo scope mode and
system parameters in the Setup mode.
The menu gives access to parameters. The menu trees are shown in the Figures 8 to 10.
Note that each menu entry consists of a name and some have a value.
This menu entry consists of a name “f1 [kHz]” and a value “10.000”. The value can be
changed with the Up and Down functions.
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Figure 7: Screen organization at the example of the LockIn menu.

This entry consists of a name only. It usually leads
to a sub-menu.
3.1.3 THE MENU TREE
The five top base menus are selected with the Menu Selection buttons displayed in
Figure 6 on page 16. The sub-menus are shown in the following pictures:
When [LockIn] is pressed, the first line of the menu structure mentioned in Figure 8
is shown in the menu screen, which means Input in the first line, Ref in the second line
and Display in the third line.
When now Input is selected, the menu items will change to Range in the first, Couple
in the second, Time in the third and Slope in the fourth line. ut of these four items,
the selected item is perceptible from the darker background color. In order to select
another item, press the button right of it once. In order to change a number displayed
below the name, use the Left / Right functions to select the digit and the Up / Down
function to change it.
The corresponding structures of the Spectra and the Scope menus are shown
below:
18 (58)
Figure 8 Menu structure of the LockIn mode.

The knobs Measure and Setup do not provide a deep menu structure. In order to
understand the meaning of each entry in the menus, follow the manual structure
starting with the LockIn menu in section 3.2.
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Figure 9: Menu structure of the Spectra mode.
Dest.
Save
Name
Axis
Color
Type
Offset
Spectra
Run Display Acquire Save
Type
f2 [kHz]
f1 [kHz]
Point
Delay
-> Ref
Figure 10: scilloscope menu called with the Scope button.

3.1. REAR PANEL
The back side panel provides
8 x BNC connectors for the internal A/D converters (-10 V .. 10 V) “Aux In”
4 x BNC for displaying the selected channels scaled as analogue outputs (DACs)
“Display”
4 x BNC for Aux ut DACs “ ut”
2 x BNC Ref-In connector for the reference input (“Ref In 1” for standard PLL,
“Ref In 2” for LoL mode option)
2 x BNC for monitoring the amplified input signals A and B called
“Monitor A” and “Monitor B”
BNC ut for 10 MHz reference clock “10 MHz ut”
BNC ut for TTL reference output “TTL ut”
BNC ut for sine wave reference out on 2nd lockin frequency “Ref2”
LAN (RJ45) network connector for remote control
the 100 -240 V AC power supply (tested from minimum 100 V AC)
3.2 THE LOCKIN MENU
[ L OCK I N ]
3.2.1 INPUT SETTINGS
[ L OCK I N / I NPUT ]
Input Range
[ LockIn / Input / Range ]
This setting changes the input amplification of the lock-in input stage by two hardware
switches controllable from the software. These factors are according to the range value
of “high dynamic reserve”, “normal” and “low noise”. Together with the input
amplifications, dynamic range and sensitivity change. The lower the dynamic range, the
higher the sensitivity is. The strategy for selecting a suitable range is: Choose the
smallest value which is just bigger than the maximum input signal.
Example: When the maximum input signal is 300 mVpp, the “low
noise” input range will yield an overflow. The “normal” and “high
dynamic reserve” input ranges are both possible, but the “normal”
range gives the better sensitivity.
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Figure 11: Rear-Panel of the eLockIn (picture might very from current revisions). The
ground connector above the power supply allows to separate the protective ground from
the housing and thus increase the resistance between them to 1 M hm.