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Model 3820
Universal Counter
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Version 3.0
Software for Windows Vista
Now Available - Free upgrade for existing users! |
The Model 3820 Universal Counter allows up to eight measurement outputs
to be generated as a function of time, these being:
- Frequency
- Average period
- Average duty cycle
- Average pulse-high time
- Average pulse-low time
- Event counts
- Logic level (input voltage above/below threshold)
- Time
The counter is principally intended for counting bi-level signals,
which have two distinct voltage levels and clean transitions between them.
Such signals include those generated by all common logic families used in
electronic circuits, as well as most Trigger or Sync outputs of common
test instruments. Measurements are updated at one of five user selectable
intervals in the range 5 ms to 100 ms. the module is powered and
controlled directly from the PC’s USB port, so requires no additional
power source. Operation is entirely via software, with no manual switches
or settings.
Two inputs are provided, each connected to a separate discriminator
with adjustable threshold in the range –0.2 V to +0.5 V (–2.0 V to
+5.0 V when used with a x10 probe). Following the discriminators, a
multiplexer selects one of the signals for processing, allowing two
different signals to be measured sequentially.
| The supplied instrument control
software consists of two layers. At the upper level, a simple
Windows dialog application, "SR3820Counter", offers a
convenient panel that allows the input (A, B or one of three
internal test sources) to be selected, an update rate to be
specified and all eight output measurements to be displayed. A
further display area shows one of the measurements in a larger font
size, as well as displaying a graphical trendline display. |
Easy to use SR3820Counter applications software
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Log measured data to file
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The program also supports data logging
to text file of the output measurements, with data being written
directly in CSV (comma separated value) format for easy import to
other programs. The software includes a sub menu where the voltage
input thresholds can be set for the two inputs. |
At the lower level, a
dedicated ActiveX control known as "SR3820Comms" takes
care of all communications to and from the instrument. Two main
modes of operation are therefore possible. Users who simply want to
operate the counter "out of the box" need do no more than
plug it in, install the driver and software, and then use the SR3820
Universal Counter software to control it. Alternatively, when the
counter is to be used as part of a computer controlled test system,
then the user can develop software to control it via the SR3820Comms
ActiveX control. The control eliminates the need for users to write
the low-level code needed to send commands to and receive responses
from the counter, allowing them to concentrate on developing the
higher level program to run their experiments. Typical applications
include:
- Photon counting
- Frequency measurement
- Test and measurement systems implement in LabVIEW where a SIGNAL
RECOVERY 3820 counter can be used at the same time as
instruments from different suppliers.
- Measurement system using scripted web pages (HTML files)
operated via Internet Explorer.
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| The SR3820Comms control can of course also be used at
the same time as other SIGNAL RECOVERY software
ActiveX controls, such as SR3830Comms, allowing sophisticated
systems to be assembled. For example, five APD's (avalanche
photodiodes) could each be connected to the inputs of a model 3830
multiplexer, with the output being in turn connected to the A input
of a model 3820 counter. Using both controls a user-developed
application program could sequentially count the pulses being
generated by each APD.
Both the top level SR3820 Universal Counter software and the
lower-level SR3820Comms ActiveX control include comprehensive
on-screen help files, while examples of how to use the control in
LabVIEW, Visual Basic, VBScript, Visual C++ and Excel are also
supplied.
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Sample Excel Workbook using SR3820Comms
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Specifications
| Input |
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Impedance |
1 MΩ, DC coupled |
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Threshold |
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Direct |
–0.2 V to 0.5 V
in 1 mV steps |
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With x10
probe |
–2 V to 5 V in 10 mV
steps |
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Polarity |
Event counter triggers on
rising edge of signal |
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Sensitivity |
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Direct |
-15 dBm/50 Ω (23
mV rms) at 100 MHz, -10 dBm/50 Ω (0.7 V rms) at 120 MHz |
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With x10
probe |
1 V pk-pk sinewave at
125 MHz |
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Min Input Slew Rate |
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Direct |
200 mV/µs |
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With x10
probe |
2 V/µs |
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Abs. Max Input |
< 50 V DC |
| Frequency
Range |
DC to 125 MHz min, 160 MHz
typical |
| Timebase
Accuracy |
better than 5 ppm/degree
C, 0 to 50 degrees C |
| Reporting
Intervals |
100, 50, 25, 10 and 5 ms |
| Functions |
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Frequency |
0 to 125 MHz |
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Avg Period |
> 8 ns |
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Avg Duty Cycle |
0 to 100%. Measured by
sampling with a 65 MHz clock. |
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Avg Pulse High or Low Time |
> 5ns. Computed from Duty
Cycle and Frequency |
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Events |
0 to 9,999,999,999 counts |
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Logic Probe |
0 = input voltage below
threshold, 1 = input voltage above threshold |
| Indicators |
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USB |
Front-panel LED turns on
during USB communications |
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EVENT |
Front-panel LED turns on when
the input signal is above the threshold |
| USB Connector |
Rear-panel, female USB
connector for connection to the PC or a USB hub |
| USB Cable |
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Supplied complete with 6ft
(1.8m) USB A/B cable |
| General |
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Power Requirements |
<500 mA @ +5 V DC,
supplied via USB |
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Dimensions |
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Width |
5½" (134 mm) |
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Depth |
4½" (114 mm) |
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Height |
1¼" (32 mm) |
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Weight |
9.9 oz (280 g) |
| Software |
A CD containing
the full applications package for 32-bit Windows XP SP2/SP3 and
Vista allowing threshold and input to be adjusted, and measurements
to be displayed and saved is supplied with each unit. SR3820Comms
ActiveX control also included for use with compatible programming
languages, and examples provided of its use in C++, VisualBasic,
VBScript, LabVIEW and Excel. Both top-level and ActiveX software
includes on-screen help. |
Already using a model 3820?
Version 3.0 of the software is fully compatible with 32-bit versions of
Windows XP and Vista. It includes a new USB driver, updated ActiveX
control and new help files for both the counter software and the control.
The Universal Counter application software generates data logging files
that are compatible with those created by the older package, so in most
cases users of the older software will get better performance by
completely uninstalling it and replacing it with the new programs, which
are available free of charge by clicking the link below.
Download Software
The SR3820Counter, SR3820Comms ActiveX control, and sample files are
available by download from this website
Product support and upgrades are automatic and free of charge to
existing users of the model 3820 Universal Counter. If you have already
purchased the product and installed the software then you can simply
download and install any later software version by clicking the link
below.
To check if you need to upgrade, see the product version number on the
distribution CD or in the program's "About" box and verify if
this matches the version given below. If it is a lower number then you
should upgrade.
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is
a trademark of AMETEK, Inc.