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Subject to change without notice
CombiScope
®
The oscilloscope HM2008 combines two oscilloscopes in one:
an analog oscilloscope and a digital oscilloscope. With a touch
of the Analog/Digital pushbutton you can switch between ana-
log and digital mode (oscilloscope operation). To avoid long
explanations, the terms analog and digital mode are used in
the following text.
In contrast to analog mode the advantages of digital operation
are:
– Capture and storage of single events
− No flicker with very low frequency signals
− Even very low frequency signals can be displayed as a com-
plete curve.
– Fast signals with a low rep rate or low duty cycle can be
displayed at high intensity
– Due to the digital storage of all signals they may be easily
documented and processed.
The analog mode offers an unsurpassed faithful signal display
as conversion errors can not occur. With the combination of
analog and digital oscilloscope, HAMEG enables the user to
select the most suitable mode for the specifi c measurement.
The HM2008 contains two 8 bit fl ash A/D converters with a
maximum sampling rate of 1 GSa/s each. With the exception of
single event capture mode and DUAL with a maximum sampling
rate of 1 GSa/s, the maximum sampling rate in single channel
mode is 2 GSa/s. The sampling rate, which depends on the time
base setting, is displayed by the readout. These conditions apply
to real time sampling.
If random sampling is chosen even higher sampling rates (20
GSa/s) can be realised. This sampling mode assumes repetitive
signals without any change. Under the infl uence of signal jitter,
noise, phase or amplitude changes, random sampling causes
faulty signal displays.
The signal display can be performed with dots or vector display
(with or without automatic interpolation). All captured and stored
signal data can be transmitted via RS-232, USB, Ethernet and
GPIB interface for documentation purposes.
Signal display modes
In digital mode signals can be recorded and displayed in dif-
ferent modes:
1. A trigger dependent repetitive recording (menu: ACQUIRE)
with Yt display.
Refresh:
Readout display “rfr” (real time sampling)
Random
sampling:
Readout display “rfr”
both recording modes with the sub modes:
Envelope:
Readout display “env”
Average:
Readout display “avg#x”
(x represents a number between 2 and 512)
2. Continuous trigger independent recording (menu: ACQUIRE)
with a signal display moving (rolling) from right to left:
Roll:
Readout display “rol”
3. Trigger condition dependent single event recording with Yt
display:
Single:
Readout display “sgl”
4. Trigger independent continuous recording (menu: VERT/XY)
with XY display:
XY:
Readout display “XY”
5. XY display of previously in Yt mode recorded and with STOP
overwriting protected signals:
XY:
Readout display “XY”
In SINGLE, REFRESH, ENVELOPE and AVERAGE mode a trigger
event starts the recording while ROLL and XY mode recordings
are trigger independent.
In REFRESH and its sub modes ENVELOPE and AVERAGE the
ins trument behaves as an analog oscilloscope. The trigger cir-
cuit starts a recording, overwriting the previous recording from
the left to the right side of the screen. After the recording has
been fi nished, the next trigger event starts the same procedure.
This can also be caused in automatic trigger mode without an
applied signal by the automatic circuitry. Then only the trace (Y
POS. setting) is recorded.
In contrast to automatic trigger mode, in normal trigger mode
the automatic system is switched off and consequently only a
trigger signal can start a recording. Unlike analog mode where
the screen is dark until a trigger signal starts the time base, in
store mode the last recorded signal remains visible as long as
no new recording is triggered by an input signal.
SINGLE mode (“sgl”) enables the capture of one time events.
The recording is started by selecting “Single” called by pressing
the (Trigger) MODE pushbutton, so that the RUN/STOP push-
button fl ashes. After a trigger event occurred and the recording
is completed, the RUN/STOP LED is lit continuously. “Single”
automatically switches over to normal triggering, to avoid un-
wanted signal display caused by the trigger automatic.
The RUN/STOP pushbutton can also be used to stop a current si-
gnal recording and to undo it by pressing the pushbutton again.
The voltage height that is required for normal triggering can be
determined by the trigger point symbol position, the 0 Volt trace
position (indicated by a ground symbol in the screen centre) and
the Y defl ection coeffi cient in the following way:
Determine the vertical distance of the trigger point symbol and
the ground symbol (e.g. trigger point symbol 2 cm above the
ground symbol) and multiply with the current Y defl ection coef-
fi cient that includes the probe attenuation: 2 (cm) x 1 (Volt/cm) x
10 (10:1 probe). This means that depending on the slope setting
a voltage cr20 Volt causes triggering.
Vertical resolution
The dot density in each operation mode is 8 bits = 28 = 256 dots
displayed over a height of roughly 10 divisions. The instrument
is adjusted for 25 dots per division. This eases processing and
cursor measurement.
C o m b i S c o p e
