Hameg CombiScope HM2008 Manual Download

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Subject to change without notice

18.1 Measuring mode

If this function is chosen, one of the measuring modes shown
in the selection box list can be selected with the INTENS knob

options. In most cases the unit related to the measuring

mode will be displayed automatically. The measuring function
is self explanatory.
When “Signal Freq.“ (signal frequency) and “Signal Period“
are measured in digital mode, the measuring result originates
from the signal data and not from the trigger signal. Thus the
time coefﬁ cient must be set such that a minimum of one signal
period is displayed.

18.2 Respect

18.2.1

“Respect Tr“ indicates that the trigger signal is used for

measurement. If e.g. the signal applied at channel 1 serves
as trigger signal (internal triggering) the displayed measuring
value is related to this signal.

18.2.2

CH1 or CH2 indicate the trigger signal source. If the

INTENS knob

symbol is displayed, the source can be chosen

with the INTENS knob

18.3 Off

Pressing the function key “Off“ switches AUTO MEASURE and
the menu display off.
The menu can be left without switching AUTO MEASURE off by
pressing the MENU OFF pushbutton

LEVEL A

B – FFT Marker

(knob)

The knob function depends on Yt or FFT mode.

19.1 Yt mode

The LEVEL control allows you to set the trigger level, i.e. the
voltage or signal level, which will generate a trigger to start
the time base whenever the signal passes that level. In most Yt
modes the readout will show a symbol the vertical position of
which indicates the signal point which will trigger. The trigger
symbol will be ”parked“ on the second graticule line from the
bottom in those modes where there is no direct relationship
between trigger signal and trigger point.

In normal trigger mode the LEVEL control will move the trigger
symbol anywhere. In automatic peak to peak detection mode, the
level can only be selected between the signal’s peak values.
The movement of the trigger symbol is vertical only. The range of
this symbol is limited so that it will not overwrite other readout
information. As soon as the trigger symbol leaves the graticule
its form will change, this change indicates in which direction
the trigger symbol left the graticule.

Analog mode only: Depending on the time base mode the LE-
VEL control will affect the time base A or B triggering. Press
the HOR VAR pushbutton

in order to select the time base

mode in the ”Time base“ menu. In ”Search“ mode (alternate
time base mode) the last trigger level setting for time base A
will remain valid (graticule left) if time base B is switched to
triggered mode. (Menu ”Time base“: set B trigger to positive or
negative slope). Thereafter the LEVEL A/B control will control
the time base B trigger, a second trigger point symbol will be
shown and marked with ”B“.

19.2 FFT mode

The FFT control will move the marker („X“ Symbol) over the
frequency range. The marker follows the displayed spectra.
The readout additionally displays the frequency on which the
marker is set (“MX:xxxMHz“) and the level („MY:xxxdB“ respec-
tively ”MY:xxxV“).

MODE

(pushbutton)

Preliminary note!

The pushbuttons MODE

, FILTER

and SOURCE

refer

to the trigger unit. In XY mode these pushbuttons are without
effect as XY displays are untriggered.

Pressing this pushbutton will open the ”Trigger“ menu, where
Auto, Normal, Single (sweep triggering) can be selected. Choo-
sing ”Slope“ will allow trigger on any signal shape. For video
signals select ”Video“ and press the pushbutton FILTER

order to ﬁnd a choice of special trigger modes for composite
video signals. In digital mode also ”Logic“ will be offered, allo-
wing trigger on logic signals. The explanations can be found
in: FILTER

and SOURCE

20.1 Auto (trigger)

Automatic triggering (Auto) is active if the NORM display

not illuminated. In ”Auto“ the analog time base or signal capture
(digital mode) will be periodically started even if there is no
signal or when no triggers are generated because the settings
are incorrect. Signals of

20 Hz can not be triggered as the

automatic start will have occurred before the signal arrived.
Automatic triggering is possible with or without peak detection.
The LEVEL A/B

control will be active in both modes.

In peak detection mode the range of the level control is limited
to the peak to peak voltage of the signal. Without peak detection
any level can be set. If the trigger level is set such that no trig-
gers are generated the automatic triggering will nevertheless
start the time base. The signal will thus remain visible but will
be untriggered.

Automatic peak triggering is active if automatic triggering
(MODE: AUTO) is chosen in combination with the trigger FILTER
setting AC (trigger coupling). The active mode will be shown
by the behaviour of the trigger point symbol when turning the
LEVEL knob.

20.2. Normal (trigger)

If the NORM LED

lights up, normal triggering was selected.

In normal trigger mode both the peak detection and the au-
tomatic time base start will be disabled. Hence if there is not
sufﬁcient trigger signal, the screen will remain dark in analog
mode. In digital mode signal capturing will also stop unless the
roll mode was selected.

C o n t r o l s a n d R e a d o u t

FFT-
Marker

VAR

x10

TIME / DIV

SCALE

VAR

X-POS

LEVEL A/B

50s

2ns

LC/AUX