29
Subject to change without notice
After MA the next step causes an arrow symbol to be displayed
in the “Mathematics Edit“ menu under item “Edit“. It is a hint
about another submenu described under item 7.2.5.
7.2.5
Operand selection by Constant Editor
In the CW position of the INTENS knob
2
an additional item
”Edit“ and an arrow symbol is displayed. Pressing the associated
function button opens the sub submenu ”Edit Edit“. This enables
you to choose a number, its ”Dec.Point“ (decimal point) and its
”Prefix“ of the ”Unit“, all with the INTENS knob
2
. The unit need
not be selected: it is only shown as a reminder. A constant selec-
ted as an operand will be displayed as a unit in the menu.
7.3 Display
STOP
Attention!
“Mathematics signals“ (MA1 to MA5), “Reference
signals“ (RE1 to RE9) and “Logic signals“ (LC0 to
LC3) cannot be displayed at the same time. Display-
ing “Mathematics signals“ automatically switches
the display of “Reference signals“ and “Logic
signals“ off, and vice versa.
The function ”Display“ is available twice in the menu and may
be switched on or off in any combination. This allows you to
display: no result, one result, or the result of two equations
as signals. The displays will come forward upon leaving the
MATHEMATICS menu. Also the designation of the equation (e.g.
MA2) will be shown. Select the equations to be displayed with
the INTENS knob
2
.
The mathematics signal is automatically scaled, this is indepen-
dent of the graticule, of Y and time base parameters, hence the
scale will not be shown. The measurement of the signal ampli-
tudes must be performed using the CURSOR (V to GND) after
the REFERENCE (e.g. MA2) of the CURSOR to the ”mathematics
signal“ and its scale is established (CURSOR MEASURE
4
pushbutton
>
Cursors
>
reference
>
e.g. MA2). The readout may
then display e.g.: ”V(MA2): 900 mV“.
In combination division and the constant 0, no result will be
displayed. The mathematics function will only be calculated
and displayed if possible. As the calculation is made in real time
conditions, a new calculation requires that the channels are
activated and new valid data are present (e.g. trigger conditions
are met). An error message will not be output.
7.4 Units
Each function ”Display“ will be associated with a function
”Unit“ which can be selected with INTENS knob
2
and will be
attached to the result. This enables you to allocate a unit to
each mathematics curve. In the case of cursor and automatic
measurement related to mathematic curves it will be indicated
by the readout as the source.
8
Acquire
(pushbutton)
(digital mode only, in FFT mode without effect)
This pushbutton opens the menu ACQUIRE which offers these
modes:
8.1 Normal (Refresh) – Capture/Display
In this mode repetitive signals can be recorded and displayed,
as in analog mode; the display shows rfr. The current signal
capture can be stopped (pushbutton lit) or started (pushbutton
not lit) by the RUN/STOP pushbutton
6
.
A trigger will start a new acquisition which will overwrite the
display of the former. The display will remain on screen until
the next acquisition is started by the trigger and causes a new
recording. This mode is available over the full time base range
(50 s/cm to 2 ns/cm).
STOP
Please
note:
At 20 ms and smaller time defl ection coeffi cients
the signal display always starts at the screen left.
After switching to a time defl ection coeffi cient of
50 ms or higher, the capture starts at once but
under these conditions the signal display starts
at the trigger point, which is placed without delay
(Readout: “Tt:0s“) at the screen horizontal center.
The second capture starts at the screen left.
This behaviour is relatively meaningless for small time defl ec-
tion coeffi cients. In the case of high time defl ection coeffi cients
combined with high Post Trigger times, the instrument seems
to show no reaction. The resulting uncertainty can be avoided
by activating the STATUS display (see item 10.4.4 Status Acq.
(acquisition)
The following example describes the long waiting times caused
by the 1 M Byte RAM:
With the time base setting at 50 s/cm and the trigger point set
to the utmost left position by the HORIZONTAL control
27
, the
readout will indicate ”Tt:1.85ks“. This means that 1,600 seconds
must elapse until the trace will become visible at the screen left
and after another 250 s it will have reached the screen centre
(1,600 s + 250 s = 1.85 ks).
After the capture has been completed, the new signal curve
overwrites that previously recorded, after a trigger event started
the capture and the waiting time elapsed.
8.2 Envelope capture/display
Envelope is a special refresh mode, the readout will show
”env“. Also in this mode there must be sufficient signal for
triggering.
In contrast to the refresh mode the results of several captures
will be examined and the maxima and minima stored, the enve-
lope of the signal will then be displayed if it changes in amplitude
or/and frequency. Also any jitter will be shown.
Also in this mode pressing RUN/STOP
6
will stop the
acquisition, indicated by STOP constantly lit. After pressing the
pushbutton again, the formerly stored signals will be erased
and the envelope calculation starts anew. In order to prevent an
accidental turning on of this mode, operating any control which
influences the signal display will automatically switch envelope
off. Because this mode requires many signal repetitions and
acquisitions it is not compatible with single sweep/acquisition.
AUTO or normal trigger modes must be selected.
8.3 Average mode capture/display
This is also a special mode within the refresh mode. Also here
signal repetitions are needed.
The weighting of each acquisition can be selected with ”Ave-
rage“ in the menu, any number between 2 and 512 may be
chosen using the INTENS knob
2
. The readout will show e.g.
”avg#512“.
The higher the number of acquisitions averaged, the lower the
contribution of a single acquisition will be and the longer the
averaging will take. Averaging is a means to increase the ac-
curacy in spite of the 8 bit converters, it is an exchange of time
against accuracy. Noise will be reduced by averaging.
C o n t r o l s a n d R e a d o u t
