Triggering; Menu - Rohde & Schwarz Hameg HM8123 Handbuch

TOTAL A
Event (pulses, periods) measurement of the channel A signal.
If the input signal disappears or if the pushbutton HOLD
depressed the measurement will be stopped and the result
frozen. By pressing the RESET
level on the RESET connector
new measurement will be started after the pusbutton
released or after the RESET signal
Gate time
The counter HM8123 totalizes the input cycles until the gate
time set has eclapsed and the trigger conditions selected are
fulfi lled. Thus the effective measuring time can be longer than
the gate time set. The measuring time cannot be smaller than
one period of the signal.
The gate time can be varied between 1 ms and 65.5 s. Operate
pushbutton GATE TIME and enter the desired gate time by
using the 4 arrow keys
numerical keys and the unit buttons (ms
a measurement the GATE LED
selected, the HM8123 inserts a wait time between the mea-
surements to simplify the reading of the display. In this case a
complete measuring cycle will take at least 180 ms. The wait
time can be deactivated by sending WT0 via the interface. To
activate the wait time WT1 has to be sent.
Gate Time : 500 ms
10.0000000 MHz

Triggering

When using the channels A
gering may be selected. The triggering of channel C
is not selectable, signals between 50 mV and a maximum of 5 V
will be automatically triggered.
Automatic triggering
Pressing the AUTO TRIG pushbutton
triggering, the pushbutton will light up. Please note that AC
coupling is mandatory, the pushbutton DC
In this mode the amplitude of the signal is measured, and the
trigger level is set to 50 % of it.
Manual Triggering
If the AUTO TRIG pushbutton
is active. The trigger level has now to be selected manually.
Operate pushbutton LEVEL A
desired trigger level by using the 4 arrow keys
the knob or with the numerical keys
(mV , V ).
The trigger level may be selected in 3 ranges:
Pushbutton Pushbutton
1:10 1:10
off off
on off
off on
on on
Level A : +0.500 V
10.0000000 MHz
pushbutton or by a high
the display will be reset. A
was
switched to low.
and the knob or with the
, s ). During
is lit. If a short gate time is
Ref: INT
or B manual or automatic trig-
signals
will activate automatic
have to be dark.
is dark, manual triggering
or LEVEL B and enter the
and the unit buttons
Triggerlevel
–2,000 V .... + 2,000 V
–20,00 V .... + 20,00 V
–20,00 V .... + 20,00 V
–200,0 V .... + 200,0 V
Ref: INT
Optimum triggering is obtained by setting the trigger level to
about 50 % of the peak-to-peak amplitude of the input signal.
is In manual mode proper triggering can be checked by the trig-
ger indicators and
follows:
LED on continuously:
LED off continuously:
LED blinking:
LED on
Suitable setting of the attenuators
for correct measurements. With too much attenuation the
residual noise of the input signal comparator will affect the
result. With too little attenuation or if the input signal is too
large the input stage may be overdriven which lead to erroneous
measurements.
With all frequency measurements AC coupling should be used
(below appr. 10 Hz DC coupling will be necessary) together with
as much attenuation as possible. Period measurements should
use DC coupling (pushbutton DC
If the input signal comes from a 50
dance of the HM8123 have to be set to 50
lighted).
The menu is called by pressing the pushbutton SELECT
menus are called from the main menu by using the rotating knob
or the 2 arrow keys
identifi ed by an arrow >. The submenu selected will be opened
by pressing ENTER
arrow keys
enter the value. Pressing ESC
and main menu. The main menu will be left by pressing SELECT.

MENU:

M e n u
control of channels A
Input signal above the trigger
level selected.
Input signal below the trigger
level selected.
Correct setting.
LED off
LED blinking
and is a prerequisite
lighted) if at all possible.
system the input impe-
(pusbutton 50
Menu
. The submenu selected will be
. Parameters are changed by using the 4
or the knob . Pressing ENTER
will return the control to the
STORE / RECALL
REFERENCE
CONTRAST
>
RPM SETTINGS
DISPLAY
CALIBRATE
BEEPER
ABOUT
Subject to change without notice
and B as
0V
. Sub-
will
25