Trigger Coupling - Fluke CombiScope PM3370B User Manual

FUNCTION REFERENCE

TRIGGER COUPLING

Description:
Trigger coupling is used to optimize the trigger stability for different signal types.
The filter modes ac and dc are identical to those of the vertical inputs. Refer to
function INPUT COUPLING.
Lf-reject cuts off lower frequencies; triggering occurs on signals between 30 kHz
and full bandwidth.
Hf-reject cuts off higher frequencies; triggering occurs on signal frequencies lower
then 30 kHz. The following figure explains ac, lf-reject, and hf-reject.
Noise 'on' improves trigger stability for noisy signals. By enlarging the trigger gap
(of MAIN TB and DEL'D TB) the triggering becomes less sensitive to noise.
The MAIN TB trigger coupling can be selected in the menu under the TRIGGER
menu key. For DEL'D TB, the menu under the DTB menu key is used; the
selection is possible in 'triggered' mode (ch1, ch2 and ext trig) only.
ac-coupled
0dB
3dB
10Hz
Effect of trigger coupling modes
Presence of trigger level indicators (T-, D-) as a function of trigger coupling and
other oscilloscope settings:
Trigger
coupling
ac
dc
lf-rej
hf-rej
all settings
if level-pp is on
0dB
3dB
FULL
BANDWITH
FREQ.
Vertical
input coupling
dc
dc
dc
dc
ac
lf-reject
FULL
30kHz
BANDWITH
FREQ.
Trigger level indicator
off
on
off
on
on
off
hf-reject
0dB
3dB
30kHz
BANDWITH
5 - 79
FULL
FREQ.
MAT4218