HP 54540 Series - Page 90

Trigger
Edge Trigger Mode
Slope Softkey
The slope softkey is not labeled. However, the available selections are
graphic representations of the rising edge and falling edge. The current
selection is highlighted in inverse video. You can set the slope for each
trigger source except line trigger. Slope applies only to the edge mode.
Reject-Coupling Softkey
The reject ~coupling softkey allows you to turn noise reject on or off,
and allows you to select the trigger coupling.
Reject When on, reject increases the trigger hysteresis band, so that it
takes a larger trigger signal to trigger the oscilloscope. When noise reject
is on, it makes the trigger circuitry less sensitive to noise. You can use
noise reject when triggering on noisy signals without the problem of false
triggering. You can set noise reject independently for each trigger
source, the selection also applies to the logic trigger modes.
Coupling Coupling allows you to further condition the trigger signal
independent of the channel conditioning circuitry. Figure 5-3 shows that
the input signal goes through the input signal conditioning before the
trigger coupling path. For example, you can set the channel path to de
coupling and the trigger path to ac coupling. Coupling applies only to the
edge mode.
e dc allows de and ac signals into the trigger path.
e ac blocks out any de portion of the trigger signal and allows ac signals
greater than 7 Hz into the trigger path.
e lfrej (low frequency reject) adds a 50-kHz, low-pass filter to the trigger
path.
Figure 5-3
peneaned