HP 54520 Series - Page 93

Figure 5-6
Trigger
Pattern Trigger Mode
Pattern Softkey
The pattern softkey is not labeled, but it is the third softkey from the top.
The pattern softkey defines a 4-bit pattern for which the oscilloscope
searches. The positions correspond to the channel or trigger inputs, as
shown in figure 5-6. For example, on 4-channe! models, the left-most bit
corresponds to channe] | and the right-most bit corresponds to channel 4.
On 2-channel models, the left-most bit corresponds to channel | and the
right-most bit corresponds to the external trigger input.
If the pattern is set to all X’s (don’t care), a trigger event will not occur
because a trigger event is not defined. Any trigger source that you are not
using as part of the qualifier pattern should be set to a don’t care to make
sure that the source does not cause false triggering.
You can set the trigger level and noise reject independently on each source in
the edge menu. For example, you can set the trigger level on channel 1 toa
TTL high and the trigger level on channel 2 to an ECL low. However, all of
the channels are set to de coupling for all of the trigger modes except for the
edge mode.
Sasa2029