7451A/7461A/7461P Digital Multimeter Operation Manual
5.8.5 Level Trigger and Delta Trigger
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5.8.5.3 Pre-Trigger Operation
The measurement values before the trigger event can be acquired by using the pre-trigger function only
when the trigger source is set to LEVEL or DELTA.
The pre-trigger setting can be selected from 0%, 25%, 50%, and 75%.
Although the data before the trigger event is stored in the measurement data memory by setting the pre-
trigger, the total data amount cannot exceed the capacity of the data memory. The 7451A/61A stores up to
10000 data and the 7461P stores up to 20000 data.
Data memory in the pre-trigger operation
• Memory store
Example: Sampling count = 1000
Level/Delta selection
Level/Delta detection
First trigger
Measurement end
Valid data
Invalid data
Empty data
• Because the data memory operates as a ring-memory when the level or delta trigger is used,
the measurement is repeated continuously until detecting the level or delta trigger.
• The number of sampling is up to 10000 when the level or delta trigger is used. Even if the
sampling count is set to more than 10000, only 10000 measurements are performed. (7451A/
61A)
As for the 7461P, the number of sampling is up to 16000.
• If the trigger is detected before the pre-trigger count is reached, the number of valid
measurement results in the memory is less than the set sampling count.
Example: Pre-trigger = 75%
The trigger is detected at the 100th measurement
result after the first trigger.
The number of valid measurement results:
100 + 249 = 349
Measurement end
Measurement end
Measurement end
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