Delay (Gate Trigger)

The measurement hardware starts capturing data when a valid trigger is detected. A valid trigger occurs when the trigger condition (combination of relevant trigger parameters) is satisfied.

Trigger delay adjusts when the hardware captures data. If the delay is zero, the hardware takes data immediately after the trigger event. Trigger Delay may be positive (post-trigger delay) or negative (pre-trigger delay).

Pre-Trigger (negative) Delay

Pre-trigger delay indicates that the measurement hardware should capture a certain amount of data (say, X seconds) before the trigger signal arrives. This is accomplished using sample memory (RAM). When a pre-trigger delay is selected, the measurement hardware stores the last X seconds of data in sample memory until it receives a valid trigger signal. The hardware then uses the stored data as part of the time capture to achieve the pre-trigger delay.

Pre-trigger delay is limited by the amount of sample memory available for the measurement and the sample rate the measurement is using for the acquisition.

Post-Trigger (positive) Delay

Post-trigger delay indicates how long after the trigger signal to start capturing data and is limited by the range of the trigger counter (which counts the time after trigger happens). This parameter is not affected by sample memory.

Delay can be entered in seconds, milliseconds, or microseconds. For pre-trigger delay, enter a negative value (as in -10 ms). For post-trigger delay, enter a positive value (as in 10 ms).

If triggering is not behaving as expected, see Trigger Level and Delay Issues.