Acqiris U5309A User Manual page 49

Trigger time interpolator and time-stamps
The trigger time-stamp is the trigger arrival time.
The ADC card accurately measures and stores these time-stamps using the information from the on
board Trigger Time Interpolator (TTI). This information is essential for determining the precise relation
between the trigger and the digitized samples of the signal. The TTI resolution determines the
resolution of the trigger time-stamps.
Please refer to Trigger section of your U5309A
Managing time-stamps
The ADC card features a time-stamp counter. In multi-record acquisitions, each acquired record has a
precise time-stamp, given by the time-stamp counter.
The accurate time-stamp of each trigger is given by the sum of the time reference and the time-stamp
counter.
The time reference is configured:
at the first card initialization,
at the last initialization with reset flag = 1,
or when using Set Time function (IVI-C) or writing Time (IVI.NET).
The time-stamp counter is reset each time the time reference is configured.
Parameters
IVI-C
InitialXTimeSeconds: Specifies the seconds portion of the absolute time at which the first data
point was acquired.
InitialXTimeFraction: Specifies the fractional portion of the absolute time at which the first data
point was acquired.
The actual time is the sum of InitialXTimeSeconds and InitialXTimeFraction.
Adding these values in a variable of type double implies a loss of precision.
IVI.NET
StartTime: StartTime is the time between the first valid data point (that is the data point at index
FirstValidPoint) in the waveform and the trigger. Positive values indicate that the StartTime occurred
after the trigger. If StartTime is zero, the waveform is not relative to anything, or the relative measure
is zero, or the waveform is empty.
EndTime: EndTime is the time between the last valid data point in the waveform and the
TriggerTime. Positive values of EndTime indicate that it occurred after the trigger. If EndTime is zero,
there is exactly one data point and the StartTime is zero, or the waveform is empty.
TotalTime: TotalTime is the timespan represented by the valid points in the waveform.
Numerically, it is equivalent to the IntervalPerPoint * (ValidPointCount - 1). It is also numerically the
U5309A User's Manual
5.2 Trigger modes and time-stamps
datasheet for the relevant specifications.
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