MR8740、MR8741_user_manual_eng_20191016H.pdf - 第217页

8.9 Pre-Trigger Settings 205 7 Chapter 8 T rigger Settings 8 Description About pre-trig gering and the recording period (re cording length) Difference between [Pre-T rigger wait] and [T rigger wait] When measurement is s…

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8.9 Pre-Trigger Settings
204
[
This applies to the Memory function, and FFT function only.
By setting a portion (number of divisions or percentage) of the recording length to occur before trig-
gering, the waveform is recorded before as well as after the trigger point.
You can also set the duration of a waveform to be recorded after a trigger point.
Set the position of the trigger point relative to the specified recording length.
There are two setting methods. (Setting by percent and setting by div)
8.9 Pre-Trigger Settings
T
Pre-Trigger Setting
Amount
Recording
Length
T
Pre-Trigger Setting
Amount
Recording Length
Recording Before Triggering
Recording for a Specified Duration
After Triggering
• When all trigger sources (analog, timer trigger, etc.) are disabled (Off), pre-trig-
ger settings are ignored.
• Pre-triggers cannot be set by div with the FFT function.
8.9.1 Setting the Trigger Start Point (Pre-Trigger)
Procedure
To open the screen: Right-click and select [DISP] Waveform screen
1
Select the unit to set the pre-trigger.
Move the flashing cursor to the Pre-trigger.
Select
2
Enter the numerical value.
(When [%] is selected)
With the recording start point as 0% and the recording end point as
100%, set the % for the trigger point.
Select
(When [div] is selected)
With the recording start point as 0div and the recording end point as
the set recording length, set the number of div for the trigger point.
Select
% Settings are by percent. (default setting)
div
Settings are by number of div. For external sampling, set by
number of samples.
-95%, 100%, 95%, 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, 10%, 5%,
2%, 0%
-Recording length (div) to +Recording length (div)
8.9 Pre-Trigger Settings
205
7
Chapter 8 Trigger Settings
8
Description About pre-triggering and the recording period (recording length)
Difference between [Pre-Trigger wait] and [Trigger wait]
When measurement is started, the specified pre-trigger length is recorded. This
period is indicated as the [Pre-Trigger wait].
After the specified pre-trigger length has been recorded, the period indicated as
[Trigger wait] continues until a trigger occurs.
See: "Measurement and Internal Operations" (p.82)
Trigger Point
95% 95% of the recording length is
recorded before the trigger
point
50% 50% of the recording length is
recorded before and 50% after
the trigger point
-95% 95% of the recording length is
recorded after the trigger point
T
Pre-Trigger setting examples
• Trigger events during the specified pre-trigger recording period are ignored. To
enable recognition of such triggers, set Trigger Priority to [On].
See: "8.9.2 Setting Trigger Acceptance (Trigger Priority)" ( p.206)
8.9 Pre-Trigger Settings
206
This applies to the Memory function only.
You can set whether a trigger is recognized (accepted) if trigger criteria are met during this period.
• When pre-triggering is enabled, trigger events are normally ignored for a cer-
tain period after measurement starts (while recording the specified pre-trigger
period).
• This period is indicated on the Status bar as [Pre-Trigger wait].
Description When trigger criteria are met during [Pre-Trigger wait]
Example: When the pre-trigger period is set to 50%
8.9.2 Setting Trigger Acceptance
(Trigger Priority)
Procedure
To open the screen: Right-click and select [DISP] Waveform screen Right-click and select [TRIG.SET] Trig-
ger settings window
Move the flashing cursor to the [Trig Prio] item.
Select
Off Trigger events are ignored during [Pre-Trigger wait]
(default setting)
On
Trigger events are recognized (accepted) during [Pre-
Trigger wait].
50% of Recording Length
before trigger
Trigger Priority: [Off]
T
(After 50% of the Recording Length is recorded internally, the [Trigger
wait] state begins)
[Trigger wait][Pre-Trigger wait]
50% of Recording Length
after trigger
T
Trigger ignored
[Now Storing]
Start
Measurement
Recording Length before trigger
Trigger Priority: [On]
[Pre-Trigger wait]
50% of Recording Length after trigger
T
Trigger accepted
[Now Storing]
(A trigger event occurs while 50% of the Recording Length is being
recorded internally)
When a trigger event occurs during pre-trigger recording, the data actually recorded
may be shorter than the specified recording length. (In this case, the pre-trigger re-
cording length is shortened. The recording length after the trigger event is the speci-
fied recording length minus the specified pre-trigger period.)
Start
Measurement