Dataman 520 Series - Manual (Page 18)

DATAMAN oscilloscope
User’s Guide
Acquiring data before and after trigger with selectable trigger position displays the
waveform before and/or after the trigger. The position of the trigger is selectable by
the user. In this mode the hardware of the oscilloscope starts data acquisition
immediately after the start of measurement. The trigger event terminates the data
acquisition after collecting the data amount set by the user. The ammount of data
acquired after the trigger can be set from two to over 63000 samples. This is much
more than the capacity of the onboard data buffer. This feature allows you to display
the waveform corresponding with the capacity of the onboard storage (4KS or 8KS
for each channel depending on the model) before the trigger or waveforms after the
trigger delayed from the occurrence of the trigger up to 63000 samples in length of the
capacity of the onboard storage. The trigger position can be set to any place between
these margins. The “Hold Off” timer allows the user to prevent the occurrence of a
trigger event after the start of data acquisition. This feature allows you to acquire the
proper amount of data before the trigger.
Each measuring channel of the DATAMAN 520 series oscilloscopes has its own AD
converter. No channel multiplexing is used for dual channel operation.
2.2.1. Digital Shielding (DSH)
Digital Shielding removes interference asynchronous with the measured signal, it does
not affect the frequency characteristics of the measured waveform. The only negative
effect of DSH is longer time period for waveform stabilization. It is, however, very
simple to turn the DSH off using the on-screen controls. The DSH efficiency level
corresponds to the DSH level factor that can be set to any value from 2 to 64. The
higher the level you choose, the longer it takes to stabilize.
2.2.2. Trigger circuits
The block schematics of the dual level trigger circuits are shown in the figure 2.2.2.1.
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