Dataman 520 Series - Manual (Page 23)

DATAMAN oscilloscope
User’s Guide
Each measuring channel of the DATAMAN 770 series oscilloscopes has its own AD
converter. No channel multiplexing is used for dual channel operation.
2.3.1. Digital Shielding (DSH)
Digital Shielding removes interference asynchronous with the measured signal, and it
does not affect frequency characteristics of the measured waveform. The only
negative effect of DSH is longer time period of waveform stabilization. It is, however,
very simple to turn the DSH off using the on-screen controls. The DSH efficiency
level corresponds to 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.
2.3.2. Trigger circuits
The block schematics of the dual level trigger circuits are shown on the figure 2.1.2.1.
AMP
AMP
DA
A
B
KB
KA
ta
tb
PTSS
STSS
E
A B E
A B E
DF
DF
EC
EC
trg
TDL
MS
Primary level
Secondary level
Fig. 2.3.2.1. – Block schematics of trigger circuits
Data for trigger circuits come either from Channel A, Channel B or from external
trigger input (E). The comparators KA an KB produce binary signals for Primary
Trigger Source Selector (PTSS) and Secondary Trigger Source Selector (STSS) while
the threshold of each comparator (ta, tb) can be set to any value in the vertical range.
If the actual output voltage of the channel is higher then the actual threshold the
output of comparator is set to 1 (TRUE). If it is lower than the threshold, the output
will be 0 (FALSE). The Trigger Source Selectors for each triggering level are
independent. It is possible to select the source of triggering signal for each level
independently. In addition to source selection, the PTSS and STSS can invert any of
the input signal The trigger event is generated with respect to change of the selector
(PTSS, STSS) output signal from 0 (FALSE) to 1 (TRUE). Constant level of the
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