
VT DSO-2A20 Manual Rev. 1.1
Virtins Technology
number of taps used in the moving average, as the adjacent samples are
correlated after moving average.
Non-uniform behavior at the starting and/or the ending parts of the data frame
due to the fact that it is not possible to apply exactly the same moving average
filter there as the one applied to the middle part of the data frame.
No Yes
To use software DSP based bit resolution enhancement, right click anywhere within the
oscilloscope window and choose [Oscilloscope Processing]>“Digital Filtering”>
“Arbitrary”> “IIR Coefficients”. Then select an appropriate moving average filter file from
the IIR subdirectory. Software DSP based bit resolution enhancement is generally not
recommended when hardware DSP based bit resolution enhancement is available.
1.8.2 Oscilloscope Normal Frame Mode, Record Mode and Roll Mode
The second-generation VT DSOs support both normal frame and streaming modes. There are
two streaming modes: Record Mode and Roll Mode. The following is a comparison table of
these three modes.
Normal Frame Mode
Record Mode
Roll Mode
Max. Sampling
Frequency
High Medium Low
Record Length
Low
(limited by DSO
hardware buffer size)
High
(limited by hard disk
space)
Medium
(limited by computer
memory size)
Trigger
Trigger per frame
Trigger required at
startup (first frame) only
Trigger required at
startup (first segment)
only
Discontinuity within each
data frame
Absolutely no
Normally no
Normally no
Discontinuity between
adjacent data frames
Most likely
Normally no
Normally no
Usage General
purpose
Used
when
Record
Length exceeds the limit
determined by the DSO
hardware buffer
Generally used to provide
instant display response
at very slow sweep speed.
Without it, the entire
frame of data must be
acquired first before the
display can be updated.
Also used when Record
Length exceeds the limit
determined by the DSO
hardware buffer
1.8.2.1 Normal Frame Mode
Normal frame mode is the most commonly used oscilloscope mode. Each data frame is
triggered and acquired individually. There may be discontinuity between two adjacent data
frames. The length of the data frame is limited by the DSO hardware buffer size. One major
advantage of this mode is that it supports the highest sampling frequency of the ADC device.
1.8.2.2 Record Mode
Record Mode can be activated using either of the following methods:
•
Clicking the Record button in the Sampling Parameter Toolbar
www.virtins.com 17 Copyright © 2017 Virtins Technology