VT DSO-2A20 Manual Rev. 1.1
Virtins Technology
Hardware based offset and gain adjustment is superior to software based methods in that it
does not reduce the precious dynamic range offered by the ADC devices.
1.8.11 Upgradable software, firmware, and hardware based DSP algorithm
The computer software as well as its license level, the firmware in the DSO, and the
hardware based DSP algorithm in the DSO are all remotely upgradable. What you need to
do is to check our website frequently to see if there is a free upgrade available for download.
1.9 Non-routine Applications
The non-routine applications refer to those applications that are not considered as routine
tasks of an ordinary oscilloscope. With VT DSO’s capability of simultaneous input and
output, you can generate a stimulus to a Device Under Test (DUT) and acquire the response
from it at the same time. Different stimuli can be generated and the responses can be
analyzed in different ways. The characteristics of the DUT, such as frequency response and
distortion, can then be obtained. You can even configure and then perform a sequence of
automated test steps to evaluate a DUT using the Device Test Plan software module.
The following sections provide information and guidelines to help you to configure your own
measurement settings for your specific applications.
1.9.1 Frequency Response Measurement
Frequency response includes magnitude frequency response and phase frequency response.
Most of the time you may be only interested in the magnitude frequency response. However,
if you need to measure both, i.e. Bode Plot (also called Gain & Phase Plot, or Transfer
Function), then Multi-Instrument Pro is required. For Bode plot measurement, the stimulus
should be fed to the DUT as well as Channel B while the response from the DUT should be
fed to Channel A.
There are quite a few methods to measure the frequency response of a DUT.
(1)
Stimulus with an equal amount of energy per Hz of bandwidth in the frequency range of
interest together with FFT spectrum analysis
The stimulus can be a white noise or MLS (Maximum Length Sequence) signal. No
synchronization between the signal generator and oscilloscope is required. Just start the
signal generator first and then start the oscilloscope. Inter-frame averaging should be
used to get better results. You can set the number of frames to be averaged by right
clicking anywhere within the spectrum analyzer window, selecting [Spectrum Analyzer
Processing]> “Inter-Frame Processing”> “Linear Average” and choosing a number in the
“Frames” field. Rectangle Window should be used in the spectrum analyzer. FFT size of
the spectrum analyzer should be equal to or greater than the Record Length of the
oscilloscope. If MLS is used, its length should be greater than the FFT size. Stop the
oscilloscope first before stopping the signal generator.
A linear frequency swept sine signal can also be used as the stimulus. Trigger level
should be set properly such that the oscilloscope only gets triggered right after the
frequency sweep starts. Start the oscilloscope first and then start the signal generator. If
www.virtins.com 23 Copyright © 2017 Virtins Technology
