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2074
User Manual
What Are Arbitrary
Waveforms?
Generating
Arbitrary
Waveforms
3-36
Arbitrary waveforms are generated from digital data points, which
are stored in a working memory. The working memory is connected
to a digital to analog converter (DAC) and a sample clock generator
is clocking the data points, one at a time, to the output circuit. In
slow motion, the output generates a waveform that resembles the
look of a staircase. In reality, the DAC is generating amplitude hops
that depend on bit arrangement and sample clock speed.
The working memory has two major properties: vertical resolution
and memory depth.
Vertical Resolution – This term defines the precision along the
vertical axis of which data points can be placed and generated by
the DAC. The 2074 is using 16-bit DAC's to generate arbitrary
waveforms. Converting 16 bits to precision shows that each data
point can be placed along the vertical axis with a precision of
1/65,536.
Memory Depth – Defines how many data points can be stored for a
single waveform cycle. The 2074 has 1 M waveform memory
capacity and 2 M waveform memory as an option.
Having such large memory capacity is an advantage. Modern
applications in the telecommunications industry require simulation
of long waveforms without repeatable segments. The only way to
create such waveforms is having sufficient memory depth. On the
other hand, if you do not need to use very long waveforms but must
have many other waveforms stored in your working memory, the
2074 lets you divide the memory bank to smaller segments and
load different waveforms into each segment.
Downloading waveforms to the 2074 and managing arbitrary
memory are explained in the programming section of this manual.
This section assumes that you have already downloaded
waveforms and want the instrument to output these waveforms.
Refer to Figure 3-16 and use the following description to learn how
to output arbitrary waveforms and how to program arbitrary
waveform parameters. To select Arbitrary waveforms as the output
waveform type press Waveforms, then Arbitrary. The screen as
shown in Figure 3-16 will display and the output will already
generate arbitrary waveforms. Note the channel you are currently
program and make sure the icon at the upper right corner agrees
with your required programming sequence. Use the following
procedure to modify the parameters that are associated with the
arbitrary waveform function:
1. Press the soft key next to the required parameter to display the
edit field
2. Punch in the value using the numeric keypad. Be careful not to
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