User Manual LW120
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 LW120 is using 14-bit DAC’s to generate arbitrary
waveforms. Converting 14 bits to precision shows that each data
point can be placed along the vertical axis with a precision of
1/16,384.
Memory Depth
– Defines how many data points can be stored for
a single waveform cycle. The LW120 has the following waveform
memory capacity:
1 Meg – standard memory configuration
4 Meg – optional memory expansion
Having large memory capacity has big advantages. 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
LW120 lets you divide the memory bank to smaller segments and
load different waveforms into each segment.
Using the Arbitrary
Waveforms
Downloading waveforms to the LW120 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 3-32 and use the following description to learn how
to output arbitrary waveforms. Here is what you do:
1. Press the WAVEFORM button
2. Select and press the ARB option
3. Select and press the Segment CH1 button
4. Rotate the dial to select the required memory segment
If you did not make programming errors and did not make any
mistake while downloading your waveform segments, then the
output should generate your desired waveform. This is not all, you
now have to make sure that the sample clock is programmed to the
correct rate so that your output will match your frequency
requirements. This is easy since we already showed you earlier
how to set sample clock frequency and how to compute the output
frequency from the sample clock value and the number of points
you are using for your waveform.
Using The Instrument 3-47
