Tektronix OM4006D, Руководство пользователя

Страница: 77 / 205

Operating basics
Recording and playback You can record the workspace as a sequence of .mat fi les using
the Record button in the Of fl ine ribbon. These are recorded to
C:\Users\<user>\Documents\TekApplications\OUI\MAT Files.
You can play back the workspace from a sequence of .mat fi les by fi rst using
the Load button in the Of fl ine Commands section of the Home ribbon. Load a
sequence by marking the fi les you want to load using the Ctrl key and marking the
fi lenames with the mouse. You can also load a contiguous series using the Shift
key and marking the fi rst and last fi lenames in the series with the mouse.
Use the Run button in the Of fl ine Commands section of the Home ribbon to
cycle through the .mat fi les you recorded. OUI uses the fi lter settings stored in
the .mat fi les.
You can override the .mat fi le settings with certain Analysis Parameter settings by
using the Of fl ine controls near the bottom of the Analysis Parameters window.
This makes it possible to reprocess the saved data using different fi lters or other
settings, rather than those settings stored in the .mat fi le. (See page 37.)
Alerts
See the Appendix for alert messages information. (See page 109, Alerts .)
Managing data sets with
record length > 1,000,000
It is important to break up records larger than 1,000,000 points into blocks that can
fi t into the computer memory. This is done by setting the Blk Size to something
between 10,000 and 200,000. Typically 50,000 is a good balance between speed
of progress updates and overall processing time. When operating in this mode,
only the number of errors and other numerical measurements are maintained from
block to block. Time series information such as electric
fi eld values and raw data
are discarded to conserve memory. This means that if you do nothing else, the
large acquisition will end with only the
fi eld and symbol values for the last block
available along with the BER, EVM, and measurements which are collected over
the entire record. It is important in the large-acquisition case to learn how to save
intermediate data sets if the time-series data is needed.
Saving intermediate data sets: examples.
The simplest way to save intermediate
data is to record every record. (See page 52, PMD measurement .) However, this
may generate a very large set of fi les that will then need to be analyzed later. If
you only want to save the workspace on a particular event, you can use the save
command after the CoreProcessing call.
Once you have saved the data sets, you can view them later by using the Load
command described earlier. You can load them one at a time or as a group to see a
replay. Just be sure the correct analysis parameters are being used. If you save
the entire workspace by omitting the variable names in the save statement, then
you can also open the .mat
fi les later in MATLAB and use MATLAB plots to
examine the variables.
OM4000D Series Coherent Lightwave Signal Analyzer 53