Manual

WM-RCM-E Rev D ISSUED: February 2005 51
C HAPTER F OUR Understanding and Managing Waveforms
Know Your Waveform
A waveform can be said to have two main parts. One is its basic data array: raw data values from the
oscilloscope’s ADCs (Analog-to-Digital Converters) obtained in the waveform’s capture. The other is the
description that accompanies this raw data: the vertical and horizontal scale or time of day, for example,
necessary for a full understanding of the information contained in the waveform. When these parts are
transmitted together, the descriptor comes first.
You can access this descriptive information by remote control using the INSPECT? query, which interprets it
in an easily understood ASCII text form. And you can rapidly transfer the waveform data using the
WAVEFORM? query. You can write it back into the oscilloscope with the WAVEFORM command.
Your instrument contains a data structure (template, see Appendix II) that provides a detailed description of
how waveform information is organized. Although a sample template is provided with this manual, we suggest
you use the TEMPLATE? query to access the instrument template in the oscilloscope itself (the template may
change as your oscilloscope’s firmware is enhanced).
Using the STORE and STORE_SETUP commands, you can also store waveforms in preformatted ASCII
output for popular spreadsheet and math processing packages.
LOGICAL DATA BLOCKS
Each of your waveforms will normally contain at least a waveform descriptor and data array block. However,
other blocks may also be present in more complex waveforms.
Waveform Descriptor block (WAVEDESC): This includes all the information necessary to reconstitute the
display of the waveform from the data, including: hardware settings at the time of acquisition, the exact time
of the event, kinds of processing performed, your oscilloscope name and serial number, the encoding format
used for the data blocks, and miscellaneous constants.
Sequence Acquisition Times block (TRIGTIME): This is needed for sequence mode acquisitions to
record the exact timing information for each segment. It contains the time of each trigger relative to the trigger
of the first segment, as well as the time of the first data point of each segment relative to its trigger.
Random Interleaved Sampling times block (RISTIME): This is required for RIS acquisitions to record the
exact timing information for each segment.
First Data Array block (SIMPLE or DATA_ARRAY_1): This is the basic integer data of the waveform. It
can be raw or corrected ADC data or the integer result of waveform processing.