Programming instructions

Downloading and Using Files
ARB Waveform Data Downloads
Chapter 4 147
ARB Waveform Data Downloads
The signal generator accepts IQ waveform data downloads. After downloading the data file
into non-volatile memory, the file can be loaded into volatile memory and then played. These
user-defined IQ waveforms can also be sequenced together with other waveforms and played
as part of a waveform sequence.
NOTE The signal generator can use waveform files developed for the E443xB model
signal generators. Refer to “Downloading E443xB Signal Generator Files” on
page 161 for information on how to download these file types.
The IQ waveform data is used to drive the I and Q ports of the IQ modulator. The waveform
data is described using 16-bit I and 16-bit Q integer values in 2’s complement format. The I
and Q data values are interleaved, creating a single IQ waveform data file. The 2-byte I
integer and 2-byte Q integer values, along with a marker byte make up one sample and one
point is one pair of IQ values. There are five bytes of data for every sample as shown in Table
4-1 and Table 4-2.
The signal generator uses a marker file that is always associated with an IQ waveform file. If
you do not create a marker file for the IQ waveform file then the signal generator will
automatically create one. This automatically generated default marker file consists of all
zeros. The marker data drives the signal generator’s EVENT output connectors.
• Marker bit 1 drives EVENT 1 (Rear-panel BNC)
• Marker bit 2 drives EVENT 2 (Rear-panel BNC)
• Marker bit 3 drives EVENT 3 (Rear-panel Auxiliary D-Connector pin 19)
• Marker bit 4 drives EVENT 4 (Rear-panel Auxiliary D-Connector pin 18)
NOTE The default marker file is automatically created when no user defined marker
file is provided. The creation is done when the IQ waveform file is loaded into
volatile WFM1 (waveform memory) prior to playing. If the default marker file is
used, toggle the Mrk 2 to RF Blank softkey to off.
The marker file consists of 8-bit samples with each sample having four marker bits and four
unused bits. The result is that the IQ file will have four times as many bytes as the marker
file. See Table 4-1 and Table 4-2 for more detail on the file structure.
The signal generator uses this two-file format when generating waveform data. More details
are given in the following sections of this chapter.