Programming instructions

Downloading and Using Files
ARB Waveform Data Downloads
Chapter 4150
Data Requirements
IQ waveform data downloads have the following requirements:
• Data must be in signed, 2’s complement format.
• Data must be in 2-byte integers.
Two bytes are needed to express 16-bit waveforms. The signal generator accepts the most
significant byte (MSB) first.
• Input data must be between -32768 and 32767.
This range is based on the input specifications of the 16-bit DAC used to create the analog
voltages for the IQ modulator.
• Each IQ waveform must contain at least 60 samples to play in the waveform sequencer
(one sample equals one pair of IQ values and markers). An error message, “File format
invalid”, is displayed if this requirement is not met. The file format is discussed in
greater detail in the following sections.
• Each IQ waveform must contain an even number of samples to play in the waveform
sequencer. An error message, “File format invalid”, is displayed if this requirement is
not met. The file format is discussed in greater detail in the following sections.
• A marker file is always associated with an IQ waveform file. An empty (all zeros) default
marker file will be created if a marker file is not provided by the user.
• The user-defined marker file and IQ waveform data file must have the same name in the
signal generator.
File Structure and Memory
For volatile waveform memory (WFM1), there are approximately eight Msamples (32
Msamples with Option 002) of memory allocated in 1024-byte segments. For non-volatile
memory (NVWFM), Option 005 provides approximately 6 Gsamples of storage. Signal
generators without Option 005 provide 3 Msamples of NVWFM storage.
A waveform file must have a minimum of 60 samples of data. Each sample equals one IQ pair
of values, represented by four bytes of data, along with markers, represented by a single byte
of data. A 60 sample waveform file will occupy at 1024 bytes of waveform memory.
If a waveform file is too large to fit into a 1024-byte memory segment, additional memory
space is allocated in multiples of 1024 bytes. For example, a waveform represented by 500
samples is allocated to a 4096-byte memory segment (500 samples x 5 bytes).
Total memory usage may be much more than the sum of the samples that make up waveform
files. Many small waveform files can use large amounts of memory.