R&S SMJ100A, Руководство по эксплуатации

Страница: 384 / 874

Instrument Function
R&S
®
SMJ100A
368 Operating Manual 1403.7458.32 ─ 14
A waveform is a file with specified file format containing raw IQ samples. The IQ values
are calculated in advance and stored as waveform files with predefined extension
*.wv
. When created by the R&S SMJ, the instrument inserts a tagged waveform
header at the beginning of each created ARB file. For more information, refer to Chap-
ter 7.4, "Waveform and List Format" , on page 490.
Depending on whether the R&S SMJ creates the waveform files itself or not, two wave-
form files sources can be distinguished:
●
Internally generated waveforms
The ARB generator enables the calculation and the generation of multi segment
and multi carrier waveform files as well as the build in function to create a test
waveform (e.g. a sine or rectangle signal) and keep it as a file or in the RAM.
Several digital standards provide the special function "Generate Waveform File"
and enable the calculation and storage of the signal as a waveform file that can be
afterwards processed by the ARB generator.
●
Externally generated waveforms
The ARB can also process externally generated waveform files e.g. the waveform
files generated on a PC by the Windows software package R&S
WinIQSIM2, the
software R&S ARB Toolbox, the R&S SMx-K6 Pulse Sequencer software or sig-
nals calculated using a mathematical program such as Matlab.
For more information also on the required options, refer to the Rohde&Schwarz
web site at
http://www.rohde-schwarz.com . See also the Application Note 1MA28,
“IQWizard - I/Q Signal Measurement and Conversion".
The externally generated waveform files can be loaded into the instrument via one
of the available interfaces (USB, LAN or GPIB). Usually, the waveform file is stored
on one of the network drives which are accessible for the operating system.
Playing and Streaming Waveform Files
Depending on the way the loaded waveforms are processed, an ARB works in one of
the following modes:
●
Playback from the internal memory
In the most common case, the ARB generator plays back a waveform file with a
selectable clock frequency. The R&S
SMJ loads the entire file into the ARB mem-
ory from where the IQ samples are played repeatedly.
This is suitable for files of limited size, e.g. up to 256 MB for instruments equipped
with option R&S
SMJ-B10.
The maximum size for streaming and ARB files is also listed in the R&S SMJ data
sheet.
●
Streaming
For playing of larger waveform files, the R&S
SMJ provides the second ARB mode,
the HDD streaming mode. In this mode, the instrument streams the modulation
data direct form its hard drive (HDD). HDD streaming is recommended for process-
ing of files that require more ARB memory than the currently installed one. The
HDD streaming limits the sample rate to 1 MHz.
Baseband Signal - Baseband Block