R&S FSV3000 Series, User Manual

Page: 17 / 307

Basics on I/Q Data Acquisition and Processing
R&S
®
FSV/A3000 I/Q Analyzer
17 User Manual 1178.8536.02 ─ 01
4 Basics on I/Q Data Acquisition and Pro-
cessing
Some background knowledge on basic terms and principles used when describing I/Q
data acquisition on the R&S
FSV/A in general, and in the I/Q Analyzer application in
particular, is provided here for a better understanding of the required configuration set-
tings.
The I/Q Analyzer provides various possibilities to acquire the I/Q data to be analyzed:
●
Capturing analog I/Q data from the "RF Input" connector
●
Importing I/Q data from a file
Background information for all these scenarios and more is provided in the following
sections.
● Processing Analog I/Q Data from RF Input .............................................................17
● Using Probes ...........................................................................................................21
● Basics on External Generator Control .....................................................................24
● Basics on Input from I/Q Data Files ........................................................................ 35
● IF and Video Signal Output ..................................................................................... 36
● Receiving and Providing Trigger Signals ................................................................ 36
● I/Q Data Import and Export ..................................................................................... 37
● Basics on FFT .........................................................................................................38
4.1 Processing Analog I/Q Data from RF Input
Complex baseband data
In the telephone systems of the past, baseband data was transmitted unchanged as an
analog signal. In modern phone systems and in radio communication, however, the
baseband data is modulated on a carrier frequency, which is then transmitted. The
receiver must demodulate the data based on the carrier frequency. When using mod-
ern modulation methods (e.g. QPSK, QAM etc.), the baseband signal becomes com-
plex. Complex data (or:
I/Q data) consists of an imaginary (I) and a real (Q) compo-
nent.
Sweep vs sampling
The standard Spectrum application on the R&S FSV/A performs frequency sweeps on
the input signal and measurements in the frequency and time domain. Other applica-
tions on the R&S
FSV/A, such as the I/Q Analyzer, sample and process the individual I
and Q components of the complex signal.
Processing Analog I/Q Data from RF Input