R&S FSV3000 Series, User Manual

Page: 18 / 307

Basics on I/Q Data Acquisition and Processing
R&S
®
FSV/A3000 I/Q Analyzer
18 User Manual 1178.8536.02 ─ 01
I/Q Analyzer - processing complex data from RF input
The I/Q Analyzer is a standard application used to capture and analyze I/Q data on the
R&S
FSV/A. By default, it assumes the I/Q data is modulated on a carrier frequency
and input via the "RF Input" connector on the R&S FSV/A.
The A/D converter samples the IF signal at a rate of 200 MHz. The digital signal is
down-converted to the complex baseband, lowpass-filtered, and the sample rate is
reduced. The analog filter stages in the analyzer cause a frequency response which
adds to the modulation errors. An
equalizer filter before the resampler compensates
for this frequency response. The continuously adjustable sample rates are realized
using an optimal decimation filter and subsequent resampling on the set sample rate.
A dedicated memory ( capture buffer ) is available in the R&S FSV/A for a maximum of
400 Msamples (400*1000*1000) of complex samples (pairs of I and Q data). The num-
ber of complex samples to be captured can be defined (for restrictions refer to
Chap-
ter 4.1.1, "Sample Rate and Maximum Usable I/Q Bandwidth for RF Input" ,
on page 18).
The block diagram in Figure 4-1 shows the analyzer hardware from the IF section to
the processor.
Figure 4-1: Block diagram illustrating the R&S FSV/A signal processing for analog I/Q data (without
bandwidth extension options)
4.1.1 Sample Rate and Maximum Usable I/Q Bandwidth for RF Input
Definitions
●
Input sample rate (ISR) : the sample rate of the useful data provided by the device
connected to the input of the R&S FSV/A
●
(User, Output) Sample rate (SR) : the user-defined sample rate (e.g. in the "Data
Acquisition" dialog box in the "I/Q Analyzer" application) which is used as the basis
for analysis or output
●
Usable I/Q (Analysis) bandwidth : the bandwidth range in which the signal
remains undistorted in regard to amplitude characteristic and group delay; this
range can be used for accurate analysis by the R&S
FSV/A
Processing Analog I/Q Data from RF Input