Basics on I/Q Data Acquisition and Processing
R&S
®
FSWP
21User Manual 1177.5856.02 ─ 07
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 FSWP
●
(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 FSWP
●
Record length: Number of I/Q samples to capture during the specified measure-
ment time; calculated as the measurement time multiplied by the sample rate
For the I/Q data acquisition, digital decimation filters are used internally in the
R&S FSWP. The passband of these digital filters determines the maximum usable I/Q
bandwidth. In consequence, signals within the usable I/Q bandwidth (passband)
remain unchanged, while signals outside the usable I/Q bandwidth (passband) are
suppressed. Usually, the suppressed signals are noise, artifacts, and the second IF
side band. If frequencies of interest to you are also suppressed, try to increase the out-
put sample rate, which increases the maximum usable I/Q bandwidth.
Bandwidth extension options
You can extend the maximum usable I/Q bandwidth provided by the R&S FSWP in the
basic installation by adding options. The maximum bandwidth provided by the individ-
ual option is indicated by its number, for example, B40 extends the bandwidth to
40 MHz.
As a rule, the usable I/Q bandwidth is proportional to the output sample rate. Yet, when
the I/Q bandwidth reaches the bandwidth of the analog IF filter (at very high output
sample rates), the curve breaks.
● Bandwidth Extension Options................................................................................. 21
● Relationship Between Sample Rate, Record Length and Usable I/Q Bandwidth... 22
● R&S FSWP Without Additional Bandwidth Extension Options............................... 23
● R&S FSWP with I/Q Bandwidth Extension Option B80...........................................23
● R&S FSWP with Activated I/Q Bandwidth Extension Option B320.........................24
4.1.1.1 Bandwidth Extension Options
Max. usable I/Q BW Required B-option
80 MHz B80
320 MHz B320
Processing Analog I/Q Data from RF Input
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