Rohde & Schwarz ZNL Series, Руководство пользователя

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Basics on I/Q Data Acquisition and Processing
R&S
®
ZNL
24 User Manual 1178.5989.02 ─ 06
The RBW is determined by the following equation:
Length Window
Rate Sample
Bandwidth Normalized RBW
 
Equation 4-1: Definition of RBW
(Note: The normalized bandwidth is a fixed value that takes the noise bandwidth of the
window function into consideration.)
The maximum RBW is restricted by the Analysis Bandwidth , or by the following equa-
tion, whichever is higher:
3
Rate Sample * Bandwidth Normalized
RBW
max

If a higher spectral resolution is required, the number of samples must be increased by
using a higher sample rate or longer record length.
The minimum achievable RBW depends on the sample rate and record length, accord-
ing to the following equation:
 
Length cord Re , 4096 min
Rate Sample Bandwidth* Normalized
RBW
min

To simplify operation, some parameters are coupled and automatically calculated, such
as record length and RBW.
RBW mode
Depending on the selected RBW mode, the resolution bandwidth is either determined
automatically or can be defined manually.
Auto mode :
This is the default mode in the I/Q Analyzer. The RBW is determined automatically
depending on the
Sample Rate and Window Length , where the window length corre-
sponds to the Record Length , or a maximum of 4096.
If the record length is larger than the window length, multiple windows are combined;
the FFT length is 4096.
A Flatop window function is used.
Manual mode :
The RBW is user-definable.
The Window Length is adapted to comply with Equation 4-1 . Since only window
lengths with integer values can be employed, the Sample Rate is adapted, if neces-
sary, to obtain an integer window length value.
If the record length is larger than the window length, multiple windows are combined;
the FFT length is 4096.
A Flatop window function is used.
Basics on FFT