R&S FSPN, User Manual

Page: 108 / 555

Common Measurement Settings
R&S
®
FSPN
108 User Manual 1179.4363.02 ─ 01
Capture Range
The "Capture Range" defines the bandwidth with which the R&S FSPN searches for a
signal or tracks drifting signals.
Use a "Normal" capture range for stable or slowly drifting DUTs. For fast drifting DUTs,
use a "Wide" capture range.
Use a "40 MHz" capture range to measure carriers swept from -40 MHz to +40 MHz
relative to the center frequency. Additional spurs and restrictions of the measurement
accuracy are possible for CW signals, or carriers swept in other frequency ranges. For
specifics of the measurement accuracy, refer to the data sheet.
The capture range is available for the phase noise measurement.
Remote command:
[SENSe:]SWEep:CAPTure:RANGe
on page 360
Defining the measurement range
Noise measurements determine the noise of a DUT over a certain measurement
range. The measurement range is defined by the two offset frequencies that you define
("Start Offset" and "Stop Offset").
The frequency offsets themselves are relative to the carrier frequency of the DUT: a
frequency offset of 1
MHz, for example, measures the noise characteristics up to a dis-
tance of 1 MHz from the carrier. The maximum offset that you can define depends on
the hardware you are using.
For baseband noise measurements, the frequency range is defined by absolute start
and stop frequencies instead of relative offset frequencies. The center frequency repre-
sents the carrier frequency. The measurement range or span depends on the input you
are using: For the RF input, it depends on the hardware you are using. For the base-
band input, measurements up to 40
MHz are supported.
The measurement range thus defines the scale of the x-axis in the "Phase Noise" dia-
gram.
The measurement range again is divided into several (logarithmic) decades, or, for
configuration purposes, into
half decades .
Note: For frequency stability measurements , the start and stop frequency offsets of the
phase noise measurement are the reciprocal values of the start and stop values of the
observation time ("Tau Start" and "Tau Stop").
Tau Start and Tau Stop thus define the scale of the x-axis in the "Allan Variance" and
"Allan Deviation" diagrams.
Remote command:
Start offset:
[SENSe:]FREQuency:STARt
on page 359
Stop offset:
[SENSe:]FREQuency:STOP
on page 359
Start Tau:
[SENSe:]TIME:STARt
on page 367
Stop Tau:
[SENSe:]TIME:STOP
on page 367
Measuring low frequency and low level signals
The R&S FSPN provides functionality to measure the phase noise of signals with a low
frequency and / or a low signal level.
●
Low frequencies can be measured by applying the low pass filter.
●
Low signal levels can be measured by selecting the appropriate level setting.
Frequency