R&S 1322.8003K06, Руководство пользователя

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Common Measurement Settings
R&S
®
FSPN
101 User Manual 1179.4363.02 ─ 01
The baseband input is always DC coupled, which allows you to measure the noise
characteristics of a DUT near 0
Hz (DC) in the context of baseband noise measure-
ments.
Note that you have to turn on the baseband input deliberately before you can use it.
When the baseband input is active, the RF input is automatically turned off.
A typical test setup for measurements over the RF input depends on the selected mea-
surement and the equipment used in the test setup. A schematic representation of
such a setup is provided in the dialog box.
See Chapter 3.4.2.3, "Baseband Noise Measurement" , on page 69 for more informa-
tion on how to set up and perform baseband noise measurements.
6.3 Level Characteristics
Measurement results usually consist of the measured signal levels (amplitudes) dis-
played on the vertical y-axis for the determined frequency spectrum (horizontal, x-axis).
The settings for the vertical axis, regarding amplitude and scaling, are described here.
● Signal Attenuation .................................................................................................101
● Amplitude Characteristics ..................................................................................... 102
● Diagram Scale .......................................................................................................104
6.3.1 Signal Attenuation
Signal attenuation reduces the level of the signal that you feed into the R&S FSPN.
Reducing the level is necessary to protect the input mixer from signals with high levels,
because high levels can cause an overload of the input mixer. An input mixer overload
in turn can lead to incorrect measurement results or even damage or destroy the input
mixer.
The level at the input mixer is determined by the set RF attenuation according to the
formula:
level
mixer
= level
input
- RF attenuation
The maximum level that the input mixer can handle is 0 dBm. Levels above this value
cause an overload. The R&S FSPN indicates an overload situation by the "RF OVLD"
label in the status bar.
The R&S FSPN features a mechanical attenuator. The mechanical attenuator is loca-
ted directly after the RF input of the R&S FSPN. Its step size is 5 dB.
Level Characteristics