Simulating Fading, Adding Noise and Predistortions, and Impairing the Signal
R&S
®
SMW200A
421User Manual 1175.6632.02 ─ 30
4, 7, 10 = Carrier Power = Status bar > Level = -30 dBm
5, 8 = Carrier+Noise Power = power at the RF A output; i.e. the power a connected power meter would
measure
6, 9 = Noise Bandwidth = System Bandwidth*Minimum Noise/System Bandwidth Ratio = 3.840 MHz*3 =
11.520 MHz
Use the built-in graphical signal monitoring function of the instrument to display the sig-
nal characteristics in real-time, see "To observe the effect of enabled additive noise
(AWGN)" on page 619.
Joint configuration of all streams
In Advanced mode, the instrument can generate the signal of one or more streams. In
the AWGN, with the parameter Coupled Mode you define how this streams are config-
ured; coupled, i.e. the same settings apply to all streams, or independently.
We recommend that you configure the AWGN settings in the default coupled mode.
When you disable the coupled mode, the instrument does not apply the current set-
tings to all streams. The settings of the individual streams are in the state they ware
before the coupled mode was enabled.
If you prefer to configure the streams independently, consider the interdependencies
listed in Table 6-1.
Table 6-1: State settings coupled and individual modes
AWGN > Coupled Mode > On AWGN > Coupled Mode > Off
Effect of the param-
eters
"AWGN > AWGN
Settings > General
> State" and
The states of all streams are coupled;
the parameters "AWGN > AWGN Set-
tings > General > State" and "AWGN >
State" have the same effect.
The parameter "AWGN > AWGN Settings
> General > (Stream) State" enables/disa-
bles each stream individually.
"AWGN > State" Hence, enabling/disabling the AWGN
block ("AWGN > On/Off") activates/
deactivates all streams.
The "AWGN > State > Off" deactivates all
streams.
The "AWGN > State > On" activates all
streams for that the "AWGN > AWGN Set-
tings > (Stream) State > On"
Application fields
Typically, the noise generator is required for the following tests:
●
In receiver sensibility tests with predefined SNR of the receiver, see "To configure
the AWGN for receiver sensibility tests with predefined SNR of the receiver"
on page 431
●
In bit-error or block-error measurements, depending on the set signal-to-noise ratio
(SNR)
●
Whenever a pure noise signal is required
Adding Noise to the Signal
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