Rohde & Schwarz SMM100A, User Manual

Page: 266 / 1088

Adding noise and predistortions, and impairing the signal
R&S
®
SMM100A
266 User Manual 1179.1341.02 ─ 05
Figure 5-3: AWGN: Understanding the displayed information
1 = Bit Rate derived from the selected "Symbol Rate = 3.840 Msym/s"
2 = Selected Carrier/Noise Ratio
3 = Noise Power calculated from the "Carrier Power" and the "Carrier/Noise Ratio" = -30 dBm - 10 dB
= -40 dBm
4, 7, 10 = Carrier Power = Status bar > Level = -30 dBm
5, 8 = Noise Power = power at the RF 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 439.
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 274
●
In bit-error or block-error measurements, depending on the set signal-to-noise ratio
(SNR)
●
Whenever a pure noise signal is required
5.1.3 AWGN block
The "AWGN" block provides access to the settings for the AWGN generator , see
Chapter 5.1.4, "AWGN settings" , on page 267. The label in the AWGN block indicates
the AWGN mode that is activated. The quickest way to activate or deactivate the
AWGN generator is the "On/Off" switch in the AWGN block.
Adding noise to the signal