Adding noise and predistortions, and impairing the signal
R&S
®
SMM100A
265
User Manual 1179.1341.02 ─ 05
Where the bit rate value is retrieved from?
The parameter "AWGN > Noise Power / Output Results > Bit Rate" indicates the value
used by the C/N or E
b
/N
0
calculation. The value is retrieved automatically depending
on the configured baseband signal:
●
For signals generated by the "Custom Digital Mod", the bit rate is determined by
the selected standard
(see parameter "Custom Dig Mod > General" > "
Mod > Modulation Type").
●
For signals generated in accordance to a digital standard, the bit rate is often a
standalone parameter.
Some test cases however, for example the 3GPP base station tests (TS
25.141),
specify the E/N settings that apply to channel-coded data or block segments. Set
the parameter "Bit Rate" to the required value, e.g. the bit rate before or after chan-
nel coding.
Understanding the displayed information
The following example explains the impact of the AWGN settings on the signal and
noise parameters.
See
for an example of an AWGN generation with the following configuration:
●
"Baseband"
–
"Custom Digital Modulation > Set acc. to standard > WCDMA-3GPP"
–
"State > On".
–
"Symbol Rate = 3.840
Msym/s"
●
"AWGN"
–
"General > Mode > Additive Noise"
–
"General > Min Noise/System Bandwidth Ratio = 3"
–
"General > State > On"
–
"Noise Power / Output Results > Show Results for Output > RF"
–
"Noise Power / Output Results > Reference Mode > Carrier"
–
"Noise Power / Output Results > Carrier/Noise Ratio = 10
dB"
●
"RF > On"
Adding noise to the signal
