Instrument Function
R&S
®
SMU200A
300Operating Manual 1007.9845.32 ─ 15
"External Devi-
ces"
Set to On the parameters bandwidth, frequency offset and level offset
are indicated below.
SCPI command:
[:SOURce<hw>]:BB:IMPairment:OPTimization:UCORrection:EDEVices
on page 662
"Bandwidth"
Displays the bandwidth of the frequency response correction data in 10
MHz or 5 MHz intervals.
Note: Bandwidth is displayed if external devices are activated.
SCPI command:
[:SOURce<hw>]:BB:IMPairment:OPTimization:UCORrection:BWIDth
on page 662
"Frequency Off-
set"
Displays the frequency offset of the baseband frequency response cor-
rection data.
Note: Frequency offset is displayed if external devices are activated.
SCPI command:
[:SOURce<hw>]:BB:IMPairment:OPTimization:UCORrection:FREQuency:
OFFSet on page 665
"Level Offset"
Displays the level offset of the baseband frequency response correction
data.
Note: Level offset is displayed if external devices are activated.
SCPI command:
[:SOURce<hw>]:BB:IMPairment:OPTimization:UCORrection:LEVel:
OFFSet on page 666
5.7.2 AWGN - Noise Generator
The noise generator generates an AWGN signal (Additive White Gaussian Noise) in the
digital baseband, i.e. the noise power density has a Gaussian distribution and is distrib-
uted evenly across the frequency. This noise signal superimposes the (interference-free)
useful signal ("Additive Noise" mode). Typical applications for the noise generator are
bit-error or block-error measurements, depending on the set S/N or C/N ratio.
The Gaussian noise is generated by means of feedback shift registers with subsequent
probability transformation. The switching configuration is such that virtually ideal statis-
tical characteristics are achieved:
●
I and Q paths are decorrelated from each other.
●
The crest factor of 18 dB allows very small probabilities to be realized.
●
The period of the noise signal depends on the selected system bandwidth. The rela-
tionship of period P to system bandwidth B
sys
is approximated:
P ≈ 1*10
13
/ B
sys
This results in periods between 317 years with minimum bandwidth and approxi-
mately 2 days with maximum bandwidth.
This results in a period of approximately one month for 3GPP FDD with a bandwidth
of 3.84 Mcps, and a period of 427 days for GSM with 270.833 ksps.
Impairment of Digital I/Q Signal and Noise Generator - AWGN/IMP Block
To Next Page
Loading...
