R&S WinIQSIM2 Software Manual - Rohde & Schwarz

R&S ® WinIQSIM2
Graphical User Interface
AWGN - Noise Generator
"ON/OFF
Period"
A regular marker signal that is defined by an ON/OFF ratio is generated.
A period lasts one ON and OFF cycle.
The "ON Time" and "OFF Time" are each expressed as a number of
samples and are set in an input field which opens when "ON/OFF
ratio" is selected.
Remote command:
​[:​SOURce]:​BB:​IMPort:​TRIGger:​OUTPut:​OFFTime​ on page 272
​[:​SOURce]:​BB:​IMPort:​TRIGger:​OUTPut:​ONTime​ on page 272
Remote command:
​[:​SOURce]:​BB:​IMPort:​TRIGger:​OUTPut:​MODE​ on page 272
5.11 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 distributed
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 statistical
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.
Apart from the "Additive Noise" mode, there are also the "Noise Only" and the "CW Interferer"
mode. In the "Noise Only" mode a pure noise signal is generated and modulated
to the carrier. In the "CW Interferer mode", a sinusoidal signal with an adjustable frequency
offset to the baseband signal is generated and added to the baseband signal by
means of a counter instead of a shift register.
The achievable noise bandwidth can not exceed the sampling rate of the baseband. This
rate is assumed to be 50 MHz in case of Noise Only where 100.000 samples are generated.
5.11.1 AWGN Settings Dialog
The "AWGN Settings" menu is divided into the following sections.
The RFI signal generator is activated, the mode selected and the interfering signal is
configured in the top section of the menu.
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