Rohde & Schwarz SMBV100A, Руководство пользователя

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Instrument Function
R&S
®
SMBV100A
363 Operating Manual 1407.6062.32 ─ 08
Clipping
Switches baseband clipping on and off.
Clipping reduces the peak power of the resulting multi carrier signal according to the input
parameter "Target Crest Factor".
The resulting clipped peak power is defined by sum of the the RMS level of the unclipped
multi carrier signal and the input parameter "Target Crest Factor". Note that clipping
reduces also the RMS level. Hence the resulting crest factor of the clipped signal is slightly
above the "Target Crest Factor". In order to get the unclipped parts of the clipped multi-
carrier signal matched with the unclipped multicarrier signal, the RF output power should
be reduced by the difference between resulting crest factor and "Target Crest Factor".
SCPI command:
​
[:
​
SOURce<hw>]:
​
BB:
​
ARB:
​
MCARrier:
​
CLIPping[:
​
STATe]
​
on page 527
Target Crest Factor
Sets the value of the desired crest factor, if baseband clipping is enabled.
A "Target Crest Factor" above the crest factor of the unclipped multicarrier signal has no
effect.
SCPI command:
​
[:
​
SOURce<hw>]:
​
BB:
​
ARB:
​
MCARrier:
​
CLIPping:
​
CFACtor
​
on page 526
Filter Cut Off Frequency
Sets the cut off frequency of the final lowpass filter, if baseband clipping is enabled.
When the cut off frequency is set as half of the output sample rate, a final lowpass filter
improves the spectrum of the clipped multicarrier signal, but may also increase the result-
ing crest factor.
SCPI command:
​
[:
​
SOURce<hw>]:
​
BB:
​
ARB:
​
MCARrier:
​
CLIPping:
​
CUToff
​
on page 526
Signal Period Mode
Selects the mode for calculating the resulting signal period of the multi carrier waveform.
The carrier table provides an information button to obtain sample rate and file length data
of each carrier.
The resulting period is always calculated for all carriers in the carrier table irrespective of
their state (ON/OFF).
Note: Wrap-around and timing problems may occur when I/Q signals of different length
are used. Thus, demodulation of a carrier may be difficult or even impossible. It is there-
fore recommended to consider the timing already when creating the input I/Q files or to
adjust the signal duration to the carrier which is subsequently demodulated (in this case,
the other carriers are for interfering the signal only). These problems do not arise with
signals of the same standard (e.g. 3GPP).
The following modes are available:
"Longest File
Wins" The resulting signal period is defined by the longest I/Q file in the carrier
table. Shorter I/Q files are periodically repeated.
"Shortest File
Wins" The resulting signal period is defined by the shortest I/Q file in the carrier
table. Only the first part of longer I/Q files is used.
Baseband Signal - Baseband Block