R&S SMJ100A, Руководство по эксплуатации

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Instrument Function
R&S
®
SMJ100A
415 Operating Manual 1403.7458.32 ─ 14
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 unclip-
ped multi carrier signal and the input parameter "Target Crest Factor". Note that clip-
ping 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 multicarrier 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".
Remote command:
[:SOURce<hw>]:BB:ARBitrary:MCARrier:CLIPping[:STATe]
on page 603
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.
Remote command:
[:SOURce<hw>]:BB:ARBitrary:MCARrier:CLIPping:CFACtor
on page 602
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
resulting crest factor.
Remote command:
[:SOURce<hw>]:BB:ARBitrary:MCARrier:CLIPping:CUToff
on page 602
Signal Period Mode
Selects the mode for calculating the resulting signal period of the multi carrier wave-
form. 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
therefore 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 car-
rier table. Shorter I/Q files are periodically repeated.
Baseband Signal - Baseband Block