![Rohde & Schwarz SMBV100A Operating Manual Download Page 455](http://html1.mh-extra.com/html/rohde-and-schwarz/smbv100a/smbv100a_operating-manual_1477735455.webp)
Instrument Function
R&S
®
SMBV100A
440
Operating Manual 1176.8016.02 ─ 17
Optimize Crest Factor Mode
Selects the mode for automatically minimizing the crest factor.
The carrier start phases are automatically set to this.
The crest factor represents the ratio of the peak voltage value to the rms voltage value.
The higher the crest factor and resulting dynamics of a signal, the greater the require-
ment for a power amplifier fed by the signal to be linear.
A very high crest factor arises when the carriers have an identical start phase, since
the carriers are periodically superposed and very high peak voltages occur in relation
to the rms voltage values.
Methods of reducing the crest factor differ with regard to both the optimization achieva-
ble and the time required for computation.
"Off"
There are no automatic settings for minimizing the crest factor. The
"Phase" setting has an effect.
"Chirp"
Very rapid crest factor optimization regardless of the number of carri-
ers. A minimal crest factor of < 3 dB is only obtained for multi carrier
signals in which all carriers are switched on and the power of the car-
riers is identical. In a configuration which differs from this, the achiev-
able crest factor is worse.
"Target Crest"
Optimization of the crest factor to a desired value for all carrier config-
urations. The optimization time depends on the number of carriers
and the desired crest factor. Computation time increases only when
the number of carriers exceeds 256 and the crest factor is below 4
dB. The desired value can be entered in "Desired Crest Factor".
Note:
Optimization can be cancelled at any time, and the current
value being displayed at that moment is then used.
Remote command:
[:SOURce<hw>]:BB:MCCW:CFACtor:MODE
Desired Crest Factor
Enters the desired crest factor.
This is only possible when the optimization "Target Crest" has been selected.
Remote command:
Table Setup Assistant
The "Table Setup Assistant" section can be used to set a selectable carrier range. The
carrier table can be edited in the "Carrier Table" dialog.
Carrier Start
Defines the start index of the carrier range to which the following settings are intended
to apply.
Remote command:
[:SOURce<hw>]:BB:MCCW:EDIT:CARRier:STARt
Baseband Signal - Baseband Block