Rohde & Schwarz SMBV100A, Руководство пользователя

Страница: 390 / 780

Instrument Function
R&S
®
SMBV100A
373 Operating Manual 1407.6062.32 ─ 08
When entering fewer carriers than the table contains, the approach is generally to delete
the superfluous entries from the table, and when entering more carriers than the table
contains the missing entries are usually added at the end of the table.
SCPI command:
​
[:
​
SOURce<hw>]:
​
BB:
​
MCCW:
​
CARRier:
​
COUNt
​
on page 591
Carrier Spacing
Sets the spacing between carriers for the Multi Carrier CW signal.
The carriers are arranged symmetrically around the HF carrier.
The total bandwidth is calculated as follow:
Total Bandwidth = ("Number of Carriers" - 1) * "Carrier Spacing"
The result must not exceed the system bandwidth of the instrument (see data sheet).
SCPI command:
​
[:
​
SOURce<hw>]:
​
BB:
​
MCCW:
​
CARRier:
​
SPACing
​
on page 593
Clock Frequency
Displays the clock rate at which the multi carrier signal is output by the arbitrary waveform
generator. The output clock rate depends on the number of carriers and the selected
carrier offset.
The value indicates the resolution during the marker generation.
SCPI command:
​
[:
​
SOURce<hw>]:
​
BB:
​
MCCW:
​
CLOCk
​
on page 595
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 requirement
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 achievable
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 carriers.
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 carriers is
identical. In a configuration which differs from this, the achievable crest
factor is worse.
Baseband Signal - Baseband Block