Instrument Function
R&S
®
SMU200A
445Operating Manual 1007.9845.32 ─ 15
Example:
The following graph shows the setting range for the frequency offset.
Fig. 5-35: 3GPP FDD signal (chip rate 3.84 Mcps, root-cosine filter 0.22).
The complex useful bandwidth of a signal which has been filtered using a root-cosine
filter with roll off alpha is calculated as follows:
f
use
= (1+ alpha) * f
symbol
f
symbol
= the symbol rate or chip rate of the signal.
In the example the complex useful bandwidth is calculated as follows:
f
use
= (1+ 0.22) * 3.84 MHz = 4.6848 MHz.
So as to comply with the condition requiring a maximum I/Q bandwidth of 40 MHz, the
valid range of values for the frequency offset is then:
-40MHz + 4.6848MHz/2 <= f
offset
<= 40MHz - 4.6848MHz/2 or
-35.3152MHz <= f
offset
<= 35.3152MHz
In the case of ARB signals, the output clock rate can be used for estimating the maximum
I/Q bandwidth of the waveform.
SCPI command:
[:SOURce]:BBIN:FOFFset on page 692
Path Gain
Enters the relative gain for the external baseband signal compared with the signals of the
other baseband sources. The gain affects the signal on the output of the "BB Input" block.
Note: In case the baseband signal is additionally faded and routed at the output of the
fading simulator, so that the faded signals from both paths are summed, the real path
gain is measured at the output of the "Fading" block and set with the fading parameter
"Summation Ratio A/B" (see description “Fading Simulator”, section “Summation Ratio
A/B”).
The relative gain set with the parameter "Path Gain" in the "Baseband" block is ignored.
External Baseband Signal - Baseband Input
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