Instrument Function
R&S
®
SMU200A
324Operating Manual 1007.9845.32 ─ 15
Example:
Fig. 5-25: 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<hw>]:BB:FOFFset on page 579
Phase Offset
Enters the phase offset for the baseband signal of the selected path compared to the
baseband signal of the other path.
For instruments equipped with an external baseband input ("BB Input"), this parameter
also enters the phase offset of the baseband signal of the selected path compared to the
external baseband input.
The phase offset affects the signal on the "Baseband block" output.
SCPI command:
[:SOURce<hw>]:BB:POFFset on page 580
Baseband Signal - Baseband Block
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