Configuring the RF signal
R&S
®
SMM100A
331
User Manual 1179.1341.02 ─ 05
It is possible to set f
STARt
> f
STOP
and f
STARt
< f
STOP
, so that even a negative value is per-
mitted for the "Span".
If you change the start and/or stop frequency, the span and center frequency change
accordingly, and vice versa.
Sweep steps
In the following, you see how the sweep steps are calculated depending on the defined
spacing mode. The formulas show a frequency sweep, but apply to the level settings in
the same way.
The step size is added to the current value, to get the subsequent sweep step.
With
linear
scaling, the next frequency is calculated according to:
f
2
= f
1
+ step_lin
In the
logarithmic
scaling, the step size is determined in per cent, as a constant frac-
tion of the current frequency.
Successive frequencies are calculated as follows:
●
For f
STARt
< f
STOP
f
2
= f
1
*(1 + step_log/100)
If f
2
> f
STOP
, then f
2
= f
STOP
●
For f
STARt
> f
STOP
f
2
= f
1
/(1 + step_log/100)
If f
2
< f
STOP
, then f
2
= f
STOP
With "Shape = Triangle", the frequency values on the slope from f
STOP
to f
STARt
are the
same as on the slope from f
STARt
to f
STOP
.
If you specify the number of steps within the sweep range, the step size is adjusted
according to the following correlation:
●
For
linear
sweeps and f
STARt
< f
STOP
POINts
frequency
= ((f
STARt
- f
STOP
)/step_lin) +1 = (f
SPAN
/step_lin) + 1
●
For
logarithmic
sweeps and f
STARt
< f
STOP
POINts
frequency
= ((log f
STOP
- log f
STARt
)/log step_log) +1
If step_log changes, the value of POINts is adjusted. The f
STARt
and f
STOP
values are
retained.
7.10.2.2
Sweep signal shapes
The R&S
SMM100A supports the following sweep shapes:
●
Sawtooth
The sweep sequence resembles a sawtooth. One sweep runs from start to stop
frequency, or level value respectively. Each subsequent sweep starts again at the
start value.
Varying the RF signal in list or sweep mode
