R&S SMB100A Operating Manual page 187

®
R&S SMB100A
The filter length can be selected automatically or can be manually set to a fixed value.
As a preliminary, you should always check if the auto mode is giving satisfactory
results because you will always have to adjust an optimal, manual filter-length setting if
the power is not constant.
Selection "Fixed Noise" is offered for achieving defined measurement accuracy.
"Auto"
"User"
"Fixed Noise"
Remote command:
:SENSe<ch>[:POWer]:FILTer:TYPE
Filter Length ← Filter
Indicates the used filter length for filter type "Auto" or "User".
Remote command:
:SENSe<ch>[:POWer]:FILTer:LENGth:AUTO?
:SENSe<ch>[:POWer]:FILTer:LENGth[:USER]
Noise Content ← Filter
Sets the noise content for filter type "Fixed Noise".
Remote command:
:SENSe<ch>[:POWer]:FILTer:NSRatio
Timeout ← Filter
Sets a time limit for the averaging process.
Remote command:
:SENSe<ch>[:POWer]:FILTer:NSRatio:MTIMe
Operating Manual 1407.0806.32 ─ 21
The filter length is automatically selected and adapted to the currently
measured value. With very high signals the filter length and therefore
the measurement time can be short. With very low signal levels the
filter length and therefore the measurement time is increased in order
to reduce noise. The used filter length is indicated in the field to the
right, see Filter Length.
The filter length is set manually.
The filter length is entered in the entry window to the right. As the fil-
ter length works as a multiplier for the time window, this results in a
constant measurement time.
Note: The time window varies depending on the used sensor. For
most sensors it is fixed to 20 ms. For the R&S NRP-Z81 sensor it is
10 us. Therefore, the user filter length for the R&S NRP-Z81 has be
about 1000 times larger than the filter length for other sensors in
order to achieve the same filtering result.
The Auto Once button can be used to search for the optimum filter
length for the current measurement conditions. The found filter length
is indicated in the field to the right, see
The averaging factor is selected so that the sensors intrinsic noise (2
standard deviations) does not exceed the specified noise content.
The desired noise content is entered in the entry field to the right, see
Noise Content.
To avoid very long settling times when the power is low, the averag-
ing factor can be limited with the
Filter Length.
Timeout parameter.
on page 320
on page 318
on page 319
on page 319
on page 320
Instrument Function
RF Block
172