Instrument Function
R&S
®
SMBV100A
246
Operating Manual 1176.8016.02 ─ 17
Remote command:
Frequency
Source User only
Enters the frequency for measurement source "User".
Remote command:
Level Offset
Activates and defines a level offset which is added to the measured value. This allows
e.g. an attenuator in the signal path to be considered. The offset is always entered in
dB, irrespective of the selected unit for result display.
Remote command:
:SENSe<ch>[:POWer]:OFFSet:STATe
Filter
Determines the length of the filter used for the measurement. The filter length affects
the measurement time directly.
The averaging filter is used to reduce fluctuations in the measured result to the extent
desired. Such fluctuations can be caused by inherent noise of the measuring instru-
ment, modulation of the measurement signal or beats from the superposition of adja-
cent carriers. A more stable display has to be traded off against longer measurements.
The measurement result is obtained from a two-stage averaging process.
Note:
Longer measurements do not mean that it takes longer to display a new result,
but rather that it takes longer for the result to settle when the power changes.
Measurements are continuously repeated in a predefined time window. The measure-
ment result is obtained by averaging the measured values for the last 2N time win-
dows. The number N is the filter length, the factor of 2 arises because the output sig-
nals from the microwave detector to suppress low-frequency noise are chopped at the
same rate as the time windows, which means that an independent measured value can
only be obtained from two consecutive values. As the filter length is the multiplier for
the time window it directly influences the measurement time.
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"
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
.
RF Block
