R&S SMB100A, Operating Manual

Page: 186 / 528

Instrument Function
R&S
®
SMB100A
171 Operating Manual 1407.0806.32 ─ 21
Remote command:
:SENSe<ch>[:POWer]:ZERO
on page 324
Source
Selects the source for measurement.
"RF" Measurement source is the RF signal of the generator. The RF fre-
quency is used as the measurement frequency of the sensor and the
corresponding correction factor is used.
In this mode the RF frequency of the generator is send to the sensor
automatically if changed.
"User" Measurements source is any freely selectable source. The frequency
is entered manually under frequency (e.g. for measurement of ampli-
fier gain with 2 sensors).
Remote command:
:SENSe<ch>[:POWer]:SOURce
on page 323
Frequency
Source User only
Enters the frequency for measurement source "User".
Remote command:
:SENSe<ch>[:POWer]:FREQuency
on page 321
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
on page 322
:SENSe<ch>[:POWer]:OFFSet
on page 322
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.
RF Block