Configuring the RF Signal
R&S
®
SMW200A
586User Manual 1175.6632.02 ─ 30
"Add USBTMC Sensor"
Adds a detected R&S NRP sensor connected at the USB interface to
the list of sensors, including its device ID or name and its serial num-
ber.
Remote command:
:SLISt:SCAN:USENsor on page 893
8.9.4.3 NRP Power Viewer
The R&S SMW features the power viewer function for measuring or monitoring signals
with R&S NRP power sensors.
The R&S SMW can perform up to four power measurements simultaneously. The mea-
sured signals can be the RF output power or other selected signal sources.
About
The R&S SMW can perform up to four power measurements simultaneously.
Depending on the signal characteristic (CW, AM, pulsed, etc.) or the parameter to be
measured (average, peak, etc...) a suitable R&S power sensor must be used.
About the measuring principle, averaging filter, filter length, and achieving stable
results
A sensor measures the average or peak RF power of the source continuously. The
measurement results are displayed in the "NRP Power Viewer" dialog.
The power viewer function uses averaging filters for getting a stable readout.
Measurement results could be interfered for instance by to much noise in your setup,
by a bad supression of harmonics or non harmonics or when you reach the sensitivity
level of your power sensor.
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. This approach is referred as a two-step averaging process.
The factor of 2 in the formula arises because the output signals from the microwave
detector are chopped at the same rate as the time windows to suppress low-frequency
noise. An independent measured value can only be obtained from two consecutive val-
ues.
The variable N in the formula indicates the filter length. The filter length then directly
influences the measurement time. The filter length can be selected automatically or it
can be manually set to a fixed value.
Depending on the R&S NRP power sensor type, the manual setting of the filter length
varies in resolution:
●
Resolution = 1 for the R&S NRPxx power sensor family
●
Resolution = 2
n
for R&S NRP-Zxx power sensors, with n = 1 to 16
Follow the following general recommendation to find out the optimum filter length:
●
Always start a measurement in auto mode ("Filter > Auto").
Improving Level Performance
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