Remote Control - Commands
R&S NRP-Z27/-Z37
1169.3870.12 6.10
E-2
SENSe:FUNCtion[?] <sensor_function>
In contrast to other sensors of the R&S NRP-Z series, the power sensor modules only implement the
Continuous Average
mode. Therefore, the command
SENSe:FUNCtion <sensor_function>
only accepts
the parameter
"POWer:AVG"
.
Table 6-3
Measurement mode "POWer:AVG"
<sensor_function>
Description of the measurement mode
"POWer:AVG"
Continuous Average
After occurrence of the trigger event, the mean power is measured in a time interval (sampling
window) whose width is defined with SENSe:POWer:AVG:APERture.
The single measurements are performed in pairs to obtain a more accurate measurement result by
differentiation. With the averaging function activated, this operation is repeated the number of times
specified by the averaging factor. With the averaging function activated, the actual measurement time
is thus
2
×
<SENSe:AVERage:COUNt>
×
<SENSe:POWer:AVG:APERture>
and with deactivated averaging function
2
×
<SENSe:POWer:AVG:APERture>.
Trigger events start one or several measurements in the Continuous Average mode (depending on the
TRIGger:COUNt parameter).
The query always yields
1
for
"POWer:AVG".
Default setting:
"POWer:AVG"
SENSe:POWer:AVG:APERture[?] 0.001 to 0.3
SENSe:POWer:AVG:APERture
defines the time interval (sampling window); measured values are
continuously recorded in this interval. In manual operation, the default setting of 20 ms in conjunction
with the activated smoothing (see
SENSe:POWer:AVG:SMOothing:STATe
) is sufficient in most cases.
Another value, which is normally higher, is required when the measurement result shows variations due
to modulation. Especially with low-frequency modulation, it is useful to adapt the size of the sampling
window exactly to the modulation period, which yields an optimum stable display.
Table 6-4
Optimum selection of the sampling window size (N = 1, 2, 3, …)
Smoothing
Optimum sampling window size
OFF
N
×
modulation period / 2
ON
N
×
modulation period
×
2
The theoretically shortest measurement time can then be obtained only with smoothing deactivated.
The situation is somewhat different when the sampling window cannot or should not be exactly adapted
to the modulation period. Smoothing should then be activated since even one measurement window
length of 5 periods is sufficient to reduce variations due to modulation to an acceptable extent;
variations are no longer perceptible with more than 9 periods. With smoothing deactivated, the situation
is significantly unfavourable. In this case, 5 instead of 300 periods are required and the variations
completely disappear as of 3000 periods.
The query yields the currently set width of the sampling window in seconds.
Default setting:
0.02 [s]
