Remote control commands
R&S
®
NRP18S-xx
62
User Manual 1178.3686.02 ─ 07
Configuring continuous average measurements of modulated signals
When measuring modulated signals in continuous average mode, the measurement
can show fluctuation due to the modulation. If that is the case, adapt the size of the
sampling window exactly to the modulation period to get an optimally stable display. If
the modulation period varies or is not precisely known, you can also activate the
smoothing function.
With smoothing activated, the selected sampling window has to be 5 to 9 times larger
than the modulation period so that the fluctuations caused by modulation are suffi-
ciently reduced. The sampling values are subjected to weighting (raised-von-Hann win-
dow), which corresponds to video filtering.
If you deactivate the smoothing filter, 300 to 3000 periods are required to obtain the
same effect. The sampling values are considered equivalent and are averaged in a
sampling window, which yields an integrating behavior of the measuring instrument. To
obtain optimum suppression of variations in the result, exactly adapt the modulation
period to the size of the sampling window. Otherwise, the modulation can have a con-
siderable influence, even if the sampling window is much larger than the modulation
period.
Calculating the measurement time
Normally, the measurement time is calculated as follows:
MT = 2 * AC * APER + (2 * AC - 1) * 100
μ
s
with:
MT: overall measurement time
AC: average count
APER: aperture time
100
μ
s is the time for switching the chopper phase.
Accelerating measurements
Using
[SENSe<Sensor>:][POWer:][AVG:]FAST
ON
, you can accelerate the mea-
surement as follows:
●
Chopper is disabled.
●
Average count is set to 1, no matter which average count you have set.
Thus, the overall measurement time is only defined by the aperture time, and the mea-
surement time for a fast measurement is calculated as follows:
MT = APER
The fast measurement setting delivers up to 100
000
measurements per second with-
out any blind time over randomly long time periods. Programming examples are given
in
Chapter 9.2, "Performing the fastest measurement in continuous average mode"
Remote commands:
Configuring the measurement modes
