R&S NRP
Data acquisition and parameters (Sensor menu)
1144.1400.12 4.9
E-2
N = 1, 2, 3, …
This means that the minimum theoretical measurement time can only
be obtained with smoothing turned off.
The more modulation periods fit into a sampling window, the less criti-
cal it is whether N is an integer or not. With smoothing on, about five
periods are enough to reduce fluctuations caused by modulation to an
acceptable level – even if N is not an integer. With more than nine pe-
riods, the fluctuations are imperceptible. With smoothing off, the situa-
tion is much less favourable as instead of just five periods as many as
300 are required; the fluctuations only completely disappear with more
than 3000 periods.
However, it is not advisable to make the sampling window too wide by
selecting an excessively large N, as the intrinsic noise of the sensor
increases. To reduce display fluctuations due to noise, it is best to use
the averaging filter. (
Filter / averaging, page 4.19)
For more information, see
Background information, page 4.10.
Remote Control
[SENSe[1..4]][:POWer][:AVG]:APERture[?] <float_value>
Sampling Rate
–
( )
ä
If a sensor contains a sampling A/D converter, the sampling rate can
be adjusted to prevent aliasing effects for particular types of modula-
tion signal. Aliasing can occur with some sensors because the sam-
pling frequency is located within the video bandwidth, which means
that spectral components of the modulation signal can fall in this fre-
quency range. Changing the sampling rate will make the aliasing ef-
fects disappear.
Remote Control
[SENSe[1..4]]:SAMPling[?] FREQ1 | FREQ2
Duty Cycle
–
( )
ä
ä
Using the duty cycle correction, the average power of RF bursts can be
calculated from the average power of the whole signal. The average
power of the whole signal is divided by the duty cycle of the signal.
If thermal sensors are used, this is the only way of determining burst
power.
If diode sensors from the R&S NRP-Z1x and R&S NRP-Z2x series are
used, this method must be employed if the bursts are so short that their
power cannot be measured in the
Burst Av
or
Timeslot
modes.
Remote Control
[SENSe[1..4]]:CORRection:DCYCle:STATe[?] ON | OFF
[SENSe[1..4]]:CORRection:DCYCle[:INPut][:MAGNitude][?]
<float_value>
Smoothing of
–
( )
modulated Signals
ä
ä
To reduce result fluctuations caused by modulation, this parameter
should always be activated if the size of the sampling window cannot
be exactly adjusted to the modulation period or if this is not required. If
the size of the sampling window is 5 to 9 times greater than a modula-
tion period, in general, the reduction in display fluctuation will be suffi-
cient. With smoothing off, 300 to 3000 periods are required to obtain
the same effect (
Sampling Window).
Remote Control
[SENSe[1..4]][:POWer][:AVG]:SMOothing:STATe[?] ON | OFF
