Spectrum Analyzer Mode
R&S
®
Cable Rider ZPH
177
User Manual 1321.0950.02 ─ 07
1. Press the [MEAS] key.
2. Select the "Burst Length" softkey.
The R&S Cable Rider ZPH opens an input field to define the burst length.
3. Enter the length of the burst you need.
The R&S Cable Rider ZPH performs the measurement over the time you have
entered.
If the measurement time you have entered was greater than the sweep time, the
R&S Cable Rider ZPH sets a burst length equal to the sweep time. To work with a
greater burst length, you have to increase the sweep time first.
The minimum burst length is the time corresponding to one trace pixel (= sweep
time / 711).
8.1.4.3
Setting the Reference Level
The reference level is the power level that the R&S Cable Rider ZPH expects at the RF
input. When selecting the reference level, make sure that you do not overload the R&S
Cable Rider ZPH by applying a signal whose power exceeds the maximum reference
level.
As the resolution bandwidths of the R&S Cable Rider ZPH are implemented digitally
after the A/D converter, the signal level at the A/D converter can be higher than the
level indicated by the trace, depending on the selected resolution bandwidth.
To prevent the A/D converter from being overloaded, the signal must be measured at
the widest resolution bandwidth and video bandwidth with the peak detector. The trace
maximum then determines the best reference level.
To simplify operation and to prevent incorrect measurements, the R&S Cable Rider
ZPH has an automatic routine for setting the reference level.
1. Press the [MEAS] key.
2. Select the "Level Adjust" softkey.
The R&S Cable Rider ZPH performs a measurement to determine the ideal refer-
ence level.
It uses a resolution bandwidth of 3 MHz, a video bandwidth of 3 MHz and the peak
detector. After finishing the automatic measurement, the R&S Cable Rider ZPH
sets the ideal reference level.
8.1.4.4
Using a Trigger
When measuring a burst, it is often to set a trigger before measurement is taken.
If a trigger is active, the R&S Cable Rider ZPH uses the video trigger for TDMA mea-
surements by default. The video trigger level is at 50 % of the range of the vertical axis
but is variable. This means, the R&S Cable Rider ZPH triggers a measurement if the
rising edge of the burst exceeds this 50 % line.
Performing Spectrum Measurements
